How to Make a Laundry Water Recycler (Gray Water System)




Introduction: How to Make a Laundry Water Recycler (Gray Water System)

About: By day I'm a mechanical engineer at a university laboratory. In my free time, I do my own projects.

For those interested in getting into gray water, this may be one of the easiest ways. I got this idea from Home Use of Graywater from the University of Arizona. The idea is very simple: Save the rinse water from one load of laundry in a tank and use that water to wash the next load, cutting the amount of water you use for laundry by 50%. By the way, this idea has been patented, but I don't think any commercial products using it have been made (a commenter corrected me on this).

I built my Laundry Water Recycler (LWR) over a year ago for a cost of about $60, and since then my household has saved four or five thousands gallons of water. You might be concerned that washing with the rinse water could discolor your clothes, but we have not encountered that problem.

This device is intended to work with older top-loading washing machines, where it saves about 20 gallons per load on average. Newer front loaders already use much less water, and, according to this article, they don't have a distinct rinse cycle anyway. Clearly, front-loading washing machines use less water than even a top-loader with the LWR, and the use less energy too. However, in comparing the two, you also need to factor in the energy it takes to manufacture a new washing machine. If you keep your top-loader for a while, then that manufacturing energy is not consumed yet. Anyway, enough green theory, onto the LWR!

The image below shows the LWR. At the bottom of the image is the top of our washing machine. Just above the left side of the machine is the washer outlet hose, which splits into two branches, each with its own ball valve. In this photo, the left ball valve is open, so the water leaving the washing machine will be pumped into the drain pipe at the top of the photo. The valve on the right leads to the storage tank, a 32 gallon plastic trash can, which is suspended from the ceiling on a hanging platform. An outlet at the bottom of the tank has a hose connected to it and this is used to introduce water into the washing machine at the beginning of a washing cycle.

Step 1: Is This Project for You?

In order to build the LWR you need to have room directly (or nearly) above your washing machine for the tank. You also need a way to secure the tank safely, because when full it will weigh more than 250 pounds. My washing machine is in the basement, so it was easy to hang a platform from hooks screwed into the ceiling joists. If you are setting this up inside your house, then you must be able to fasten the tank platform to something that can bear the weight, such as your ceiling joists. It will be more tricky, because the joists won't be visible. Make sure you know what you are doing in regards to this issue, or get help. Alternatively, you could build a platform from the floor up, but that would take up more space, cost more, and take more time to build.

Step 2: Materials List and Tools

Note: The sizes of the pipes and fittings that are stated here are what I used. You may end up with different sizes depending on what you find at your hardware store. As long as you are able to connect everything together and not have any leaks, you are fine.

Tank and Plumbing
  • 1 32 Gallon Plastic Trash Can
  • 2 3/4" PVC Ball Valves
  • 5 1-1/2" hose clamps
  • 1" ID washing machine hose (length will vary depending on your setup)
  • 1 washing machine hose hook end
  • 32" of 11/4" corrugated sump pump hose
  • 3/4" diameter PVC pipe (around 3 ft. of length)
  • 1 3/4" diameter PVC 45 degree turn (or a "T")
  • 2 PVC threaded adapter - 1" male thread to 1-1/4"female thread
  • 2 PVC adapter, 1" male thread to 1-1/4" diameter
  • 1 Threaded hook with a nut (for holding up the end of the tank outlet hose)

Hanging Platform
  • 4 lengths chain (rated 80-100 lb), length depends on your particular hanging situations
  • 1 length of the same chain 24" long
  • 4 wood screw threaded hooks (rated 80-100 lb)
*4 machine screw hooks with nuts (rated 80-100 lb)
  • 4 1-1/4" ID rubber washers (or make your own from used bicycle inner tubes)
  • 2 1-1/2" metal pipe thread nuts
  • 1 12" x 20-3/4" plywood, reinforced with metal, at least at the corners

Water level sign
  • Top from a qt. yogurt container
  • popsicle stick
  • 1 machine screw
  • small piece of velcro (both male and female)

Load Size Measuring Tool
  • 1 piece of PVC pipe, 3/4" or 1", cut wide enough to sit in the top of your washer basin
  • 1 threaded rod (#6 or #8 thread)
  • 1 lock nut for each of the load sizes your washer has (mine has 4)
  • 2 nuts and 2 washers to fasten the threaded rod to the pipe

