Portable Demand Use Hot Water Shower




About: Peter Valentine

This project was inspired by the desire to "car camp" in my Toyota Prius. I had been looking at teardrop trailers and other small trailers that could be towed by a Prius when I realized that basically they were all small sleeping "coffins" that cost from $3K to $20K+ and really they offered no amenities other than a bed to sleep in and perhaps a shelf to cook on! The Prius had room to sleep inside and the added bonus of air-conditioning built in! (A Prius can run air conditioning all night long for about a gallon of gas!).

What was missing was the ability to take a shower... not until you up-size to a large RV do you get a shower built-in, and of course the gas mileage is VERY poor! If I had to plan my trips around staying some nights at hotels or high-end campgrounds with showers, it would limit my travel plans and of course increase the expense significantly too.

Now I have built several camping showers for heavy duty camping at large events (SCA, etc). But I thought I would take what I have learned and boil it down to a minimalist version of my SCA Kitchen hot water system (which supports feasts of 30+ guests, dish washing & showers).

This project was designed for car camping but it also works for a multitude of group camping events as well. (Like Burning Man, Outfitting, SCA, etc.)

Step 1: Materials

This build is mostly about the parts... you can mount them on or in whatever form factor you desire. This particular build focused on making a compact unit that I could simply carry out and set next to a small privacy tent and take a shower whenever I felt like it... or set it next to a camp kitchen and get continuous hot running water for washing dishes... or rinsing off a muddy dog... etc!

OK, so here are the parts that I used in no particular order:

Note that the brass hose fittings and adapters is up to you and what you can source locally. Every hardware store has a different selection and sometimes you have to get very creative about how you adapt between different sizes of hose!

Step 2: Its All About the Brass!

So likely the most challenging part of this project is getting the brass right... Once your big items come in (Heater & Pump) I suggest that you take them with you to the hardware store and begin the hour long process of finding the right adapters to put it all together. Maybe you are lucky the first time out... but getting the gender of each connector and 90 deg bend correct can be devilish! (It took me two trips!)

Remember the goal here is to adapt from the brass fittings on the tank to a nice hose that can lead to your shower wand. I had to go from MIP to garden hose and back to MIP AND barb connections! If you are not in a Rural Area with limited selection, likely you can do better!

  1. First, you will need a hose coming in from your water source that connects to your barbed input on the pump (I like to put a brass barbed adapter on the end that drops into water can so that the end of the hose does not curl up and out of the water but stays in the bottom of the tank!) Make sure the length is sufficient to reach up into and to the bottom of your water source/tank! Use a Hose Clamp to connect the hose securely to the barb on the input side of your pump.
  2. Next, string together your brass adapters until you get to male barbs on both your heater input and output
  3. A short hose goes from the output of your pump to the input of your water heater (secure with hose clamps as well)
  4. A longer hose goes from the barb on your heaters output to a Barb->1.2" MIP adapter which is screwed into the end of your shower wands hose. (You may need teflon tape here to ensure a leak proof fit, test the fit in the store before you leave!)
  5. Finally the GasPro Adapter is used to adapt your regulator to use the smaller tank size (You do not need this if your are going to use a 5lb-20lb tank as your propane source)

Step 3: Building the Frame

Now I wanted to be able to grab the whole thing by the handle and simply walk around with it... so I built an inverted T frame to hold all the parts... you could just as easily enclose it in a box, built it into a sink, etc.

I grabbed some spare 1/2" plywood I had lying about the shop and after measuring the heater determined that I needed about 10 1/2" wide strip (to pass between the handle attachment points). Likewise I needed several inches below the tank to be able to make all the plumbing connections... 21 inches high did the trick.

After cutting the "back" on a table saw, I notched it where the screws for the handles would be in the way and marked holes for mounting (based upon the mounting holes already in the metal frame of the heater)

I also cut a base board 10.5" x 14" long and rounded the corners. This was then glued, clamped and screwed to the back to create a simple T shape that would allow me to hang the heater on one side and the pump and propane tank on the other.

I then cut some reinforcing triangles and glued, clamped and screwed them into place to keep the back straight and give the whole thing strength.

Finally I drilled a 1" and 5/8" hole into the back to allow the Gas Pipe (with nipple) and the pressurized water to pass through to the heater.

Step 4: Assembly

Putting it all together is basically a matter of connecting up all the parts correctly:

  • Start by soldering the 12V extension with the cigarette lighter adapter (you will need to cut off the eyelets and strip back the wire). Note: DO NOT use electrical tape, use heat shrink to seal each line individually. electrical tape just comes apart in the heat! If you are allergic to soldering, you can check at the auto parts store to find solderless crimping connectors that should do the trick.
  • Mount the Pump using bolts, washers & nylon nuts to the back, take care not to pinch the electrical line
  • Mount the Heater to the opposite side of the back with bolts backed by washers and nylon nuts (so they cannot work loose)
  • Run the gas line through the hole in the back and attach it to the Gas connection on the bottom of the heater
  • Connect the input hose to the input side of the pump using a hose clamp
  • Connect a short hose from the output barb of the pump to the input of the heater (again use clamps)
  • Connect the output of the heater to the hose leading to the shower wand.
  • Screw the GasPro Adapter into the Regulator
    IMPORTANT SAFETY TIP!!! DO NOT screw the GasPro into the bottle first!!! Doing so would vent the entire contents of the Propane bottle and could result in an EXPLOSION! Follow the GasPro instructions CAREFULLY!
  • I 3D printed a few hold down clamps for the hoses, you could find appropriate parts at the hardware store that serve the same purpose (neaten it up a bit).

Step 5: Operation

OK here is the basic operation:

  1. Attach propane bottle to GasPro ONLY after ensuring it is already firmly attached to the regulator!
  2. Load two D Batteries into the battery holder of the Heater (take care you get the polarity right!)
  3. Double check that all hose clamps are well seated and tight
  4. Insert the Input Hose into your water supply... make sure that the end of the hose is in the BOTTOM of the tank and cannot float/curl up to the top (a heavy brass fitting on the end of the hose does the trick for me!)
  5. Make sure the Shower Wand is turned OFF
  6. Make sure the Heater Handle is pushed down out of the way of the hot gases rising from top of the heater
  7. Set the heater water flow in the middle of the dial, and the gas to its lowest setting
  8. Plug the car adapter into your vehicle or 12V battery pack.. the pump will begin immediately
  9. Quickly grab the shower wand and open it up to allow for the flow of water...
  10. The pump should prime itself (pull water from the tank into itself) and then you should see water flow from the pump into the heater.
  11. The Heater should immediately respond to the flow of water by sparking up a flame and begin heating the water.
  12. Water will shortly flow out of the heater and down the hose to the wand.
  13. It will take a few second for water to begin to heat up... now is the time to play with the flow and gas settings on the heater.
  14. Turning off the switch on the Shower Wand will halt the flow of water and the heater should immediately turn off (it will still be hot but flames should be extinguished). In a few seconds the pump will come to full pressure and likewise turn off.
  15. This is when all of your leaks will start spurting water... now run around screaming while tightening fittings and hose clamps... if you don't get soaked the first time you turn it on... congratulations you did better than I did!

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    12 Discussions


    1 year ago

    The solar water heatwer showers only work well when exposed to a good warm sun for a few hours... so no good for coole mornings or winter weather. The Ivation sounds like a good idea as long as you have a source to heat up your water. There are several similar models on Amazon in the $30-40 range. This model is better for larger parties though. Still need a pop-up shower tent. Could supply all your hot water needs, not just a shower, and temp is adjustable. I'd use one of those heaters if I were building my own camper. A small pop-up tent camper would be nice to tow. I've always wanted to remodel a small 12-15' camper and have little more than a bed and bathroom... a motel room on wheels. Cook and such outside, still have the convenience of your own bathroom and a comfortable bed with AC and heat! Maybe have the bed fold up into a couch, or use a sleeper sofa in front instead of a bed... but I'm getting off subject!


    1 year ago

    Rather than have to carry the water heater around with you, stop by a yard sale somewhere and get yourself a wheeled carrier that's used for golf bags. You should be able to strap the entire thing on it, and portability takes on a whole new meaning.


    1 year ago

    I was going to do that but chose instead to get a s/h Volvo "gas cooler" from e-bay which is a heat exchanger (car part) Exhaust gas passes from my generator through the small tubes heating the water in the jacket around them. My system is considerably more complex because I fitted out a Sprinter van with a water boiler and water filled radiators (and granite floor with underfloor heating!). I use the generator to top up my batteries when the 400W solar panels are not functioning over periods of poor winter weather. Basically I'm using as much energy as I can from burning fossil fuel. The granite underfloor hearing is partly comfort but also a heat sink for the cold side of the thermoelectric generator I intend fitting when I have some spare cash (such as the Devilwatt).


    1 year ago

    If you are going to sleep in your car for the air conditioning while it is running, please buy a 9V carbon monoxide detector. I was at a funeral yesterday for a friend who passed away while she was taking a nap before driving home after working a double shift - carbon monoxide poisoning. She wasn't in a garage or under an enclosure - just in her car with the windows rolled up and the air conditioner on. Carbon monoxide is a silent, tasteless, colorless, odorless, deadly gas.

    I know the sleeping isn't the focus of your 'able, but you make a point of it in your intro. And it's an issue that is rightfully in the front of mind right now.

    1 reply

    Reply 1 year ago

    That's just awful that that happened, her family should be hiring a lawyer and suing the car manufacture. Under normal conditions there should be zero exhaust in the passenger compartment of a vehicle.


    1 year ago

    Its a great build but seems a bit over complicated. Have you considered a sun shower? Its basically a bag of water you hang in the sun for 5 minutes and then take your shower. Since the bag is portable, the shower part can be anywhere. No pump or electricity because it gravity feeds.



    Question 1 year ago

    Great build! How much use do you get out of one of the gas cylinder and how much current does the whole thing draw on average during a shower?

    1 answer

    Answer 1 year ago

    yes I would like to know this also.


    1 year ago

    I camped out of my Prius a bunch and still do on occasion... thankfully, I have no sweat glands and not much for sebaceous... though do have where I have hair so I can get away with towel wash. I was thinking making one of the flat black painted solar PVC pipes that can be pressurized also with a bike or whatever pump if I have a partner camping though. I did think about this idea also, though more-so for the farm to preheat the water since a girlfriend of mine uses on their farm for cold weather water preheating when the solar preheating pond isn't hot enough. Neat design and thanks for sharing. Be careful with the tanks if you refill since I think a brass safety cap needs to be designed and marketed since I've found even new tanks can leak.


    1 year ago

    Did you think about adding an on/off switch in your power feed so that you don't have to worry about draining the battery or climbing in/out of the car while getting ready/after your shower? I have some friends that built a similar system, but they put a timer on it so that it doesn't drain the deep cycle battery if someone forgets to turn it off when they're done.


    1 year ago

    If you can get along without the satisfaction of building this remarkable unit, there is a simpler way.
    Order a unit called Ivation battery powered shower from Amazon. ($35) It consists of a baseball sized pump and rechargeable battery (all in a waterproof shell) with a six foot hose connected to a shower wand at the other end. The pump end is equipped with a recharging port (110 v or usb) and an on/off switch.
    Next, get a SS stock pot, about 5 gallon size.
    Fill the pot with water that has been heated by the sun or heat it on top of any stove, even a tiny backpack stove.
    Stick the pump unit in the stock pot. Press the button and take a shower. you can get 6-10 showers between charges.

    This is the only means for taking a shower that I have had for the past two years and it has served me well. (I built a regular shower stall in both my winter and summer homes, neither of which have running water, and use this self-contained system therein).

    With the Ivation you can also take a cold shower from any water source (stream, lake, etc.) available. Simply press the button and put the pump in the water. It has a small filter to keep out the debris.

    1 reply

    Reply 1 year ago

    All thats need for these heaters is a 1 GPM flow rate and up. I've had 3 of them so far and am very familiar. I currently have mines mounted on a handtruck with a mounted milk crate holding the 15# tank.

    Awesome heaters and great customer service from them to boot.