Solar Outdoor Shower

for now, there is no intro. it disappeared.

this instructable is a guide to create an outdoor shower and batch solar water heater

It seemed practical to construct the shower against the wall of my house. This provides pre-existing structural support and eliminates the need to dig trenches for the plumbing, as we ran the 3/4" PVC in the eave from the spigot on the side of the house. You may want to try to select a location that is nearer to the spigot. Obviously, constructing the shower against the wall of your home isn't necessary at all, but I felt there were a few reasons to do so.

This particular shower occupies a 5.5' x 5.5' area. The deck of the shower itself is more like 4.5' x 4.5'. Once you select the size and a space that will accommodate, you can begin to prepare the area. Rather than building a drainage system to carry the water elsewhere, I dug a hole about 2' deep in the 5.5' x 5.5' area which I would fill with large gravel later in order for the water to drain clean. The water permeates the large gravel instead of building up, or worse, building up in one area and causing the wood to rot.

So, find your spot, on the side of your existing structure (or not), and dig. Here in San Marcos, TX my backyard is a rock farm, so it was very interesting getting this hole dug. I attempted to dig a nice square with a level bottom. This is where the chassis which holds the poles will sit.

tl;dr;

1 Select Location
2 Dig 5'x5'x2' pit
3 Build square chassis from 2x4s to fit in the base of the pit

Done digging? Build a chassis which will support the poles and act as part of the form for the concrete which will set the poles into position. We made a square of 2x4's which sits nicely in the bottom of the hole. In each inside corner of the chassis we placed a board to close in the triangle to complete each form. As you can see, we only used three posts since we will use the house to support the remaining corner. You may be able to get away with only 2 posts if you have a wall that is big enough, or possibly even one if you construct your shower in a corner. See what I did there?

We made sure the posts were level and right with each other and set the posts in three of the corners with quikrete using the chassis and corner boards as the form for the concrete. Before we poured the concrete, the posts were fastened to the chassis with large screws. To keep the posts from moving once we got them right with each other and the house, we stabilized them with temporary boards between each other while the concrete was setting. I would highly recommend setting the poles with some sort of concrete - you don't want to have to worry about the water damaging the chassis over time and this improves the structural integrity of the shower.

The shower pit is ultimately the foundation of the structure, that is the shower, as well as constituting a draining mechanism. This is where you would need to implement your method to catch the water if you decide to capture and reuse your shower water.

If your chassis and poles are set, you will not need to access the space inside the hole anymore. The remaining steps will only require the support of those poles or the house. This means the hole can now be filled with gravel. I used about 1.5 cubic yards of large gravel.

I thought gravel made a nice base, and certainly drains much better than dirt. This way, you won't have puddles of water gathering around your shower, and the subsequent fungus or unwanted organisms.

Now that you have the gravel foundation, create and fasten a deck frame/base to the posts/existing structure. Make certain that this frame is level. Your deck and walls will be attached to this frame.

The walls are constructed from 2x4's and will support the canvas walls and in this case, an old window. I like to think the window adds some nice character. And like I said, up-cycling materials will make your project inherently unique.

I picked up a few old 6 panel windows from someone for free off craigslist a while back and decided to use one of them for the outer wall. I will put a small curtain on it someday. For now it works without, as my gender seems to feel comfortable obscured from the waist up. The walls come in the next section.

As you can see in the last photo in this section, the deck base has a coat of waterproofing stain. Any wood that will be exposed to varying temperatures and moisture will always be better off protected. Especially while you're in college.

This deck was made from 2x4's as well. We were sure to sand one side till they were very smooth as this would be the floor our precious bare feet would be encountering. Before setting them permanently, we measured and cut the pieces of the deck and painted all sides of all pieces that would become the deck with weatherproofing stain, which turned out to be very nice aesthetically. Once that layer of stain dried, we set the deck and applied pressure for a tight fit. Even if you apply pressure, the water drains through the deck into the gravel, which is what you want. Since we were using scrap wood, we ran out of pieces that were at least 4.5' so the remaining section was completed the opposite direction with smaller pieces we did have.

