HERE ON THE BIG ISLAND – Getting Into Hot Water

By Kelly Moran

Could You Live Off-the-Grid?  Part V – Getting Into Hot Water

          You probably don’t want to live anywhere without hot water.  But fortunately, that’s the easiest convenience to have, off-the grid.  In our warm and sunny climate (sunny enough, even in Hilo), a simple black plastic water-bag on the roof will give you hot showers from afternoon through early evening.

          Utility executives know this.  They also know that heating water with electricity is terribly wasteful and inefficient; and that they may never get approval to build another power-plant here if they don’t help to hold down demand.  So the Hawaii Electric Light Co. (HELCO) is offering households huge incentives to replace electric water heaters with solar water-heaters.

          You can’t go wrong with solar.  Ideally, you should have a broad southern exposure, but almost any place with open sky views should be sufficient to generate heat from the sun.  You will, however, need a tank, and some backup heat source (propane or electricity) to keep the tank’s temperature constant.

          For an attractive alternative, consider an “on-demand” water heater, in which a small propane burner fires up only when you open a hot-water tap.  There’s no tank (a cost-saving in itself), and though the heater may have a pilot-light, it isn’t burning a lot of gas to maintain a high temperature when you aren’t using hot water.  These systems are very inexpensive, and easily installed by any plumber.  Just be sure the burner is vented, for safety, to the outdoors.


          You could also combine a solar water-heater with a slightly more costly version of the on-demand heater, which has a temperature-sensor built in.  It can then raise up to full hot-water temperature the water that’s already warm from the sun.

          Those solutions are excellent for showers and small tub baths.  As for a resort-size, Jacuzzi-type hot tub, big enough for two or more people, you will need sufficient electricity to run the “jets.”  But a more important consideration is that heating such a large volume of water takes a lot of energy – quite likely more than can be heated by the sun in single a day.  But there are other ways to heat a big tub of water, especially if you’d like your hot-tub experience to be naturalistic.

          In old plantation days, a Japanese farm worker would build a bathhouse, separate from his home, with a wood-fired furo inside.  He’d lay a brick-and-mortar firepit and chimney, set a sheet of copper over the firepit, and make a tub out of redwood (and a redwood grille, to keep from sitting down on the hot metal).  An hour or so after starting the fire, the tub water would be hot enough to soak in.  Traditional bathhouses have drains in the floor, because the Japanese always wash and rinse themselves off first, and only then get into the tub.

          Many years ago, I lived in a house near Hilo that had exactly that sort of backyard bathhouse with a brick-firebox and copper-sheet furo.  I would jokingly compare the experience to the cartoon image of missionaries being cooked in a cannibal’s cauldron.

    Fortunately, there is a modern alternative.  It’s called a “snorkel stove” ( – an aluminum firebox that sits in one part of the tub, separated from the bathers, for safety, by a wooden screen.  Since it takes up about one-person’s-worth of space, the tub has to be slightly bigger than you might otherwise need.


          Having a separate bathhouse makes the experience seem special, somehow; and since the tub isn’t in your regular bathroom, it’s more relaxing and more attractive, especially if you share the tub with family or guests.  You’ll probably want to site the bathhouse close to your home, though, and in rainy places, link the two structures with a covered walkway.

View Other Posts in the “Could You Live Off-the-Grid?” Series