Introduction: Showerloop

Picture of Showerloop

Showerloop is a water filtration and purification system that recycles shower water in real time allowing you to shower with hot water for a long time but only use 10 liters of water per shower (normal shower = ~6-10l/min) and a fraction of the energy (around one tenth) compared to a normal shower. The device can be installed inside or outside of a shower stall or bathtub. The main components are a pump, sand and activated carbon filters and a UV-lamp. The system weighs around 20kg and is made from transparent acrylic, steel or plastic pipe connectors and copper, plastic or rubber tubing.

The total cost of the most simple version has cost me around 600€ (~$655 US) depending on availability and pricing of local materials and the components used.

The filters can last as long as two years (but more like 1 year) with daily use but depends on the behaviour and general dirtiness of the user/s. The sand filter can be washed, the activated carbon or AC can be regenerated but only at high temperatures > 500 degrees C or composted and the UV lamp should last for thousands of hours but can be recycled and replaced like any other CFL.

The basic build of Showerloop is incredibly modular in terms of placement, materials selection and aesthetics. The only constraints come from the ideal filter dimensions and the power output of the UV lamp both of which are explored in the bachelor thesis ShowerMagic : A Hygienic and Eco-Efficient Real Time Greywater Reuse System for Showers found here:

If you will build, built or are manufacturing Showerloop's or something based on this document please help us to continue working on it by donating to us, buying the KIT or parts or otherwise partnering with us. Without your support we will work our butts off to help you save the world!

Because the water should always be cleaned 100% or as close as possible the table NTU Reduction (%) above should be consulted if using different dimensions for the filter. NTU stands for Nephelometric Turbidity Units. It is a unit of measurement for the amount of particles floating in water. Drinking water has a value under 10 NTU, generally around 4 and visibly dirty water has an NTU over 15-20. NTU is measured chemically or optically. We have some design ideas for an open-source sensor, or several and would like some making them.

Although technically a 10W UV lamp can be sufficient for the removal of E.coli which is used as an indicator of water quality, other bacteria and viruses are much more potent and so we chose to use very high concentrations of UV light in order to create a safety buffer. According to our research the powerful lamp is more than sufficient in removal of bacteria even when the filters fail which means that even if the water looks, feels or tastes funny there shouldn’t be adverse health effects due to microbial action. If it does though, then it’s time to check, maintain or replace the filters. Using multiple UV lamps might be a good way to both ensure that the water is always bacteria free and all excess heat goes into maintaining water temperature.

Step 1: What You'll Need

Picture of What You'll Need


See poc21 component list above


  • laser cutting, CNC or manual routing
  • pipe working skills or handling rubber tubing
  • basic proficiency in building and assembling things
  • basic understanding of how water flows
  • patience and determination


  • one or two people
  • a working shower
  • several square meters of workspace
  • basic power tools, hand tools and the ability to use them
  • towels (there will be water everywhere in the beginning!)


MEDIUM - HIGH : Anyone with a DIY mentality can do it


  • 10+ hours finding materials
  • 1-3 hours laser cutting
  • 1-3 hours pipe bending
  • 2 hours assembling filters
  • 2 hours connecting piping
  • 2 hours for mounting
  • 2 hours for electronics assembly
  • 20 hours for everything we forgot... fixing leaks and other stuff
  • total = 22-42+ hours, with the kit 4-12 hours (and way less hassle)


  • Material costs= ~600 +- 300 Euros (~$655 US)
  • Tools if you don’t have them ~200 - 300 Euros (~$275 US)
  • general costs for material
  • costs for special services such as Laser cutter or CNC. As a reference, our Fab Lab costs for a recent build totalled around 40 Euros (~$45 US) but included components. This figure will vary, and you should contact your local Fab Lab/ maker space for their advice on this.



  • Router or laser cutter* or CNC machine, hand drill.
  • Blade saw (for cutting the filter tubes)
  • Drill (wood/plastic drill bits, circular saw bits)


  • Monkey wrench or 17, 21, 24 mm spanners
  • Pipe wrench
  • Ruler or measuring tape, straight edge, pen
  • Pipe bender (if you work with copper)
  • Hand saw (metal and wood), scissors, pliers
  • Allen driver, screwdrivers
  • Small vice

If you use copper pipe then a blowtorch and pipe bender.

Don't forget to always use safety gear: safety googles, ear protection, gloves and ventilated spaces.

OUTPUT aka Trash

Left over acrylic sheets, and ’little plastic cones’ copper pipe or random hose, paper, cut pipe and threaded rod, packaging material, tools and components you might never use again though all of them can be used to fix Showerloop - it’s always good to have tools :)

Step 2: Overview - Theory

Picture of Overview - Theory

So the main components of the filter are the pump, filter housing with the sand and activated carbon filter and the uv-lamp.

Large particles like skin cells are trapped by a layer of compressed sand. Finer particles are adsorbed by a layer of compressed activated carbon, including some chemicals like nitrates (in sweat), sulphates (in soap), chlorine and fluorine (in tap water). Finally the UV-lamp is used to sterilize the water so that bacteria can no longer reproduce. It might not seem like a big deal since our bodies are covered in bacteria but the main concern is bacteria from your bum coming into contact with your eyes.