Ball Valve Wrench
  • 1 piece of 2" diam ABS pipe 8-10" long

  • Electric Drill
  • 1-5/8" hole saw
  • Dremel Tool
  • Utility Knife
  • Hack Saw
  • Teflon Tape
  • 2 pipe wrenches
  • PC-7 Multipurpose Waterproof Epoxy
  • PVC Cement
  • Twist Ties

Step 3: Setting Up the Tank

The tank will have two outlets, one at the bottom that is normally used, and one at the top for a safety overflow. You will notice from the intro photo that my LWR doesn't have a safety overflow. This is because I haven't gotten around to adding it yet. Yes, my tank has overflowed a few times, and it wasn't too fun. However, my washing machine is in the basement, so when my tank overflows it doesn't cause much of a problem. Unless you are willing to have gallons of slightly soapy water gushing onto your floor, do yourself a favor and put in the safety overflow outlet from the beginning.

To make a tank outlet, cut a 1-5/8" hole in the tank wall with the hole saw (or very carefully cut a circle of that diameter with a utility knife). Cut the bottom outlet hole near the bottom of the tank, but high enough to allow all of the hardware to fit (especially the metal nut on the inside). For the safety outlet, cut another 1 5/8" hole in the top of the tank wall, again, leaving space for the hardware at the top.

Slide one of the rubber washers over the male end of the PVC threaded adapter. Insert that end through the hole from the tank exterior. Slide another rubber washer over the male end and then screw on a metal 1-1/2" thread washer over it. From outside to inside you should now have the following order of parts: The outer lip of the adapter, washer, tank wall, washer, metal nut. The two accompanying photos show views of the outside and inside of an outlet. The inside view shows a store-bought rubber washer and the outside view shows a washer made from a piece of tire inner tube.

Next, tighten the metal nut as much as you can by hand, and then use to two pipe wrenches to finish tightening it up. This step is easier with two people. One holds the outside of the adapter fixed with one pipe wrench, while the other person tightens the nut inside the tank. It is possible to tighten the nut too much, and deform or tear the washer.

Next attach, the outlet hose. Here, a secondPVC adapter is threaded into the outlet female thread, with teflon tape between the threads. Finally, slide the connecting end of a length of 1-1/4" corrugated hose over the adapter and tighten with a hose clamp (3rd photo below).

When not in use, the hose should be fastened so its end is at or above the top of the tank, otherwise water will leak out. The 4th photo below shows how I did this. I have a threaded hook passing through the tank wall and tightened with a nut. The hose has a piece of flexible wire wrapped around it and hanging from the hook (twist tie material will work as well).

Do a leak check by filling the tank with a few inches of water. If water leaks anywhere, some trial and error with tightening or loosening the metal nut should fix the problem. Being leak proof is much more important for the bottom outlet, because that one will be used all of the time and will also be under pressure. The top outlet will probably work OK even if it is not a perfect seal.

Step 4: Making a Hanging Platform

My hanging platform is a piece of 3/4" plywood reinforced with two aluminum bars. There are many other ways to do this, just make sure that the platform can handle a weight of 250 lbs. The platform has a threaded hook in each corner that passes through the aluminum bar and is fastened with a nut.

When you purchase the two types of hooks and the chain, check that they are rated to more than a quarter of 250 pounds. In my case, all of these items were rated between 80 and a 100 pounds, so my hardware has a margin of safety of about 70 pounds above the maximum weight of the tank.

Next, after drilling a small pilot hole, screw the wood screw hooks into the ceiling joists (third photo below), if possible placed symmetrically over the area where you want the platform to hang.

Hook the chain over the upper hooks and then onto the lower hooks of the platform. Adjust the hooking of the bottom links until the platform is nearly level. Then, place the water tank on the platform and do a final set of adjustments on the chain links.

My platform hasn't given me any trouble during the last year. The wall behind it in my basement is concrete, but if you have a more delicate wall in that location, you may want to put some padding on the back edge of the shelf. Another safety feature that I should add, but haven't, is to bolt the back of the shelf to the wall itself, loosely, so that, in the event of an earthquake, the shelf would not be able to swing too much.

