One of the primary functions of Nacho’s water system is obviously to deliver drinking water to our sink. Dealing with bottled water is a pain, and almost nobody likes Giardia. Here’s a rundown of how the system works.
The tanks are filled from the outside of the van; there is a separate fill for the hot and the cold tanks, and each holds 15 gallons. We usually add a cap of bleach to each tank. Even though the sanitation system will take care of any contamination, we prefer the belt and suspenders method, and it keeps the tanks clean.
The water system has a UV light and some other electric components. We don’t want these to be powered on all the time, so there is a master water system power switch near the sink. When the switch is off, a magnetic solenoid valve also closes and power is cut to both pumps, keeping water from flowing through the circuit for any reason.
When water is requested at the sink, it goes through a series of steps. Obviously, it starts in the tanks. Next, the water goes under the floor to the pump, which is located in the floor tub. There is a separate pump for the hot and the cold water.
The pump fills up an accumulator tank. This is basically a pressurized cylinder with a bladder in it. It dispenses water from its outlet at a constant pressure. There is an accumulator for each water tank.
After the accumulators, the hot and cold water streams join before going through the UV light tube. The UV light will kill anything that was alive in the water, such as bacteria and viruses, by breaking down its DNA.
After passing through the UV light, the water goes through the filter. We chose a 0.2 micron filter, which is over 10 times finer than a standard home water filter. This filter will remove heavy metals, flavors (including the bleach), spores, and dead things killed by the UV.
The water then goes through a couple of check valves to prevent backflow, and then arrives at the sink. Anything dumped in the sink gets recycled into a catchment system where it is converted through alchemy into solid gold bars, which we sell as we go to fund our trip.
You know that feeling you get when you drink a nice tall frosty glass of water, only to realize after the fact that the water was infested with terrible man-eating bacteria? Yeah, me too. Fortunately we designed a feature into the water sanitation system to avoid this awful fate.
If the filter gets full, it will stop the flow. This is obvious. The UV light does, however, require a more sophisticated safety mechanism. There is a magnetic solenoid valve just upstream of the UV light (same one that’s controlled by the master power switch). The valve is normally closed, meaning that if no electricity flows to it, it closes the water pathway. When current is applied to it, the valve opens. I wired the solenoid in series with the UV light. This way current flows from the battery (-) terminal, through the UV light, through the solenoid, and then back to the battery (+) terminal. If the UV light burns out, current can no longer flow through the circuit, and thus power is cut to the solenoid, closing off the water flow immediately. In the end, no water will ever reach the sink unless it has gone through the filter and a functioning UV light.
Giardia: 0, Brad & Sheena: 1.
We tested out the water system on a trip that we took in May to Mexico’s Baja peninsula. It’s well known that accidental ingestion of Mexican water is the cause of intestinal mayhem for so many gringo travelers. With Nacho’s water system we were able to put Mexican water directly into the tanks and drink it safely from the tap. One less thing to worry about! Following that trip I wrote three blog posts about our adventures for Southwest Windpower, as we were also testing out their Air Breeze wind turbine on the trip. You can read the blog entries here: