Building a hot tub takes some skill, but shouldn't be too hard for an avid do-it-yourself enthusiast. Here's an overview of how to build a one-person hot tub.
- 100-gallon (379-liter) Rubbermaid Agricultural Products poly stock tank [source: Kossow]
- 4-foot-by-10-foot (1.22-by-3.05-meter) solar collector, with pipes, valves and fittings
- Hardwood pallet and ¾-inch plywood
- ¾-inch copper pipe
- Carpentry tools
- 1 ½- to ¾-inch male adaptor
- 1 ¼- to ¾-inch bushing
- Silicone caulking, 1 ¼-inch flare nut
- Two gate valves
- Pressure-relief valve
- Drain valve
- Threaded unions for the pipes
- Fiberglas batting, 4-millimeter poly sheeting
- Vertical battens cut from 2-by-4s
- Galvanized steel flashing
- Scrap wood, hinges
- Standard foam insulation
- Find a level site outdoors for your hot tub. The bottom of the tank must be 1 to 2 feet (30 to 60 centimeters) higher than the top of the solar collector [source: Herman].
- Situate the solar collector facing south, with full exposure to the sun between 10 a.m. and 2 p.m. [source: Herman].
- Replace the plug at the bottom of the tub with the male adaptor. Attach the copper pipe to the adaptor [source: Herman].
- Attach the hot-water pipe at a height equal to 2/3 the minimum filled water depth of the tub. Cut a hole in the tank, low enough to be submerged when filled. Secure the bushing with a flare nut. Caulk the inside of the tub [source: Herman].
- Route the pipe vertically from the solar collector, then horizontally to the tub.
- Install a gate on the "hot" and "cold" pipes, to control the water flow.
- Install a safety valve in the "hot" pipe.
- Install a drain valve at the low point of the system.
- Install threaded unions in the pipes, near the tub.
- Test the plumbing, to make sure it doesn't leak.
- Build a box around the tub, using 2-by-4s. Insulate the inside of the box with fiberglass batting. Wrap the box with poly sheeting.
- Put vertical battens on the sides of the tank. Cover them with pieces of galvanized steel flashing. Waterproof the pieces where they overlap, using silicone caulking. Cover the flashing with 2-by-4s.
- Cut a lid for the hot tub from scrap wood, and install it with hinges.
- Insulate all the exposed pipes with the foam insulation [source: Herman].
- Fill the tub with water to within 8 inches (20 centimeters) of the top.