Step 5: Setting Up the Plumbing

As you can see in the intro photo, my washing machine has an unusual drain set up, with the drain pipe opening being several feet above the washer. This is because the machine is in the basement and the extra height is required to have the water drain into our sewer pipe. I think in most homes the outlet hose enters the drain pipe at a level close to the top of the washing machine, or perhaps nearer to the floor.

In any case, you will be adding a set of diverting valves that will allow the flow of water to either go to the drain, or up to the storage tank. The photo below shows my setup. The heart of the plumbing is a "Y" pipe. I made this "Y" myself from a 45 degree PVC fitting because I was not able to find one in any store. If you know of any place to buy a PVC "Y" in this size range (3/4" to 1-1/4"), please let me know. I made the "Y" by cutting a hole in the side of the angle fitting that was in line with the opposite opening. I started the hole with a drill, and shaped it carefully with a Dremel tool and a utility knife. A Dremel took is an extremely fast rotating cylinder of sandpaper that makes jobs like this easy. If you don't have access to a Dremel, I would think that this would be a pretty time consuming task. The final hole was elliptical, because it is made at an angle to the material wall.

Finally, I glued a short length of 3/4" PVC pipe into the hole with PC-7 epoxy. This epoxy is quite strong and I glopped a lot of it around the joint (the dark gray stuff in the picture below).

If you don't want to go to all the trouble of making your own "Y", a "T" fitting will work just fine. I didn't want to use a "T" because I know from my engineering studies that it takes less energy to pump water through a 45 degree angle than through a 90 degree turn. Since I am already asking a lot from the washing machine pump, I wanted to make its job a little easier. If you use a "T" you can put it "sideways" so that the path up to the storage tank is a straight shot, while the right angle goes to the lower drain. There also may be easier ways to make a "Y" - Let me know if you think of any.

In the other two openings of the "Y", I glued in short lengths of 3/4" PVC with PVC cement. At the bottom of the "Y" the outlet hose from my washer fit over the 3/4" PVC and I fastened them together with a hose clamp.

For each of the two ball valves, I also glued a piece of 3/4" PVC at each end. The bottom end of each valve opening was then glued with PVC cement to the top openings of the "Y". A better way to do this would have been to use flexible couplings between the "Y" and the valves. Being a novice at plumbing, I didn't know about this option when I built it, but that's the way I would do it now because then the connection between the "Y" and the valves would not be permanent. (However, flexible couplings may not be available for small pipes such as these anyway).

Finally, you need to fasten the outlet openings from each ball valve to an appropriate length of hose, one going to the drain and the other up to the storage tank. I used the typical rubber washing machine hose (1" ID, 1-1/4" OD), which has a very thick wall. The top of each of these lengths of hose has a hook end, something you should find readily in any hardware store. The second photo below shows how I used a short length of 3/4" PVC pipe to join a hook end to a straight length of the washing machine hose.

After hooking the end of a hose over the side of the tank, I used a long piece of twist tie to secure it in place on the handle of the trash can. Before I did this it unhooked itself a couple of times and you can guess what happened.

If you heed my advice and build a safety overflow at the top of the tank, you will have a hose going from the upper outlet to your drain. It may not be straight forward to have your overflow hose enter the drain along side the washing machine outlet hose, but it shouldn't be too difficult to figure out a way to do it.

Step 6: A Couple More Things and You'll Be Ready to Go...

Here's another safety feature to add: Hang a length of the same chain used to hang the platform between the two front chains. This will prevent the tank from sliding off of the shelf in the event of an earthquake (Shown in Step 7 Photo).

And, here's another improvement that I just thought of: The rinse water has a fair amount of lint in it. It doesn't cause any harm, but I'm going to hang a large piece of fiberglass window screen across the top of the tank and beneath the washing machine hose. With such a large surface area, I should only have to clean the screen every month or two, and it should remove most of the lint from the water.

Step 7: Using the Laundry Water Recycler

At this step, you should have everything put together and ready to go. There are two positions of the ball valves that I call Positions 1 and 2. Position 1 has the drain valve open and the tank valve closed. This is how the valves should be when you start a load.