  1. Cut filter parts
  2. Cut the filter housing pipes
  3. Cut or make gaskets
  4. Assemble flow regulators
  5. Assemble filters
  6. Assemble the UV
  7. Connect all the parts together
  8. Mount the filters
  9. Mount the UV
  10. Build a basin if needed * not in this instructable
  11. Attach pump * also not available yet.
  12. Test the system
  13. Take a shower

Step 3: Assembly Overview

Picture of Assembly Overview

I hope this isn't too confusing but there are many ways to setup the filters depending on your needs. Here are two different ways of setting it up. The first one is the most simple build (simply called 'Simple'). The only down side is that the filters quite wide with a 20mm tube with compression disks and lids also made to fit this. For this instructable I'll be going through the 'Showerloop POC21' version because it was designed and built at the POC21 innovation camp ( for more information) in France. I had an amazing experience and met awesome people that have really contributed to the project and making this Instructable possible. The photos shown, are from there. I don't mean to confuse you but just to show that there's are alternative ways connecting things together.


POC21 Build (this Instructable)

How to assemble the filter bag. Also for this there are two options, either just cutting the circle together (and either bolting it to the compression disk or just compressing it between the filtrates sand or activated carbon) or making a filter bag out of a landscaping geotextile. The benefit of using the filter bag is that changing the material is much easier, the down side is that you can't see what's going on with the filter. Personally I like to see the water flowing through the filter. Thanks to Katharina for actually making the bags and these simple and amazing instructions:

Step 4: MAKE Components

Picture of MAKE Components

Laser cut or CNC the files in the pdf Showerloop_filter_lasercuts_POC21_v3.pdf

Since laser cutters handle cutting a bit differently there may be come problems with the file. Generally red / hairlines (0.001mm) is for cutting and black is for engraving.

!If you don’t have access to a laser cutter or CNC machine, a manual router can be used to cut out the groove in the filter and the whole shape if need be. To cut a perfect circle with a router a special tool may need to be made (look for circle jig on youtube).

The lids and mounting plates can also be a single piece if you are using thick material. Four 10cm diameter x 50cm filters are required to have an appropriate flow rate of 10l/min. With 6.6l/min two filters are sufficient and 1 filter for 3.3l/min. The surface area is more important than the length of the filter because that determines the flow rate through the filter and thus reaction times. I use 10mm thick acrylic sheets for the lid and compression disks but I have used 4-5mm acrylic sheets in previous prototypes and glued them together with decent results.

A CNC machine is preferable and much, much faster.

About laser cutting: People usually only think of laser cutters being able only to etch text or a picture or to cut through a material, but playing around (carefully that is) with the settings on the laser cutter you can basically mill into a material with millimetre precision. Be warned etching deep into acrylic is probably the slowest thing you can do and making a lid can take up to two hours or more once you have figured out the ideal settings. >> Settings for Aalto FABLAB EPILOG LEGEND EXT - 60 Watts: VECTOR: POWER= 100%, SPEED= 2%, FREQUENCY= 5000 Hz, ENGRAVE= POWER=100%, SPEED=8% (etch away around 4mm), FREQUENCY= 5000 Hz ! Be careful and minimize the flame size (there shouldn’t be any).


Lids for filter

There are 2 lids per filter, the top lid and bottom lid - duh.

A hex nut is used to fasten the hose nipple (facing away from the filter) to the filter lid. The dimensions of hex nuts and/or hose nipples may vary regionally so it's best to get them first,check the measurements and modify the file if needed. In the picture of the lid only a circle was etched/milled into the acrylic lid to fit the hex nut but the design was later revised to have the shape of the hex nut itself, thereby fastening it to the lid so that it could no longer rotate (and prevent fastening) when adding the hose nipple on the outer side of the lid.

Compression disks

There are 3 compression disks per filter. Two on both ends for squeezing in the sand and activated carbon and one in between the sand and activated carbon! The compression disk in the file is nested inside the void of the mounting plate to save materials!

3 per filter. Width should be 10-15% larger than the inner width of the filter housing, in this case it's 115 mm. Lasercut (low power) or scissor cut the fabric membrane.

Lids for flow regulator

The flow regulators are just like the filters but with a single input and multiple outputs for the bottom flow regulator and vice versa for the top one.

Caps for UV lamp

The cap is on the far right. A dip is etched into it to fit the hexnut/lock nut in the same way as in the filter lid. The Male-male brass union fastened to the UV cap is what allows the water tight connection between the UV lamp and piping. Special care should be taken with this UV cap because Acrylic will still let UV light through, while not included in the following picture sets the outer side of the cap should be coated in white paint (with titanium dioxide) or otherwise taped up so that you don't get exposed to the light directly.

Step 5: Cut the Filter Housing Pipe

Cut the transparent acryclic pipe with a band saw if available or with a hand saw.

The filter housings should be 55 cm long and the flow regulator pipe should be around 10 cm long but shorter bits may work just as well and therefore require less water. The flow regulators can be left out of the build completely but there's something great about being able to see dirty water in the lower one get cleaned up by the filters and to get visual feedback in the top one which should be around eye height.

