Rainwater Plumbing: Designing, Building & Owning my House
High above the lake
Our off-grid home
My rain water supply system
It was a beautiful perch high above the edge of a lake. We had views of a distant smoldering volcano and a small island. But that positioned us some 25 meters above the water table. We were living in a developing country with third-world infrastructure. There were no public utilities yet out where we lived.
I had been stationed on a long-term research assignment, so I moved there with my family and built a house that was quite comfortable by local standards. The roof was galvanized sheet metal rather than palm thatch. The walls were homemade concrete bricks rather than split bamboo. The floor was a thin veneer of uneven concrete rather than packed dirt. Electricity was 12 volts like a car or RV and supplied by solar panels.
- My Experience of Living in a Solar Powered House
Click to see how I handled electric power.
Locals obtained water from one or a combination of three sources. There were three dug wells in the village. Some climbed down the steep path behind our house to bathe and wash clothes. Many had a sheet or two of galvanized steel set on angle to fill a 55-gallon drum when it rained. Being Americans, and having one or two small children, we figured that our water consumption would far exceed our neighbors’ usage. I knew more about physics than the plumbing trade, so what I designed and built could best be envisioned as a functional, large-scale science-fair project.
My brick cistern
Cistern I built to store water
I had to have an abundant water supply that was not labor-intensive. Since we lived in a rainforest environment, there was no lack of water—if I could collect and store it. I designed the house in an L-shape, with a water storage “room” notched into the L. This gave it support on two sides from walls of the house. The cistern walls were two bricks thick and the floor was about a meter above ground level. It fed the house by gravity, and all but an outside faucet was at that level.
To prevent algae from growing, I needed to keep out sunlight. So I covered the cistern with flat galvanized steel on a wooden frame. That also reduced the mosquitoes that might breed there. (Since there was still a hole for water to enter, we couldn’t keep them out entirely.) I had always intended to screen the inside wall of the cistern up to the ceiling, but never got around to it. When that troublesome cover eventually rotted and fell in, I simply fished out the pieces and never replaced it. We never noticed much difference in algae or mosquitoes, but a couple of bats came zipping through one evening!
One time I climbed up to check on the level of the water and the general condition of the cistern. This was probably after using it for a couple of years without a cover. I was surprised to see a rat swimming in the cistern! Then I realized he must have been doing it for a very long time and that I was seeing his last breaths. After a quick breath, he would sink out of sight, and then paddle to the surface for another quick breath. I watched him do that about three times, each time staying down longer. “This isn’t good,” I said to myself. So I hastily fetched a dipper and rescued the poor creature. It just lay on the ground, totally spent. Of course, we wondered how many and what kinds of skeletons lay on the bottom! But the water never smelled bad and the health precautions we took seemed to be adequate.
Galvanized steel roof catchment
Gutters and the catchment area
The roof was made of corrugated galvanized sheet metal with about two feet overhang. A reasonable catchment area, thus, drained straight into the cistern, which rose to within a foot of ceiling height. Gutters on the inside lengths of the L-shape extended the catchment area.
Guttering and 55-gallon drum
On the opposite side of the house, at the outside corner of the L-shape, I installed a 55-gallon drum on stilts that connected to the cistern through PVC pipe buried in the floor slab. Gutters along these two longest sides of the roof emptied into the drum. I covered the drum with screen to keep out debris, but I couldn’t prevent algae growth. That proved to be very minor, though, so we only took the barrel down about once a year to clean it out. It was painted white inside so we could more readily check on its condition.
When it rained, water entered the barrel and flowed through the in-slab pipe into the cistern to an equivalent level. In heavy rain, flow through the 2” pipe couldn’t keep up, and the barrel would spill over. The rim of the barrel was positioned a couple of inches below the upper edge of the cistern, so that if everything was completely full, overflow was from the barrel rather than from the cistern directly into an adjacent room of the house. During minor earth tremors, we could hear the water slosh, but it never splashed over the top of the cistern.
When our water supply was running low during a dry spell, the kids and I would climb down to the lake to bathe and swim. Our house helper generally washed our clothes down there as well. This was how the locals lived all the time.
There were exterior spigots at the lowest point of the cistern and near where the pipe from the barrel entered the house. These were primarily for service. They had removable handles since the local people would typically leave water running and I needed to protect my meager supply.
The kitchen sink
Water coming from the barrel first reached the kitchen. The outside of the barrel was painted black to absorb as much of the sun’s rays as possible. This warmed the water in it, albeit slightly. The kitchen sink could obtain the warmest water. None of this water was potable. We had a water filter on the shelf for drinking water. Dishes, fruits and vegetables were all rinsed in a solution containing a disinfectant.
Cistern water entered the house through a pipe that was about hip-height. The pipe entrance was about two inches above the cistern’s floor to avoid silt, and was covered with a coarse screen to prevent any larger debris from entering and clogging up the works.
Immediately next to the cistern was a small bathing room. A spigot was there to fill a far smaller “tub” holding about 15–20 gallons. This was lined—as was the entire room up to about five or six feet—with bath tile. The custom in that part of Asia was to bathe by splashing water over oneself with a dipper rather than climbing into the tub. We could actually get a bit of warm water if we shut off flow from the main cistern and filled the tub just from the hot barrel in the late afternoon.
Adjacent to the bathing room—with an adjoining sliding door—was the toilet room. We had a typical Western toilet, but adjusted it to use the least amount of water necessary. House rules permitted flushing for solids and otherwise only when necessary. Typically, a dipper of water grabbed from the tub next door was sufficient the rest of the time.
The septic tank and waste water
I really didn’t have a clue what a septic tank was back then—and this was before the days of the internet for research purposes. Fortunately, at least one local person understood the principles, and what he built served the purpose. He dug a pit, lined it with bricks, and inserted a brick divider. Solids flowed first into one side, then as effluent into the next, which had a short vent stack. I don’t recall any leach field.
The bathing room had a floor drain that emptied straight through the foundation at grade. It should have had more slope to prevent buildup of hair and soap scum. I had to get out there and poke at it with a wire periodically.
The kitchen sink drained into a tiny pit filled with gravel and covered with sod. The main thing I was concerned about there was not drawing flies to grease and whatever else might be in dishwater. That was more than adequate since we were conserving water.
Plumbing articles by the author
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Lower water consumption and water heating bills. Conserve water and natural resources while saving on energy. Install environment-friendly 1.5-2.0 gpm low-flow shower heads, a plumbing DIY project.
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Test your plumbing vocabulary with this toilet-shaped crossword puzzle containing 58 words. It includes clues and the solution.
What I’d do differently next time
The biggest thing I’d change if I could do it over is to increase the size of the pipe between the drum and the cistern. For such a low-pressure system, 2” simply does not provide enough flow during anything heavier than a light rain shower. A full 4” PVC pipe would have added very little to the cost of materials and would have enabled us to accumulate more quickly during the heavier rainstorms.
I would also have installed a cleanout where the pipe entered the floor slab. At the time, I don’t think I knew such a thing existed, but recognized the need for it and had tried to make a service link with a section of hose and a couple of hose clamps!
I would do something to try to raise the water pressure and temperature a bit. At one point, I bought a small 12-volt water pump, intending to pump water to a small holding tank at the highest point of the “attic.” That would also raise the water temperature significantly because it would be right under the galvanized iron roofing. Of course, I would have had to rig a float valve and all the plumbing, so I never got around to it.
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