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:

Camplux 5L 1.32 GPM Outdoor Portable Propane Tankless Water Heater
GASPRO 1lb Propane Adapter for Disposable Throwaway Cylinder
Seaflo 12V 1.2 GPM 35 PSI Water Pressure Diaphragm Pump
Besteek 12V 15A Male Plug Cigarette Lighter Adapter Power Supply Cord with 3M/10FT Cable
EPAuto 12V 12' Foot Heavy Duty Extension Cord with Cigarette Lighter Plug Socket
2 each - 1/2" Female MIP to 3/4" Male Garden Hose adapter
2 each 3/4" Garden Hose Female to Male Elbow adapter
2 each 3/4" Garden Hose Male to 3/8" Barb Adapter
2 each 1/2" MIP Male to 3/8" Barb Adapter
Package of Hose Clamps 1/4"-5/8"
10ft of 5/8" OD Vinyl Hose
Misc Screws & Bolts for as required for assembly

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!

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.
Next, string together your brass adapters until you get to male barbs on both your heater input and output
A short hose goes from the output of your pump to the input of your water heater (secure with hose clamps as well)
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!)
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:

Attach propane bottle to GasPro ONLY after ensuring it is already firmly attached to the regulator!
Load two D Batteries into the battery holder of the Heater (take care you get the polarity right!)
Double check that all hose clamps are well seated and tight
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!)
Make sure the Shower Wand is turned OFF
Make sure the Heater Handle is pushed down out of the way of the hot gases rising from top of the heater
Set the heater water flow in the middle of the dial, and the gas to its lowest setting
Plug the car adapter into your vehicle or 12V battery pack.. the pump will begin immediately
Quickly grab the shower wand and open it up to allow for the flow of water...
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.
The Heater should immediately respond to the flow of water by sparking up a flame and begin heating the water.
Water will shortly flow out of the heater and down the hose to the wand.
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.
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.
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!