To get a straight cut the following videos are pretty helpful. The gist is to use lined up tape to get a perfect straight line around the pipe and cut around them. With a band saw you can use the leveller (aligning tool) to keep the cut straight. Because acrylic works a lot like wood you can level or adjust the cutting with sandpaper.

Step 6: Make Waterproof Gaskets

Picture of Make Waterproof Gaskets

* This step can be skipped by milling a gasket out of silicone sheets with the same depth as the 'trough' in the lid. I don’t have much advice on material selection (rubber or silicone) but there are specialist stores that could provide solid advice. I use silicone sheets. The material is best laser cut to the dimensions of the trough mentioned above. The .ai file can be found above (Gasket.pdf) Using a ‘silicone gun’ fill the circular trough with silicone up to the surface level. Use a plastic card such as a membership card you don’t mind getting a bit dirty, and with force, slide the flat surface across and over the silicone. It’s ok if it goes over or gets dirty as it can be cleaned later. Make sure that there are no bubbles or distortions in the silicone. The surface of the lid can now be cleaned toilet paper but avoid areas near the trough until it has hardened ~24 hours later. The silicone is easier to rub off once it’s dry.

Use a gasket or silicone in a similar fashion as mentioned above to connect the lower lids to the tubes. Fill the trough as mentioned in the steps above but instead of letting the material dry, press the cylinder into the lid, clamp together and then leave to dry (24 hours ideally). The silicone can be smoothed out with a gloved finger. This also reduces the surface area for bacteria or dirt to attach too. The water pressure is highest at the bottom of the filter, and so fusing the tube together with the lower lid is a good idea since it makes the seal extra strong.

So the top lids for the filters and flow regulators are the removable ones that are allowed to dry, but the lower lids can be sealed together. If you use a milled gasket the filters will hold up on their own without the need for any silicone, but assembly is easier when one side is attached. It's also possible to use acryclic glue and chemically bond the materials together, but usually costs a lot more than silicone. It should last longer than the silicone on the other hand.

Step 7: Assemble the Flow Regulators

Picture of Assemble the Flow Regulators

For the flow regulator build:

The flow regulators go together in the same way that the filters do but because they are somewhat simpler and the shape of the locknut was added I'll explain this part first.

Parts: hemp fibre, mineral oil, brass union with pipe connector (3), pipe rings (3), locknuts (3), threaded rod (14mm x4), acrylic tube (10 cm) lid 1 (10 mm), lid 2 (10 mm).

If you are using 3 filters make sure the flow regulators also have 3 outputs and 1 input for the top flow regulator and vice-versa for the bottom one. This flow regulator is only connecting to two outputs. This whole step could be replaced by a simple 3-way t-connector, but seeing the dirty water enter the bottom flow regulator and clean water enter the top one is cool.

The tube is much shorter with 10 cm length and is glued with silicone to the lid. Filter connectors on the left, pump connector on the right. As pressure is higher on the input end, if you use silicone (instead of gaskets) it's best to glue the input side.

The lids and the mounting plates would probably survive being a single piece. It's possible to heat and bend the acrylic to have a 90 degree angle and there by allow you to screw the filter into the wall and not through the wall.

Attach the locknut and the copper union together with the lid in between. The bottom flow regulator has one input (from the pump) and two outputs to the filters and the top flow regulator has two inputs (from the filters) and one output (to the UV).

This part may take some practice figuring out just how much fibre to use. You can also replace the fibre with teflon tape (pipe tape) and as a rule of thumb I do about 8 layers (times around) but it depends on the size of the hole.

hold the lock nut in place while using a spanner to tighten the union to the lock nut. a hose nipple can also be used instead of the copper union.

Then do the lid on the other side.

So the order is mounting plate, lid 1 (with lock nut and union), tube, lid 2 (with lock nut and union), mounting plate, threaded rod, nuts.


Step 8: Assemble the Filters

Picture of Assemble the Filters

Just like with the flow regulator, slot the hexnut into the groove in the lid and screw in the brass male-male union (or male thread hose connector) on the flat outer side of the lid.

ABOVE: Filter lid, teflon tape, male-male union for copper pipes and hex/lock nut.

Use hemp fibre and mineral oil or a lot of teflon tape around the union and hex or + use silicone to seal the thing for good.

Do this for both lids. Go back a step for more detailed instructions.

Place the bottom lid on a flat surface and add the 50cm pipe on top. Clamp it to the table or have someone help you.

Insert the left over acrylic 'coins' from the laser cutting into the bottom lid (maybe glue them in). It's best to have two people for this step or use a clamp to hold the filter in place while adding the filtrates.

Insert compression disk 1 with the fabric piece on the bottom so it swoops up and covers the corners of the inner lid - this makes a tight seal, or use water proof nuts and bolts like in the images above (M3 or M4).

Sand filter with compression disk, activated carbon bag in the background.

