I once bought a postcard of a black and white photo of a "cowboy" hot tub-two guys soaking in one of those oblong stock watering tanks. I thought, why couldn't this be made into something more luxurious? I knew there were round tanks, and my local farm supplier had one slightly less that five feet in width made of galvanized steel for about $150.

I have a deck that is not close to any source of hot water and it occurred to me that I could heat this tank like a giant pot with a three burner propane camping "stove" I bought for about $60. (This was heavy duty, with legs and large burners-see photo.) The original configuration had me setting the tank on four 8" x 8" x 6" concrete blocks, allowing room in between to slide the burners underneath as needed to heat the tank. I also added some sheet metal under the burners just to make sure there was no way heat/fire could be transferred to my floor board.

A cattle watering tank makes a great hot tub.

I initially put about a foot and a half of water in the tank and tried heating it up-it took about two hours for 60 degree water to get to 90-100 degrees with two burners blasting, somewhat less with three burners. This was certainly a limitation-it's no instant hot tub, but if you have the time to heat it, it will stay hot all night with the solar blanket I now put on the surface of the water (along with the redwood insulation I later added). Of course, heating time will depend on the ambient temperature of the water, which varies depending on the weather and location.

My wife didn't really like the tub much because of the metallic look and feel, so I was determined to improve it. For one thing, it drained very slowly out a too small 3/8" hole. It took me some time to come up with a flexible rubber tube from the hardware store that could be placed inside that hole, which would actually siphon the water out much faster for regular cleaning. (Use rubber plugs on each end.)

I bought 1/2" x 6" redwood planks which I attached together around the inside of the tank with those metallic brads sealed with plumber's "goop" since they sometimes stuck out a little. I also painted the outside of the tank green and added a "dangling" frog. Lookin' better!

A later modification was putting the three burner stove on a three inch high board with roller wheels so I could slide it out from under the tank easier when I wanted to use it for other purposes, such as on-deck cooking! I also added a 1/2" thick black rubber mat that is used in restaurant kitchens to keep workers from slipping on greasy floors (available at Home Depot).

What I didn't figure on is that the redwood would "bleed" like it did. After the water sat a couple of days, the water had discolored so much that you couldn't see to the bottom. Plus, there was an odor.

I thought the stain would go away after a while but even after draining the tank I was still getting severe discoloration. That wouldn't do, especially since I didn't want to drain and clean the tank every time we used it.

I finally solved the bleeding problem by putting a 16" high strip of wood-looking vinyl all around the base of the tub, anchoring it to the redwood, and sealing it with "goop." Just make sure that the goop dries well and that there are no pinholes allowing water to seep from the tub under the vinyl and into the wood.

At one point I was given a device that sets on the edge of bathtubs to create a bubbling action. This is not part of the original $300 (I got it free), but you might look into something like this so your hot tub is not just a tranquil "lake." Another approach might be to get one of those little immersible fountain pumps to run a stream of water from the tub into the air for a dripping/squirting effect.

A nice touch is having a shelf attached to or next to the tub on which you could place candles, bath salts, etc.

Supply list:

5' round stock watering tank (about $150)
Three burner camp stove (heavy duty, wide burners, about $65)
12 - 1/2" x 6" redwood planks, cut to size
Solar cover (www.poolsupplies.com)
Rubber hose for drain
4 - 6" x 6" x 8" blocks
Propane tank
Enamel paint
Plumber's goop
Rubber mat
Wood-grain vinyl

Optional:

Frog decoration
Immersible fountain pump
Small ladder to access hot tub