After putting your clothes and detergent in, if there is no water in the tank, then just let your machine fill up as it normally does. If there is water in the tank, then then fill up the washer with that water. I tried putting a faucet on the end of the hose, but this slowed the flow down way too much. With the 1-1/4" corrugated hose, the water flows out VERY quickly. Here's how you do it: Take a small piece of clothing, like a t-shirt or underwear and place it tightly over the mouth of the hose (we keep a step stool by the washer so we can reach up there easily). Slowly, bring the end of the hose down into the washer basin. When you have the end of the hose in position, remove the piece of clothing and the water will come gushing out.

If you need to stop the flow of water before the tank is empty (because, say, you are doing a small load of laundry), SLOWLY place the piece of clothing back over the hose, gradually cutting off the flow (If you do it quickly, you'll probably get sprayed with water). When the flow has stopped completely, keep pressure on the end of the hose and lift it up slowly. As soon as it is above the level of the tank water, the pressure will release and you can then put the end of the hose back on its hook. If you have introduced enough water for your load setting (small, medium, large etc), then the sensor in your machine will know not to add any more water and it will automatically start washing (mine starts as soon as I close the door).

One reader has suggested that you could avoid all this trouble by installing a ball valve on the hose itself. That would probably work just fine, except that these valves take so much force to turn on and off. I think, if one could either get a ball valve that doesn't turn with such difficulty, or add a permanent lever to the handle, this would be a good addition to the project.

You will want to time how long it takes for your washer to complete the washing portion of the cycle, pump the dirty water out, spin, and then start filling up with the rinse water. In my case, as soon as the washing starts, we start a kitchen timer set at 18-20 minutes.

When the timer rings, it's time to change the valves to position 2, so water will be pumped into the tank at the end of the rinse.

At the end of the load, return the valves back to position 1, so they are ready for the next load. If you forget, and the person doing the next load also forgets to check for position 1, then the tank will overflow. Since you have put in the safety overflow :) you will not flood your house, but you will mix in dirtier, soapier water with the rinse water.

Step 8: Make It User Friendly for Your Household

There are two other people in my household, both of whom think they are not mechanically inclined (Personally, I think that they just lack experience with mechanical things, but anyway, that's beyond the scope of this project). In order to get them to by in to using the system, I tried to make it as user friendly as I could. To their credit, both of these people have stuck with it, enduring flooding, and occasionally being sprayed with water. Now the system works very reliably, and it's been months since we have had any "incidents".

I gave them both lessons in how to use the LWR, and I also posted a set of instructions (1st photo below) with little diagrams to how the valves should be turned. These are the instructions:

1. Before doing a load of laundry, check that the valves are in position 1.
2. Put your laundry into the washer and fill it up to an appropriate level (see Step 8 for details on this)
3. Start your wash cycle and set the kitchen time to 20 minutes (this is the time on our washer when the wash water has been expelled, and the machine is filling up with rinse water. Your time may be different).
4. When the timer sounds, switch the valves to position 2.
5. After the load is finished, return the valves to position 1.

Here are some extras things that I have done/made to make use of the LWR easier:

1. If you look closely at the photo of the plumbing in Step 5, you'll see a black dot on each valve handle and two black dots on each leg of the "Y" (made with a permanent marker). These help us to know which way to turn the valves. The black dot on each handle should always line up with one of the other black dots.

2. Ball Valve Wrench (2nd and 3rd photos below)
It turns out that these ball valves can take quit a lot of strength to turn, so I made a valve wrench out of a length of 2" ABS pipe. As you can see from the photo below, there are two 3/8" slots cut with a hacksaw into the end of the pipe. To use the wrench, just slip the slots over the red valve handle and turn.

3. Tank Fill Meter (4th photo)
This meter is made from the top of a quart yogurt container and a popsicle stick and it shows (approximately) how much water is left in the tank after a load. This can be helpful to the next person doing the wash. For example, if there is a "Super" amount of water in the tank and they are doing a "Small" load, they will know that they have to stop the flow of water themselves.

4. Laundry Load Measuring Tool (5th and 6th)
When you are releasing water from the tank into the machine, how do you know when you have enough? This tool sets in the top of the basin and has a measuring stick that hangs down. There are four lock nuts on the stick that show the water level for each of the four load sizes. I determined the locations of these nuts by observing the maximum water level for each type of load. As I'm filling the washer from the tank hose, I make sure to soak all of the clothes well, so the clothing sinks down to its natural, wet level. Then, I choose a load size that will cover the clothing with a couple of inches of water.