Pour in 10 cm of washed quartz sand either into the sand bag or just straight into the filter. Level it out. Insert compression disk 2 and squeeze it in to the pipe. Pour in 40 cm of activated carbon, either into the activated carbon bag or just straight into the filter. Level it out. Insert compression disk 3 with the larger fabric piece on the bottom so it swoops up and covers the corners of the inner lid. Squeeze it in. The level of the compression disk should be above the pipe at this point, if it's not, add more activated carbon.

Insert left over acrylic coins into the top lid (maybe glue them in) like you did for the bottom add the top lid add mounting disks to the top and bottom (same as with the flow regulators). Place threaded rods through all the corner holes.

Attach washers. Make sure everything is aligned together. Adjust the rods to the desired height and screw/wind in the nuts. Use the corner of a table/ worktop for tightening the bottom nuts. Compress the top and bottom lids together using a spanner or monkey wrench to tighten the nuts. You need to fasten both nuts while tightening or the rod will just keep spinning around Apply a little bit of lateral pressure on the threaded rod (squeeze it towards the filter housing) while tightening. If you did it correctly, the lid should now be water tight with hex nuts on the inside of the filter, the filtrate inside and the connector bits / hose connectors on the outside. If the filter housing leaks when pumping water through the filter; the nuts need to be tightened more. If it still leaks check the alignment of the lids and the gaskets. Don't tighten it too much or you'll likely crack the lid.

Step 9: Connecting the Piping? -> Mounting the Filters to the Wall.

Picture of Connecting the Piping? -> Mounting the Filters to the Wall.

*This part varies a lot depending on your build*
I accidentally broke the back panel of the shower stall and quickly built a new one with plywood that was routered to fit the frame of the shower stall. This mishap allowed for access to the back which is not very common and so modifications will be required for this step.

Bend copper pipes or just connect the hose
Basics - heat up your copper pipe with a blowtorch. Focus the flame on the areas above and below where you will do the bending so that part doesn’t get hotter and thus weaker than the rest of the steel. Once the copper turns blackish and starts making a cool psychedelic rainbow effect you know the copper is warm enough to begin bending. Turn off the flame and wait a moment. Once the pipe has cooled a little use the pipe bending tool so make an appropriate bend. This is more craft than technical skill and you just have to observe and see how the metal flexes. Don’t put too much pressure on one spot, this may result in a distorted pipe. You want to keep the diameter of the inner pipe as even as possible. Use a pipe bending tool.

+ hose connector Using rubber hose [or PEX] it is much easier than copper but perhaps it won’t look as cool. Transparent tube isn’t too bad but the most common material is PVC (which is kind of nasty). The best and perhaps easiest option is to use drinking water hose (16mm?). The hose connection is simple, use a hose nipple instead of the threaded connector and fasten the hose with a ring clamp. Make sure it’s really right. For really easy access you can you quick release/ quick connectors that allow you to connect and disconnect individual components without twisting the tubes around. These are usually used with garden hoses and are available as plastic or metal pieces. There's a diagram of how to do this with hose earlier on.

Lay out all the filter components onto a surface. Using common sense and a ruler you can centre everything perfectly.

Once you're happy with the positions bend the pipe accordingly.

To help cut the pipe you can use a pipe cutting tool but the cheap ones get dull really quickly.

Finally ready to test the filters by attaching a shower hose to the input and output of the flow regulators.

There's a short stop motion I'm having trouble embedding linked here:

The placement of the filters was drawn onto a waterproof material and holes cut where the mount plates go through.

The mount plates can be bent by 90 degrees which would allow for the filters to be hung directly into the wall. To bend acrylic you need a special device that's basically a heated up wire that weakend specifically the bend point. Once it's warm enough you can just bend it by hand and into the shape you want (it's good to have a template that you can push up against). Let it cool and it will harden into shape. It may be prudent to space the holes in such a way that they screw in between tiles as drilling into tiles without cracking them can be tricky. If you have a basic cement wall you are good to go. Alternatively the threaded rod can be extended all the way from the ground to the roof and fastened with tension (pushing up and down) or simple legs or L-bends can be made so that they can be screwed into the roof and or floor. Or just attach the metal rods used to compress the filter directly to the wall.

Step 10: Make the Backplate

Picture of Make the Backplate

To fit inside the existing frame I had to bevel my 20mm plywood to half way. By clamping a straight piece of material onto the edge I could simply push against it with the router while moving laterally to get a clean and straight cut.

Lay out the cut lines on top of the plywood (and clamp/tap it down)

Use a circle saw to cut the holes for the hot/cold water mixer.

Missing from the step is how the water proof membrane was attached to the 'wet' wall. Ideally some kind of glue would make the most sense.

Insert the mount plates through the wall and using bolts or cut threaded rod, washers and nuts fasten the mount plate/filter or regulator to the wall. The holes where a bit too far out for the mount plates so there was too big of a gap to just use nuts to hold everything tightly together, so some 20mm plywood was cut and holes attached (in the same positions as the mount plates) to get a tight fit between the mount plate, plywood and wall.

