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.

Supplies:

  • 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

Instructions:

  1. 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].
  2. Situate the solar collector facing south, with full exposure to the sun between 10 a.m. and 2 p.m. [source: Herman].
  3. Replace the plug at the bottom of the tub with the male adaptor. Attach the copper pipe to the adaptor [source: Herman].
  4. 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].
  5. Route the pipe vertically from the solar collector, then horizontally to the tub.
  6. Install a gate on the "hot" and "cold" pipes, to control the water flow.
  7. Install a safety valve in the "hot" pipe.
  8. Install a drain valve at the low point of the system.
  9. Install threaded unions in the pipes, near the tub.
  10. Test the plumbing, to make sure it doesn't leak.
  11. 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.
  12. 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.
  13. Cut a lid for the hot tub from scrap wood, and install it with hinges.
  14. Insulate all the exposed pipes with the foam insulation [source: Herman].
  15. Fill the tub with water to within 8 inches (20 centimeters) of the top.