Step 9: Possible Future Improvements

In my system, I still need to add an overflow outlet and fasten the platform to the wall.

It would be possible to use electric solenoid valves, controlled automatically, instead of the manual ball valves. However, I don't think it is worth the expense and effort and by now we are all used to changing the valves manually. This idea has also been patented.

I would like to use larger diameter hose than the washing machine hose at the ends of my plumbing, and pipe fittings larger than 3/4 inch, as that would ease the work load of the washer pump and consume less electricity.

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    6 years ago

    GOOD JOB...!!!


    6 years ago

    Is it possible to tie in to the wash cycle timer to automate the valves? I would assume an older machine would be easier to do this with.


    7 years ago

    for those that want to try.. the patent has run out without renewal :-D

    yes the way to do it would be to use solenoids from old machines... front loaders rinse 3 times and only add softner to last rinse...

    so with some logic both the wash water and the 2 first rinses can be reused...

    an arduino can do many things :-D

    PS... the daft comment about a sud saver is a bit misplaced as i could not find one from new anywhere


    Reply 7 years ago

    I don't like your screw-in anchors in your floor joists. As a principle they must damage the integrity of the joist much more than drilling laterally through the joist and using bolts. Second, I have had these hooks straighten out as well as pull out. They're just not safe IMO for this application.


    7 years ago on Introduction

    Combine this with a suds saver machine and you will create more water than you used.


    8 years ago on Step 7

    This seems like a great way to save water, but it defeats the purpose of owning a modern automatic washer. Unless some way could be found to automate this whole system, it wouldn't be worth it. I have four kids, and there are several loads of laundry done each day in our house. We'd have to install new stairs, because all the running up and down into the basement that this system would require would wear out the ones we have now. LOL


    Reply 8 years ago on Step 7

    I appreciate your comment. It does require extra work to run this system, so it's probably only for energy saver nuts like me. However, since you have four kids, they probably have plenty of energy to run up and down the stairs to change the valves :)

    The whole thing could be automated, but it would be a pretty involved project.


    Reply 8 years ago on Step 7

    How would you go about it?

    It is important to make sure that you have the drain valve open or that the holding tank's fill hose does not become submerged during the washer's agitation cycle. Whirlpool/Kenmore topload models have a reversible motor that, during agitate, drives the water pump backwards to draw air through the drain hose in order to generate air bubbles that rise from the bottom of the tub, which increases the efficiency of the machine's wash action. You may also want to lower the height of the holding tank so the fill hose is within the manufacturer's recommendation. They give this specification to minimize the water that returns back from the hose, and into the outer tub beneath the metal wash basket once the drain cycle ends.


    Reply 8 years ago on Introduction

    In my setup, the fill hose is always above the tank water level. I probably am higher than the manufacturer's recommendation, but that doesn't seem to have caused any harm to the machine.

    Thanks for your comments.


    13 years ago on Step 6

    And since we're all being so green, you'll take that lint filled stocking, turn it inside out, removing the acumulated lint, lay it length ways on a large tree limb to dry,and leave it for the birds to use as nest lining materiel. This instruct makes me wish I had a top loader instead of my front. Wonder if a person could convert this to a gray water garden waterer? University of Arizona, you said?


    Reply 9 years ago on Introduction

    they have done it but uill need a 6 - 8 stage stage water filter to remove all those nasty chems from the out bound water flow

    Callum Snowden
    Callum Snowden

    Reply 12 years ago on Step 6

    You could probably use this with a front loader by connecting the water output of the tank to the cold-water input of the washer and just cap off the hot water input and just do a cold wash :P