Here's a picture of Timm and the back wall in it's entirety. The black semi-circles are something that came with the UV-lamp which let's us mount it easily. Normally this would be on the inside of the shower but this version was so big it couldn't fit inside the shower horizontally. While smaller UV lamps of 20W should be sufficient for 10l/min the numbers seem to vary from supplier to supplier and I would lean on the side of caution. A cool set up could be to have a small UV pre filter and after the filter whereby the pre filter UV may be good enough to reduce or stop bacterial growth inside the filter all together which does occur even in drinking water filters, but the type of bacteria isn't harmful. In either case this is what the post-filter UV is for, to make sure that there are no negative effects.

Step 11: Assemble the UV

Picture of Assemble the UV

The UV lamp comes with it's own 'ice-cream' cone shaped hose connectors, but generally they are for 1" or larger hoses and it extends out too far to look cool so it's nicer to make a custom cap which reduces the form factor.

You should have laser cut the cap from the previous step. It can be seen in the picture on the right, next to the lock nut and brass union.

! the cap should actually be made from something that's UVC resistant as Acrylic will allow for the transmission of harmful UV rays. PTFE is one option and the same material that the teflon tape is made from as is PVC (but you shouldn't vaporize it/laser cut it because it's harmful to your health to breathe and so don't let it into the environment either). A very simple solution would just be to coat it in several layers of white paint containing titanium dioxide which is basically where the pigment comes from. Do this for both the inner and out layer to ensure good protection. Machining this component into rustproof steel like alumnium or die casting may be the best solution in the long run. Remember the UVC is on a non visible spectrum so be practical whenever dealing with UV light.

More information and links on the bottom of the page.

Place the lock nut inside the UV cap. Use teflon tape or hemp fibre with some mineral oil and place it inside the UV cap.

Place the brass union inside while holding in the lock nut. Use a spanner and possibly clamp to fasten the union to the locknut.

Place the UV cap inside the threaded hose connector lid and add the gasket to the inner side that comes into contact with the UV lamp.

Tighten and you're good to go. Add a desired hose connector to the threaded union to connect the UV to the shower head.

Exerpt from:

UV energy absorbed by plastics can excite photons, which then create free radicals. While many pure plastics cannot absorb UV radiation, the presence of catalyst residues and other impurities will often act as receptors, causing degradation. Only a very small amount of impurity may be needed for the degradation to occur, e.g. trace parts per billion values of sodium in polycarbonate will initiate color instability. In the presence of oxygen the free radicals form oxygen hydroperoxides that can break the double bonds of the backbone chain leading to a brittle structure. This process is often called photo-oxidation. However, in the absence of oxygen there will still be degradation due to the cross-linking process which is the effect for plastics used for the Hubble Space Telescope and International Space Station.

Unmodified types of plastics that are regarded as having unacceptable resistance to UV are POM (Acetal), PC, ABS and PA6/6. Other plastics such as PET, PP, HDPE, PA12, PA11, PA6, PES, PPO, PBT and PPO are regarded as fair. Note that a PC/ABS alloy is also graded as fair. Good resistance to ultraviolet rays can be achieved from polymers extruded by Zeus such as PTFE, PVDF, FEP, and PEEKTM. The only plastics found with excellent resistance are the imides, Polyimide (PI) as used in the Hubble Space Telescope and Polyetherimide (PEI).

PTFE has particularly good UV resistance because of its very strong carbon-fluorine (C-F) bond [almost 30% higher than the carbon-hydrogen (C-H) bond], which is the common side bond that surrounds the carbon (C-C) backbone in a helix and protects it. Most fluoropolymers also do not have the light absorbing chromophore impurities in their structure that can act as an initiator for photo-oxidation.

One useful interaction of UV and plastics is with fluorescent whitening agents (FWA). In natural light many polymer products can appear to have a yellow appearance. But by adding a FWA the UV light absorbed is then emitted in the blue region of visible light (400-500nm wavelength), instead of the yellow region. Compared to other additives FWAs only need to be added at small levels, typically 0.01 — 0.05 % by weight.

How to Avoid UV Degradation

There are several ways of avoiding UV degradation in plastics — by using stabilizers, absorbers or blockers. For many outdoor applications, the simple addition of carbon black at around a 2% level will provide the protection for the structure by the blocking process. Other pigments such as titanium dioxide can also be effective. Organic compounds such as benzophenones and benzotriazoles are typical absorbers which selectively absorb the UV and re-emit at a less harmful wavelength, mainly as heat. The benzotriazole type is good, as it has a low color and can be used at low dose rates below 0.5%.

The other main mechanism for protection is to add a stabilizer, the most common being a HALS (Hindered Amine Light Stabilizer). These absorb the excited groups and prevent the chemical reaction of the radicals.

Step 12: Start Using It.

So this is the part where I run out of photos. You still need to attach the drain and the pump together. This part will vary depending on the drain. There are three ways to do this: 1) take over the drain pipe with some connectors and attach something similar to the UV cap to connect a large PVC pipe to a thinner hose.

Attach the drain hose to the pump with female hose connectors. Some pumps come with different types of connectors - with threads or without and sometimes you don't always get what you ordered so you have to spend some time in the plumbing section of the hardware store for this. Ring clamps are your friends.

