In This Article
How Solar Outdoor Showers Work
A solar outdoor shower is simplicity itself: a black water bag or tank sits in the sun, absorbing thermal radiation and heating the water inside. When you open the valve, water flows by gravity from the bag through a showerhead to the user. No pump, no electricity, no gas connection.
The core component is the solar heating element. Options include:
- Black poly bag: 20-40 gallon collapsible bag, typically $15-30. Fastest heating but shortest lifespan (2-3 years).
- Polyethylene tank with black interior: 40-80 gallon tank, typically $40-80. Slower to heat but holds temperature better and lasts 10+ years.
- Copper coil collector: Black copper tubing connected to a storage tank. Most efficient but most complex to build.
We use a 40-gallon polyethylene tank mounted on a timber frame above the shower enclosure. This provides enough water for 2-3 showers and holds heat well into the evening.
The Design
Our requirements were specific:
- Water capacity: 40+ gallons (minimum 2 showers per fill)
- Privacy: Full-height walls on all four sides, solid door
- Temperature: 100-115°F achievable on sunny days
- Drainage: Grey water handled on-site (no septic connection)
- Cost: Under $250
We built a 4x4 foot interior shower stall with a 6-foot-tall cedar frame, corrugated polycarbonate roof for the solar collector, and cedar privacy boards on all four sides.
Materials List and Cost
| Item | Cost |
|---|---|
| 40-gallon solar heating tank | $65 |
| Cedar 2x6 lumber (24 ft) | $48 |
| Cedar 4x4 post (8 ft) | $28 |
| Cedar fence boards (12) | $24 |
| Corrugated polycarbonate roof (4x8) | $22 |
| Shower valve and showerhead | $18 |
| 1/2" brass ball valve | $8 |
| 1/2" galvanized pipe (10 ft) | $12 |
| Shower floor grate (10x10) | $10 |
| Gate latch | $6 |
| Exterior-grade screws | $14 |
| Total | $255 |
That $255 is at 2026 retail pricing for all components. If you have cedar on hand from another project — we had some of ours left over — you can shave $50 to $80 off the total.
Building the Frame
The frame is built from 4x4 cedar posts set in the ground. We dug 24-inch holes, set the posts in compacted gravel, and backfilled with concrete for permanent stability. This is an outdoor structure that needs to handle wind and weather.
Cross-bracing between the posts provides lateral rigidity. We added 2x6 horizontal rails at the top (which support the solar tank) and halfway up (which support the privacy boards).
The shower floor is a 4x4 foot cedar frame filled with 2 inches of washed gravel, topped with a 10-inch square shower floor grate. The gravel drains directly to the ground below, distributing grey water over a 4-foot radius area.
Grey Water Management
Outdoor shower drainage typically falls under grey water rules in most jurisdictions. We route our drainage through a gravel bed planted with willows, which absorb the nutrients and prevent pooling. This keeps the site odor-free and sustainable.
The Solar Tank Installation
We mounted the 40-gallon solar heating tank on a platform 7 feet above the shower floor. That elevation produces 3 PSI of water pressure at the showerhead (7 feet ÷ 2.31) — enough for a decent spray but not high-pressure. A pump or additional elevation is needed for a powerful shower.
The tank sits on a plywood platform supported by the 2x6 rails. We wrapped the tank in a black PVC cover (included with the unit) to maximize solar absorption. The polycarbonate roof above the tank lets sunlight through while protecting the tank from rain and debris.
Plumbing: We connected the tank outlet to a 1/2-inch brass ball valve, then a 6-foot length of galvanized pipe down to the showerhead. The ball valve controls flow; we replaced the stock showerhead with a $6 replacement that provides better spray patterns.
Privacy Walls
We used cedar fence boards (6 feet tall, 6 inches wide) nailed horizontally to the 4x4 frame on three sides. The boards overlap by 1 inch, creating a nearly solid wall that still allows air circulation. Cedar is naturally rot-resistant and weathers to a silver-grey over time.
The fourth wall has the door: a timber frame hung on outdoor-rated hinges, lined with the same cedar boards. A simple gate latch keeps it closed during use.
The total effect is a completely enclosed space that is invisible from the road, the neighbors, and most angles from the cabin. This is essential for comfort — an outdoor shower without privacy is not a shower anyone actually uses.
Temperature Performance
We logged water temperature at the showerhead over a full summer. Here are the results:
| Time of Day | Water Temp (°F) | Conditions |
|---|---|---|
| 8:00 AM (fill temp) | 58 | Cold from hose |
| 12:00 PM | 92 | 4 hours sun |
| 3:00 PM | 112 | Peak heating |
| 6:00 PM | 105 | 6 hours sun |
| 8:00 PM | 95 | After sunset |
On sunny days, water temperature peaks at 110-115°F in the late afternoon. We mix with cold water at the valve to reach a comfortable 95-105°F range. On cloudy days, peak temperature reaches only 80-90°F — still usable but less comfortable.
In early summer (June), the tank heats to operating temperature in 4-6 hours. By late July and August, 2-3 hours of sun is enough. The seasonal improvement is due to the sun's angle moving higher and the tank having less thermal mass to heat after the first few weeks.
Two Years of Use: What We Have Learned
- The tank needs a cover in winter. We drain and store the tank indoors from November to April. Freeze damage to the valve and fittings is the main risk.
- A second mixing valve is worth adding. We installed a mixing valve (hot/cold) at the showerhead to adjust temperature without walking back to the tank. This was a $12 upgrade that significantly improved usability.
- Shower frequency drops in cool weather. Below 60°F ambient, the shower becomes less appealing. We use it 4-5 times per week in summer and 1-2 times per week in shoulder seasons.
- No soap in the drainage area. We bring our own biodegradable soap and wash outside the shower area to prevent soap buildup in the drainage gravel.
Upgrades and Variations
If we were building again, we would consider:
- Heavier solar tank: An 80-gallon tank would provide more buffer and hotter water, but the platform would need reinforcement.
- Drain heat exchanger: Running the drain pipe through a heat exchanger could recapture some heat before it goes to the drainage field.
- Enclosed changing area: A small changing bench or shelf just outside the shower improves convenience.
- Hot water from the cabin: Extending a hot water line from our cabin water heater would provide on-demand hot water, but would require a more complex plumbing setup.
More Water System Guides
- Gravity-Fed Water System — our full water supply system
- DIY Solar Water Pumping — pump water without electricity
- Water Filtration Guide — treating water from streams and wells
- Best Water Filters 2026 — our tested recommendations
Was this article helpful?