Hot and cold water Water is stored in a 290 gallon roof tank or cistern which is filled by water pumped from the 2,000 gallon water storage tanks. These tanks are periodically replenished by a large water truck from San Felipe. The water from the roof tank is fed by gravity to: 1. A sill cock at the Southwest corner of the building; 2. The toilet; 3. The DC water pump. Cold water from the DC pump feeds directly to the bathroom sink, shower and kitchen sink, and to the water heater. Hot water from the water heater goes to the shower and the two sinks.
Roof tank pump connection
From 2,000 gallon water storage
[above] Schematic of the Cube's water system. Gravity feed water: light blue; pressurized water: dark blue; hot water: red
The 2,000 gallon long-term water storage system makes it possible to stay at the Cube for several weeks without having to obtain water from local wells.
Drains and vents Drainage from the toilet goes by way of a 4 inch ABS pipe system which exits the building on the South side and is carried via buried pipe to the septic tank at the base of the dune about 200 feet from the building. The septic tank is a simple concrete-lined container with an air vent. There is no output or drain field. The slurry decomposes within the container. Over the course of ten years there has been no sign of the septic tank filling up. Water draining from the shower, the bathroom sink, and the kitchen sink is channeled into a 2 inch pipe and drains to the yard. Each separate run of drain pipe is connected to a 1 inch vertical air vent—usually at the first elbow connection. These vents emerge at the rooftop and are surrounded by flashing. When walking on the of stay clear of the vents to avoid fumes.
Plumbing the Cube Once the walls were framed, the bathroom floor was tiled, and the fiberglass shower enclosure installed it was time to fit and connect the drain pipes and vents. My big mistake was to use PVC glue for the black ABS drain pipes. I had to tear everything apart and start again! Nevertheless, I found the drainage system relatively easy to construct and was able to complete the work within two weeks, relying on information in a book I had bought with the priceless title of Creative Plumbing.
As soon as the roof tank was installed I laid a system of PVC pipes carrying gravity fed water from the tank to the toilet and to a DC water pump mounted up in the ceiling. Water from the pump under pressure needed to go in 1/4' copper pipes that would have to be soldered together. This was a lot more difficult to manage than the plastic piping and the system was more complex. The original idea was to have a passive solar hot water system made from a coiled plastic pipes mounted on the rooftop, but I was persuaded by a neighbor who is a retired plumber to install a small, inexpensive propane hot water heater instead. (This water heater would break down within three years, was replaced with a similar one which also succumbed to corrosion three years later. The current heater is the third one to be installed!)
In an effort to keep the pressure water system exposed and accessible should anything go wrong, the hot and cold water pipes travel for most of their distance alongside the ceiling joists and are clearly visible. Many of the pipes converge inside the wall dividing the bathroom sink and the shower. While the framed walls still open, the day of reckoning would come when all the copper pipes were in place and the water pump was switched on to test the system under pressure. Alas, I discovered that I had inadvertently created a sprinkler system as water spurted from incorrectly soldered joints at several points in the ceiling. Fortunately neighbor Lee and a friend were at hand with a blow torch and some solder and graciously fixed the leaky welds.
[left] Working drawings of the Cube's drains and vents. Drainage to septic tank: brown; drainage to grey-water: grey; vents: green