Now this part is super essential and obvious component if you want to build Showerloop. It needs to have a 3-way valve by the drain which allows you to either pump the water through the filters or let the water go down the drain - or water storage tank/toilet/etc. So if you can fit it in you can add the three - way valve. Alternatively I made a special basin with two drain plugs whereby one goes into the Showerloop filter and the other one goes into the drain drain. I'm also working on a 2-in-1 solution, which I hope to release in the next Instructable.

Reheating the water: Just use tap water for now, we will add a tutorial on how to use an electrical resistor to heat up the water.

Wire the electricals safely out of the way: This is super important and for sure something that you've already thought about. Basically the pump and UV that I use are all rated to be water proof / water resistant. It's a good idea to house everything in a water proof container. I'm still working on this part and the ones mentioned above and will release a new Instructable showing how I combined it with an existing shower in the coming weeks/months.

Test the shower:

This part is simple. Just turn it on and see if it leaks. This is common for me in the beginning, usually something is just a bit too loose and some monkey wrench action will fix it all up.

Try out the shower:

The first time using it I would maybe have someone on standby to make sure everything is ok. Have it running on it's own for an 10 minutes without 'recycling' to clear the activated carbon and sand of dust (which will happen when you compress it the first time). Then have the system to run on it's own for up to an hour in recycling mode just to watch it do it's thing. After this it should be good enough to try on it's own.

Coming next:

solenoid valves, some drain hacks, using a different kind of pump, and adding buttons and and more control.

I'm hoping to make a living out of developing, building and helping others build Showerloop to fit to their own needs. If you want to support me you can join the R&D group we are setting up, donate to my cause or even buy our Showerloop KIT, more info at Also more relevant info is posted on our facebook page .

We are solving some of the bits and pieces mentioned above, but many of them have already been solved. This Instructable is a bit behind on the developments that I've made since POC21 which is why I'll be making a new update very soon. The filters, pump, UV and connections are all the same in our KIT, it simply incorporates some of the solutions mentioned above so I wouldn't discourage anyone from following this Instructable if they feel able to solve the last steps on their own. I'd be really happy to see what you come up with and so far I'm able to answer any questions that people have.


GrantC4 (author)2017-05-29

What would I need to add to this system to be able to run sink water through it without ruining the filter? Have you tested anything like this?

(i.e. the oilly, food filled water from washing dishes).

GrantC4 (author)2017-04-22

I will be making an off the grid house and was wondering if after the water goes through the filter I can add it back to my drinking water container? (After I finish showering add the water back into the main container)
Or should I have a separate container dedicated for the shower. Also, if I have a washing machine, would this be able to clean the used water to drinking standards?

Showerloop (author)GrantC42017-04-24

Hey, while it met drinking water standards in our tests I wouldn't recommend closing the loop just yet, at least until doing some decent amount of testing. Storing and observing, tasting and smelling can be enough. Same goes with the washing machine stuff. We really need to work on testing more soaps and detergents but I don't have any funding so a lot of that work is behind.
My recommendation for the start would be to store the used water in a secondary tank and use it as you would grey water just to be on the safe side. I think that you could easily go from the shower to the washing machine though.
Hope this helped.

GrantC4 (author)Showerloop2017-04-24

Ok, what if I only used biodegradable soaps? (all organic, no bad stuff, etc)
Do you think it would be fine then?

Or how about having a separate tank used only for the washer and shower (or a small one for each).

Also, which soaps have you tested? are there any that make it through the filter?


neyhart (author)2017-03-27

Brilliant concept! Where can I purchase a kit you spoke of earlier? Very interested.

Cagri Kanver (author)2017-03-19

Pretty smart one!

JetForMe (author)2016-04-02

I'm excited to make a semi-portable shower, complete with solar water heating, for daily showers at Burning Man next year.

pminer (author)JetForMe2017-03-18

Did you end up doing this for BM? My wife doesn't want to go again unless she can shower this year...

JetForMe (author)pminer2017-03-18

No, haven't been back yet. Maybe next year, although I'm not sure I'll do the shower.

Showerloop (author)JetForMe2016-04-04


Showerloop (author)Showerloop2016-04-04

If you get me tickets there I'll help you build it ;)

f1dd13r (author)2017-01-15

Clever. I do the poor person's version of this. I have a portable pump shower with a filter built in which I use with a bucket of hot water then have the shower curtain draped so almost all the water is directed back into the bucket.

LandonSalvador (author)2016-09-27


Luis Doporto (author)2016-08-19


jessyjackson (author)2016-07-06


ezrasmith21 (author)2016-06-23


cesle (author)2016-05-15

Bonjour, please forgive my bad english :)

This idea is amazing, I want to install it in my home, two adults and two kids, we use daily too many water ... I don't have enought skills and tools to build it by myself ... the kit should be perfect... but I have many questions about how to install it in the actual shower... and it's very expensive for us, so I can't risk a failled system... (because of my lack of skills)

... A half way system couldn't be developped? A simple heating loop not filtered and use an extra rinse water? I wonder about the recovery of the water out of the plumbing configuration to direct water to the loop or the evacuation. I haven't found this information / scheme. If I were to get critical is to make explanations accessible to people with very little or no skills at all ... only way to share this great idea to many people as possible ... I want to evolve, but I need much more informations and help than what you already give ^^D

By the way, a uge thank to the work already done and please keep going :)

Guliavan (author)2016-03-02

This is an awesome project. Thanks for sharing ! I'd like to try it out. I'm in an isolated house with a water well not connected to sewers and the septic installations are getting old. I'm not sure if there's space left for new ones. I might end up with a sealed tank which is very costly to empty.