The rear canvas wall is stationary while the front curtain slides on the conduit rod. I sewed a loop in the top and bottom of the canvas for the rear wall and a loop on along only the top of the canvas for the curtain. This allows the front curtain to slide and the back remains stationary. This canvas is actually painter's throw, I think a 9' x 13' for around $12 a piece. There are many different sizes of this cheap canvas you can find at any hardware or home improvement superstore. You might even try an army surplus store to try and find some high quality canvas.

Using a conduit bender and some previously acquired skill, I bent the conduit for the curtain to fit around the post. Once I semi-permanently mounted the conduit "shower curtain" rod, I slid the conduit through the loop in the top of the canvas curtain and then proceeded to permanently secure the conduit.

I use the blue clips seen in the photo to secure the curtain to the house if it's a little too windy outside. I normally don't have to worry about this.

For the rear canvas wall, I bent 2 pieces of conduit into identical pieces and mounted them to the frame of the shower and the house, parallel to each other the entire way around the shower. This wall turned out a lot better than I thought it would.

Once the rear canvas wall and front curtain were finished, I had deliberately left a bit of space at the bottom and the top, and then cut pieces of lattice to fit in those spaces. I wanted this shower to "breathe" and I wanted to avoid closing in that space at all. The lattice was a nice option because it lets air in through the bottom and the water can find it's way through it easily.

The grey wood you see was previously a fence somewhere. I used this wood on the inside as well as the outside for the front wall. I tried to get a nice look by leaving even spaces in between each piece of wood used for the front wall. I'm not so sure it turned out as cool as I thought it would. See photos.

Now that the shower is pretty much done save the plumbing, we can look at the solar water heater and its hot box.

Some folks may not be interested in the outdoor shower, and are just looking for some direction for building their own batch solar water heater. If that's you, you found the right spot. I would probably make a separate instructable, but unfortunately I didn't take enough pictures while building the water heater box. So, I will just explain the details as best I can.

We acquired the old water heater and prepared it for its new life before constructing the shower, but this section seems to fit better here.

You won't want to build your water heater box until you know what size tank you're going to have. Since I was not going to pay a dime for the tank, the size I ended up with was a 30 gallon. At first, this seemed like too much, as I was actually trying to get an RV or mobile home size tank, i.e. 15-20 gallon. The 30 gallon tank turned out to be a very appropriate size, and allowed for multiple showerings for my good family. If you use a smaller tank, you can always shower as a group to use the hot water more efficiently. 20 square feet turned out to help us out as well. (see photos for details on how to use your shower more efficiently with group showers).

The larger capacity tank you use, the sturdier your box will need to be. Full, a 50 gallon tank would weigh 417 pounds. This 30 gallon tank weighs about 250 pounds when full. That is enough weight to support to take care to build a very sturdy water heater box. Just stick to the old american method and build everything as solid as possible, all the time. I cannot vouch for all Americans here, but I think that's how they did in the early 1900's, back when they built stuff. Before plastic and other materials that hardly be upcycled. But I digress.

Once you find a water heater to use, get the tank out of it. Remove all the insulation that is stuck to it using any means necessary without damaging the tank. A stiff wire brush, coarse steel wool and sandpaper work well for finishing. You want a mostly smooth finish as you'll be painting the tank. As far as what paint to use, you might find the following article helpful. It is a comparison of different paint's effects on temperature. There exists spray paint known as "solar selective coating", made exactly for this purpose. The study done by "Gary", shows that regular flat black paint actually had slightly better results than the Thermalox solar selective coating. That is, the flat black paint resulted in the highest temperature for the material. Keep in mind this does not mean the flat black paint helped to keep the water inside the tank hot once the sun goes down. That is a mystery maybe you can solve. See the article:

paint type vs. temperature testing

I've heard good things about SOLKOTE, too.


I used barbecue pit (high heat) paint. Looking back, it doesn't really make much sense. I don't think paint that can hold up against 1000+ degree (Fahrenheit) temperatures is necessary. Look into paints that work well for solar collectors. A photo of the painted tank is in the next step's photos. The tank is in the hot box for that photo.

