The water cistern is here!
But now it's time to think about our water source. Public water lines pass through our farm. In fact, we ran 3000 feet of pipe, at considerable expense to us, in order to hook up our mobile home to public water. The endless supply of reliable clean water is great, but frankly because of the chlorinated smell and white powdery sediment, the public water is less than ideal for drinking or washing dishes (and the sediment wreaks havoc on hot water tanks and coffee makers). We're resolved to collecting and purifying our own water at the new house.
In designing our water supply, the first thing that struck me was how crazy it would be to flush our poop with sparkling drinking water. Because public utilities currently run only one set of water lines, they deliver water that's really too nice to flush poop and not really nice enough to drink. We're not under the same constraints, so our house will have a dual water supply. We're going to catch rainwater from our slate roof, store it in an underground cistern, and use it to wash clothes, flush toilets, and water plants. The water would probably be drinkable in an emergency, but we're not going to go through the extra effort and expense to hyper-purify this water. (Our drinking and bathing water will come from a well and will pass through several stages of purification... but more on that later.)
Using my backhoe, our neighbor dug a nice square level hole and lined the bottom with sand the day before our concrete cistern arrived. The delivery truck arrived the following day and the driver used the on-board boom-lift to place the 1200 gallon cistern gently in the ground. (cost was about $600 including delivery) Today, our neighbor's son is going to crawl into the dry cistern and parge the inside with Thoroseal to keep water from leaching out (and contaminants from leaching into) the concrete tank. The directions on the bag of Thoroseal say to mix the contents with water and Acryl 60, an acrylic modifier, but I've decided to go "off label" and omit the Acryl 60. The inside of the tank is very clean and I doubt we need the Acryl 60 (manufactured by BASF) to help with bonding or with strength. The local masonry supply house says this is OK - that 15 years ago, Thoroseal directions mentioned Acryl 60 only as an option for special circumstances, not as a requirement. Primarily, I don't want another chemical in the tank in contact with our water supply. And finally, the Acryl 60 has a strong odor of fumes that may not be healthy for the boy who is going into the tank to coat it. (btw, I've read horror stories of folks applying epoxy type coatings in tanks... someone passes out in the tank, and would be rescuers succumb to the fumes as well. A tragedy best avoided by reading labels and providing adequate ventilation!!! Thoroseal is a masonry product that seems to have virtually no fumes.)
The next step in our rain water catchment project will be to add gutters to the back of the house and plumb them to the cistern. I've seen plans for automated (and manual) setups that allow you to "waste" the first few gallons of water from the roof during a rainstorm so that recent bird-poop, soot, leaves, and what not does not flow into your water catchment. Sounds like a good idea to me. A rain shower which produces 1 inch of rain on 1000 square feet of roof should yield about 500 gallons of water. I think we use about 50 gallons of water a day for flushing and clothes washing, so each good storm should give us about 10 days of wash/flush water, and the cistern will hold a 24 day supply. Of course, we can always fill the cistern with the well water... if we can develop a good well somewhere near the house.