Building an outdoor, gravity-fed, solar-heated shower
Over the summer we designed, built, and tweaked an outdoor, gravity-fed, solar-heated shower to minimize use of our oil furnace. Read on to learn how we did it and what you should look for when making your own!
[Pictures to come soon — I just have to get out on the roof one of these days! – October 8, 2008]
[I got pictures but it was during a break in the snowy weather so the system looks a little ‘rag tag’. – December 16, 2008]
Situation: Interested in trimming ordinary household costs, we decided to exploit the summertime weather and build a solar-heated, gravity-fed, outdoor shower for use in the evenings.
Goal: Build a contraption that heats a suitable amount of water (for ~10 minutes of shower time) to a suitable temperature (~98*F or hotter) on a mostly sunny day with normal outdoor temperatures in the low 70s to high 80s. This type of weather is relatively common in the mountains of central Pennsylvania for about 4 months a year. Most of the shower’s materials are to come from objects lying about the property.
Outcome: An outdoor shower incorporating a pumpless solar water heater was developed that worked very well. Some tubing and spraypaint aside, all materials were repurposed from other projects or rescued from being junked. The system incorporates two elevated topless coolers covered with a single pane of glass, connected via vinyl tubing to a watering can’s fountain head. The water flow is controlled by a rubberband that maintains a kink in the tubing. The rubberband/kink is located within arm’s reach, near the fountain head. The water temperature has been observed to be about 20-30*F above the day’s high temperature, even on partially cloudy days. The shower has enough water for a 10 minute shower.
Forward-thinking: This project’s dual-cooler-based solar water heater design is easily expandable to allow for either (a) greater volume of water at a consistent temperature, or (b) the same volume of water but at a higher temperature. This can be achieved by adding more coolers to the system. To achieve (a), add water to the additional coolers; to achieve (b), allow the water from the original pair of coolers to flow into the additional coolers. Less water per cooler allows for higher water temperatures.
How it is done:
The solar water heater system
The area where the gravity-fed solar water heater is to be placed must meet some requirements:
- The containers should have a clear view of the south to catch the sun for as long as possible throughout the day. Keep the containers out of the way of any shadows from nearby trees or structures.
- The containers must be elevated at least several feet higher than the showerhead to ensure adequate pressure is achieved to ‘push’ water out of the showerhead with some force similar to a typical indoor shower.
- There must be a way to refill the containers when empty. If an outdoor spigot is nearby you can refill with a garden hose. Otherwise, get a bucket or two.
The high-level design of the gravity-fed solar-heated shower system is to store some water in a sunny area that is elevated higher than a showerhead. The showerhead itself is elevated higher than you because you stand under it to get wet. Unless you’re trying to build a sandy-foot-washer or bidet or something…
A large, old, broken cooler is recovered from a junk pile and cleaned with soap and water to remove many years’ worth of accumulated muck.
The cooler’s lid is removed because it is not needed. Then the entire cooler, inside and out, is painted with flat black spraypaint. The drain nozzle on the cooler is removed and replaced with a ½” brass nipple that is fastened into place with a generous amount of aquarium glue.
A second cooler is prepared in similar fashion. †‡
† – The how-to is greatly abbreviated to help you build your own solar water heater. Our solar water heater system went through several reconfigurations (not documented here) over a month’s time before we settled on the current form.
‡ – Herein, the cooler’s will be referred to as containers to minimize confusion. (e.g. “The cooler is a solar water heater — What?!”)
A single pane of cracked window glass is found. After cleaning the smudges off to ensure that maximum light passes through the glass, some duct tape is applied over the cracked sections to minimize the danger of getting cut.
Since only one pane of glass is found, and since the glass must act as the lid of the water containers, the containers must be placed so that the top of each container is level with the other. A mounting system is devised that keeps the containers level and the glass pane secure while perched atop a 12 foot slanted roof. By using variously-shaped lumber and two old straps with hooks, the glass pane is held semi-securely to the tops of both containers, which rest on top of some wood, which doesn’t budge against the sandpaper-like roof shingles.
When filled half-way with water and a dozen bricks (see next paragraph), the containers and glass do not move at all. Our setup survived thunderstorms with 40 mile per hour gusts of wind.
Since the key to heating water is surface area, we got to thinking about how to improve the solar heating system. We observed that early on a summer day the bricks on our sunny walkway would be quite warm. So get a dozen old bricks, wash off the spiderwebs and rocks, and place them along the bottom of the large water container, stacked two bricks high.
Put 8 bricks in the small water container. By having bricks in the containers, they will absorb heat from the sunlight and conduct the heat to more water, especially the water that is in a shadowy part of the containers. The ‘brick trick’ seems to help keep all of the water at a constant warm temperature instead of having the first half of a shower be cool and the second half be warm, since the first half of the water supply was in the shade at the bottom of the water container and the second half was higher up in the container where the sunlight hit the longest.
To refill the containers when they get low, we opted to use a nearby outdoor spigot with an old garden hose. Refilling the containers with buckets is another option but our containers were out of reach on top of a roof. Trying to get a bucket of water up there could have been dangerous. The garden hose worked very well because the one end could be left permanently sandwiched between the glass pane and the edge of one of the containers. (Only one container needs to have a garden hose because when filling one with water, both containers will ‘share’ the water through the T-connector and the water levels will be mostly equal after 10 minutes.) The other end of the garden hose was strung down to the spigot, about 10 feet below. So when the containers need filled, just screw the garden hose into the spigot, turn the spigot on, wait 2 minutes, turn off the spigot, and unscrew the hose. Watch out for the water that will spray everywhere when unscrewing the hose, since there is a 10 foot column of water that must rush out.
With the containers and glass held securely to the roof, the next step is to get the tubing and showerhead set up. Several feet of transparent flexible tubing (3/8″ inner diameter (“ID”), ½” outer diameter (“OD”)) is utilized because it was lying around from my liquid-cooled computer experiment from 6 years ago. Due to the ~12 foot distance separating the water containers from the shower head, we purchased 30 feet of black vinyl tubing (3/8″ ID, ½” OD) to connect everything together. With a dual-container setup, we used a T-shaped 3/8″ ID polyethylene joint to connect each container’s nipple to one central tube, which then transports the warm water over and down to the showerhead.
The showerhead is from an old watering can and originally found utility as part of the ‘bong evaporator’ computer cooling system (again from my 6 year old experiment). Shove a 1/2″ brass nipple into the end of the showerhead and duct tape the two pieces together. No need to waterproof the connection because it’s a showerhead after all – water droplets are preferred! The brass nipple is then attached to the end of the tubing coming from the T-connector by the dual water containers.
The shower location must have a way to hang the showerhead above your head. For our situation, the unfinished deck had a spare board which I projected over the edge of the upper deck’s flooring. Using yarn, tie a loop around the tubing and another loop around the overhead board. We ran into some unwanted kinking because the weight of the showerhead would bend the tubing where the yarn was looped around the tubing. To address this, get a foot of neoprene pipe insulation and wrap it around the tubing and then wrap the yarn around the insulation.
If you have leftover neoprene, wrap it around stuff that might hurt you while showering, because showering outdoors without paying a penny can lull one into a state of unaware peacefulness. We put neoprene around a large metal hook used for hanging plants.
The shower is controlled by kinking/unkinking a section of tubing near eye level. When kinked, water cannot pass into the showerhead. Many things can be used to kink the hose. We use a rubberband or a paper bundle clip thingy.
For more pictures of the solar-heated, gravity-fed, outdoor shower, check out our photo gallery.
Have you built your own system? Tell us about it in the comments below or sends us some pics!