    12 years ago on Introduction

    Well, this idea is with good intentions, but.... first, most washing machine manufacturers advise consumers that the drain hose should not have to drain more than approx. 66" off the floor. That is not even 6'. Failure to adhere to that will cause either premature pump wear or it just won't pump at all. take a look at this pic. No go. The stand pipe is at least 7' off the floor, as is the top of the can. second, Sudsaver washers did not use the RINSE water, they used the wash water because it was most likely warmer and had soap already in it. The process of draining the wash water into a holding tub allowed the heavy particles to settle. When the water was sucked back into the machine, the hose, which had an extension on the bottom to be sure it couldn't suck up crud on the bottom, would get only the 'best' of the water. We had a Whirlpool Suds saver. My aunt had a Lady Kenmore Sudsaver. Back when, everyone had a sudsaver. They haven't really been made for about 25 years. You would occasionally see one model, out of a manufacturers line maybe. That was through the 90s. third- you don't want to reuse rinse water as wash water, especially if you have used fabric softener. Fabric softener has a non-sudsing agent that will neutralize detergents. In other words render the detergent useless. fourth- the installation in this pic is not practical. Wouldn't one hit their head when trying to operate controls or load the machine? fifth- the installation, as pictured, does not seem to have any allowance for cleaning the can or for providing for an overflow, in case it should get too full. sixth- buy a front loader. they use 1/3 the amount of water that these old style toploaders use and 1/2 the electricity. They are so quiet, especially on a cement floor. And they get the clothes CLEANER. They have been coming down in price. I recently bought a brand new Whirlpool Sport (kind of bottom of the line model) for $440 . This was for an elderly relative. I have a Whirlpool 9200 and love it. seventh- if you want to recycle any washing machines water, do as someone already mentioned and send it to your garden, or even just your lawn. If you are on a sewer system, allowing gray water to replenish our dropping aquafur water levels and taking the burden off the sewage treatment plants is significant. Have a good day.


    Reply 12 years ago on Introduction

    Thanks for your critiques. My replies are below. With all due respect, we have been using this system for almost two years and have saved thousands of gallons of fresh water by doing so.

    1. The previous owner of my house created a basement and arranged the washing machine as it is, with the 7 foot vertical distance for pumping. While I agree that this is not ideal, the washing machine has always worked just fine under these conditions. Perhaps the pump is forced to work harder and uses more energy, but it does work and was in place before I added the gray water system. More importantly, as I state in the instructable, most houses don't have their washers in this configuration and would therefore not face this issue. In fact, I think most houses with the washer above garden level could create this system with no auxiliary pump.

    2. Thanks for the clarification on how the Sudsaver machine worked.

    3. We don't use fabric softener in my household (I don't think you would want to feed that to plants), but I will add a warning in the instructable to not use it in this system (same goes for chlorine bleach, powdered detergents etc.). There are other web pages that get into what laundry products you can and can't water plants with. All that said, I think the rinse water is a lot cleaner. The wash water has all of the dirt from the previous load suspended in it (good for plants, however). Bottom line - we are satisfied with the way our laundry comes out.

    4. As a clearly state in the instructable, we have been using this system for a long time. That complaint has never come up.

    5. The can can easily be cleaned - just take it down when it's empty. There is an accumulation of lint inside the can and I really should add a lint filter, but I haven't done so yet. I also state in the instructable that I should put in an overflow system and I recommend that anyone who makes this project do so as well. I just haven't gotten around to it. In over a year of operation I think we've had two or three overflows, and none very recently.

    6. Read my introduction. Not everyone is ready to (or should) immediately buy a front loader, but eventually we should all get them.

    7. Agreed - see my other instructable ( We now only use the tank during the rainy season, when watering the garden is unnecessary.


    Reply 9 years ago on Introduction

    use arm &hammer baking soda on alredy cleaned clothing itill keep it clean. if it stained however uill have to use those nasty stain fighters then. even then most of them dont crud to the stain.


    13 years ago on Introduction

    Very nice project. Sadly they used to sell washing machines here that did this very thing, but I have not seen one in a long time.


    Reply 13 years ago on Introduction

    I have a Sud-Saver top loader as well (came with my house). It has two drain tubes, each going to separate sinks in the stationary tub. If you flip the switch to "drain", it drains like a normal washer into the right side. If you flip it to "save", it drains into the left side of the tub, where the drain tube stretches to the bottom of the tub. You have to remember to put the plug in the tub drain, obviously. Then when you start your next load, you turn the main washer knob to "sud saver", pull the knob out, and it starts sucking in the gray water. Once that's done, you turn the knob to whatever cycle you want, and start it like normal.


    Reply 13 years ago on Introduction

    Would you post a photo of this washing machine? I'm very curious about how it looks.