The camping scene at our “tiny house” has worked well over the past few years. Small at about 16×9 feet, but comfy with a wood stove and 12 volt solar lighting. We put in a gravity feed water system using a 5-gallon jug in the loft, but got tired of hauling water from town for every visit. Instead, why not haul H2O just a couple times a year and fill a big tank on our property, which could then be used like a spring, or even hooked up with a hose during non-freeze months? With a big enough tank we would have more water than we’d ever need just a few steps away.
We engineered a solution by acquiring a couple of above-grade pickup truck water tanks. (Cheap used tanks are available, but for drinking water you have to buy new ones since you have no way of knowing what’s been in a used tank). We enclosed the 400 gallon tank in an insulated stick-framed box. The tank is set a few feet into the ground to discourage freezing and allow the cover box to be shorter in height. Since the tank enclosure box needed a roof, we built a tool shed on top. While engineered for extreme snow loads and depth, everything was done small and portable so as not to create problems with building codes.
For a water tap, we buried about 10 feet of flexible hose a few feet below grade and daylighted that down the hillside from the tank via a freeze proof hose-bib faucet like you’d use on the outside of a house. During winter, a tarp and a few logs create a snow cave where we access the faucet and fill water containers. (Next summer we’ll probably hook the tank directly to the tiny house for water on demand, using a drinking-grade water hose like you’d hook up in an RV park.)
Filling the tank is done once or twice a year using another 200 gallon truck tank, as shown in photo above. If I ever wondered why we own a truckosaurus, those ponderings have been put to rest. Water is heavy and our two-track vehicle access is steep.
Once a year we “flash” treat the permanent tank using bleach. More, for biological safety we filter or boil any water we drink out of the permanent tank — though the H20 remains clear, cold and clean since we source heavily chlorinated residential water drawn from our house in town.
One lesson learned: the caps on these tanks have an air vent that small insects such as ants can climb through. Install screen mesh over or under the cap to prevent interesting little floaters from appearing in your water supply. To clean debris out of the source tank, mount a fine screen dipper on a stick like the tool you use to clean stuff out of swimming pools.
Once winter weather begins we lay a few slabs of rigid “blue foam” insulation over the ground where we buried the hose tap. It froze for a few days last winter during an extreme cold snap (20 below zero F), but otherwise stayed usable due to ground warmth keeping the freeze at bay. The water in the tank never freezes due to it being on the ground in an insulated box. We cover the hose bib with a small foam cover sold for that purpose, and blanket the whole assembly with an old synthetic sleeping bag when not in use.
Ventilating the insulated tank “house” is a challenge. Too much air flow and the water tank will freeze. Too little venting and humidity builds up to the point of damaging the covering structure and encouraging mold. Last winter we had a bit too much humidity. Improved solution is a vent in the door and a riser on the opposite end of the cover box made from 4-inch black plumbing pipe that warms in the sun, thus encouraging air flow. I’ll monitor temperatures this winter and restrict air flow if it looks like we’re risking a freeze.