Keep in mind that your batch water heater will work best if the hot water outlet is elevated. You should be able to infer from the photos that there is a riser in the bottom of the hot box, on the side where the outlet and inlet are. This works because of the dip tube inside of a water heater tank. See the image for a reference. The dip tube takes the cold water input to the "bottom" of the tank. That way, when you open the valve at the shower head, you get the hot water, and not the water that has just entered the tank. If somebody out there could design a tank for the purpose of creating a batch solar water heater, I believe that with a little bit of science you could really improve the efficiency of the tank by manipulating the way the water moves inside of it. You could do this with dip tubes and baffles I assume. I'll look into that later.

Once your tank is cleaned and painted, you will be certain of the size hot box you will need to build. Next step is the hot box itself.

a thought: you might be able to find a way to use the water heater casing as a water catchment device.

We built the hot box to be about 1'6" longer than the tank to allow room for the plumbing ( see next step) and insulation. As you can see, the hot box skeleton was built with slant on top so that it could be closed and insulated as much as possible while letting in as much solar radiation as possible. This is called a right trapezoid. So make a 3 dimensional right trapezoid that your tank will fit in with room to spare for the insulation, reflective material and plumbing. What I mean is the hypotenuse of a triangle is longer than its cathetus, therefore you should optimize the area of the glass that the sunlight will pass through. You can also "direct" the glass based on the sun's path. To determine the sun's path, watch it all day, or use the SOLight app for the iphone, because it's awesome. While building your hot box frame, be sure to incorporate the riser that the top of the tank will rest on to be elevated.

The size of your box may depend completely on what size of double pane glass you are able to come up with.

"
Tempered glass with a low iron content is preferred. Non-tempered glass in collectors can crack from the heat, and glass with a high iron content transmits less light.

Many glass shops will offer blemished or pull-outs or miss-cuts at very low prices, but will not likely stock the highest transmittance glass.

Glass is a good glazing material for solar collectors.
High transmission (low iron) tempered glass is used on the majority of commercial solar collectors.
"

If you can't get glass, there are a few alternatives for solar collector glazing. See this article.

So, once the "frame" is built, you will want to close in all sides and bottom of the hot box with plywood. All I could find was the cheap OSB stuff, but I would have used good plywood if I had the funds. Once the sides and bottom are complete, seal all the places where 2 or more pieces of wood meet with some kind of sealant. We used GREAT STUFF. Be generous with your stuff. Once your stuff is set, get out your long sleeve shirt and insulation. We used fiberglass insulation with the highest "R" value I could find. You might also use layers of water heater blankets or water heater jackets. Layer the entire inside of the box with as many layers of insulation as possible. You might want to consider using something like stiff chicken wire to keep your insulation in place while you attach the reflective material on top of the insulation. I say this because we struggled with the reflective material due to the lack of constraining the insulation. The reflective material we used was reflectix.

Looking back, I would have built a much sturdier box with handles, and used flexible pvc to get to and from the hot box. This way you could move the box into a better location according to the changing path of the sun throughout the year. Also, I went back and placed many bricks underneath the box to get it off the ground, which should help prevent the bottom from wearing out from exposure to moisture on the ground.


Frame built, riser in place, insulation and reflective material set, now time to place the tank. In addition to placing your tank, you will probably want to seal the exterior of your hot box. Do the best you can to seal the perimeter of the glass Once you get a friend to help you place the tank you should be ready to look into plumbing if you haven't already.

I know we're in the middle of building the structure. But you may find, so it goes in many projects, to begin the plumbing! Of course, if you lay your plumbing at just the right time, you will end up with something more aesthetically pleasing. If you need to, reference the basic block diagram. You probably won't learn anything from it that you didn't already know.

tl;dr: get the water from the spigot to your shower, and use a "T" joint to split the source to your solar water heater and blend valve. You will need an appropriate amount of 1/2" or 3/4" pvc, two valves, 90 degree joints, 45 degree joints, pvc glue and pvc primer.