I was thinking if that system to be extended to another context, such as a washing machine for instance. So that I could do several washes using the same water.

Would it be the same kind of system but larger ?

TheAtomicSoul (author)Guliavan2016-03-09

You would need a very large holding tank. Since most machines only run two wash cycles per wash (one with soap, one to rinse), double the amount of water your washing machine is designed to hold, then add about 1/4 of that as extra.

Almost all laundry soap you buy now is HE (High Efficiency) and shouldn't be any more issue than whats used in a bath.

Guliavan (author)TheAtomicSoul2016-03-10

Great, thanks for the insight ! Much appreciated !

Showerloop (author)Guliavan2016-03-03

Yes I think it could work. Since there is some period between washes (?) you may not need to scale up the system but just run the water through several times. Haven't studied that type of dirt and detergent load but I'm sure with some modification you could make it work.
A storage and settling tank for instance would capture and separate some material and a way to skim off floating oil/grease would also help.

Guliavan (author)Showerloop2016-03-03

Nice, thanks for the reply and again, very nice project !

DotDoStuff (author)2016-02-02

Quote: "Without your support we will work our butts off to help you save the world!"
I'm not sure that's what they mean, but hey - nice project.

Wonder how much one would save when all is added up.

Showerloop (author)DotDoStuff2016-02-10

Hahaha, oh no. I meant it the other way around as I was hoping to setup a donation kind of thing but I just don't know how to ask for help :/

Turkeyboy111 (author)Showerloop2016-03-01

You should make a Kickstarter or a similar crowdfunding campaign in order to expedite the research of this amazing device. It would seem that you have ample supporters.

Peter-GeertB (author)2016-02-16

A very interesting project. I have one question: Does the water get very cold after showering for a while, because I do not see any heating or adding hot water. Is that correct?

Showerloop (author)Peter-GeertB2016-02-18

Yes you're right. I'm trying to find ways of avoiding electrical heating - so using solar thermal or using a heat exchanger to extract waste heat from another process. The benefit is of course that a really small and inexpensive system is enough.

The simplest thing to do is to add a some more warm water from the tap every now and then which does reduce efficiency, but it's still better than the 1:1 we have now.

Though not for everybody, you can also just start with hot water and let it cool down over time and leave once it get's uncomfortable. If the shower stall is well insulated this can be at least 5 minutes.

DavidS531 (author)2016-01-24

Always use PEX and/or Shark Bight (or is it Bite?) over copper or PVC. Cost far less, easier to use, faster to install, works very well with existing copper, plastic or galvanized and won't burst in freezing situations nearly as easily. Overall, this is a great money saving, long run DIY. I didn't do this, but I did make one that with the push of a button, your lightly filtered water (using GREEN/ Organic soaps) could be rerouted to your yard and/or garden that worked nicely.

Showerloop (author)DavidS5312016-01-24

I'd want to try PEX but you need all those special tools to get started with it. Do you know of any affordable options?

DavidS531 (author)Showerloop2016-01-27

Negative, there are only two "special" tools and they are just to make things go much easier, not needed but really a big help. They are the pipe cutter, which is just a large, very sharp bladed scissor like item and the release tool which looks like a plastic "C" for the times we might need to make changes (commonly called mistakes), in the length, adaptors and/or routing of the pipe. Nothing too "special" but nice (and cheap) to have. No glue, cleaners, no fuss, no muss. There are release tools for each size of pipe, as I remember about $1 ea. and to make things look really sharp they have nail type clamps to mount everything. There are 90 degree adaptors, length connectors, changing size adaptors, adaptors for attaching to galvanized or faucets, basically everything you need to plum any home or business in a third of the time. The pipe will freeze but the difference is that it expanse without bursting then when it thaws, it's all good to go, no problems. And with the quick connector, you can hook up to any copper or plastic with NO glue or welding. THIS STUFF IS GREAT.

Showerloop (author)DavidS5312016-02-10

Thanks for the information. It looks like the easiest option. Do you know about the environmental impacts of it compared to copper? Because you can recycle metal. Plastics not so much. The overall footprint might be smaller for lightweight stuff when you count production and transportation. Mass = fuel.

DavidS531 (author)Showerloop2016-02-12

Pex is very versitile. I have had customers change their mind and had to pull it a part, very easily, and reused it in other areas. I am sure the shelf life is forever or more, but like I said it can be reused in many other prodjects, then reused again, if need be, or left alone for the duration. Which means little to no environmental impact when used properly.

You don't need special tools anymore. The SharkBite couplers are amazing. They are push on connectors that can connect to copper or pex or connect the two. I used them when I had to replace a hot water heater located in a crawl space. They were a godsend. All you need is a cutter to make nice clean ends.

I'll see if I can get them to Finland.

mist42nz (author)2016-01-30

that is not a flow regulator.

Showerloop (author)mist42nz2016-01-31

I think you're right. We just had to come up with a name and it stuck. What would you call it.

mist42nz (author)Showerloop2016-01-31

A flow regulator...well google it. it limits the volume of liquid and pressure, usually by a mesh or frame with holes in fact your compression disks are pretty much flow regulators.

I would consider it an inspection junction, or inspection point.
Junction because that's effectively what it does, it allows extra water flow by adding more and more parallel branches, while keeping an easy to find, narrower (and stronger) pipes and tubes.

Showerloop (author)mist42nz2016-02-10

Ok that sounds reasonable. Will add it.

dbuckley6 (author)2016-01-25

Activated carbon can adsorb and neutralise gases. However it does not have this function when wet. It will still have a filtering property, but no more than sand of the same particle size.
Nice project though, very well described.
I have always wondered why a simple heat exchanger is not available to fit under the shower floor to take the heat from the exited water to warm up the cold water used in the mix. Anybody ever tried to make one or seen a product like this?

SeimonW (author)dbuckley62016-02-05

Yes, there are a few out there - for example (no affiliation)

mist42nz (author)2016-01-30

the carbon wont do anything wet.
for the material filter, what micro size are you going down to? would dairy "sock" filters be a more convenient way to get them?
have you considered zeolite for a primary particle filter, it backflushes better than sand.
What temperature does the water re-feed at? I've got full solar water, but would love a way to move up to a 300mm shower head (or multihead shower)...without the excess wastage. (hoping also to move to prodominantly rain fed water supply)

Showerloop (author)mist42nz2016-02-01

Carbon does work when wet and is commonly used in waste water treatment plants and even aquarium filters.

Zeolite seemed too expensive for me but Finland is a small place with not much on the shelves so it may be more affordable in other places. I totally encourage people to try things out. If we could codevelop this around the world we will have showers that use practically no water but feel like a water fall.

Water re-feed rate depends on the conditions of your bathroom as the heat is dissipating into the air, wall and floor.

mist42nz (author)2016-01-30

you're going to need a good UV filter to deal with the bacteria, fungus, and algae you're growing in your human cell medium with it's plentiful light supply. (water + light = algae, unless water is very sterile.

francesca.braun (author)2016-01-27

why not make a kit and try to raise money on headstart ?

We're making a few KITs now until we get things ready :)

please let me know when it will be ready. i would like to buy it.

ac0kg (author)2016-01-28

Nice build, and interesting papers.

Have you or do you plan to profile the actual contaminant load produced by a person in the shower? (Seems like the kind of experiment that might lead to some fun stories.)

I'm curious about contaminant concentration vs time, it would be interesting to see analysis of water samples taken once per minute from the operating shower over a 10 minute run, both with and without a person in the shower.

Have you measured filter performance over time to verify that performance remains acceptable after a couple of hundred simulated showers?

What's the embodied energy of the components used in construction, and how long do you anticipate that it will take to reach energy break-even for your market area? Large scale water treatment is likely fairly energy efficient per unit volume of treated water relative to small-scale treatment, so I'm curious how quickly the water and water treatment savings become positive.

Showerloop made it! (author)ac0kg2016-01-28

Hey, great questions.

I would love to profile contaminant loads but I don't currently have access to a lab. All our test water experiments were based on the highest detected values for shower water based on the literature we could find. While not detailed in this instructable (coming next time), we've added t-connectors and valves to allow a user to backwash and bypass the filters, this way larger debris can be washed out and pre-washing can be made possible. So if you fell in a pile of mud, you could rinse off without activating the filters. This has made it a bit tricky to define just how long the filters actually last for because it's user specific and we're just starting to collect user data in parallel to lab experiments. The UV handled bacteria very well even without filtration which was surprising but also encouraging.

We had some MIPS (material input per service unit) calculations done by an outside party but this was early on in our research and so many of the calculations were based on estimates. We'll hopefully have that for the next instructable as well. The gist was that with a 20 year service life the abiotic input/output 'improvement' was by 1/3 and air emissions almost 1/5th and water was a bit off the charts.

Large scale water treatment is effective but with Showerloop one can also save energy. This is a good reminder to fix the calculator that we had on our website so you could calculate the potential savings for your own habits, but I'm bad at Javascript so I couldn't get it working. Will add that in the soon-time. For average use cases the ROI is supposed to be around 6 years for a single person in Finland (water at 1.5e/m3 and electricity under 80e/MWh).

aaarrrgggh (author)2016-01-27

Really cool idea. Is there any risk to bacteria (legionella or mold) growing in the filter? Would there be another way to neutralize the sulphates other than the activated carbon?

JamesA133 (author)2016-01-26

Im in the process of building a home in a bus to remove myself from the grid. This shower idea could work well for me. Im not sure how i can help support you as im aleady going to need to change up the materials needed to make it cost possible for myself. Ill try keep in contact on how/if this goes. Thank you for the inspiration.

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