Cistern – Five Months Later

After five months of operation, the cistern is performing better than expected. And with an above-average rainfall in the "dry" season, there is water to spare.

So it was decided to open it up and look inside.

The first observation was that some roots had grown into the cistern. These hair-thin roots came into the cistern from where the drain field pipe orifice. The design called for the orifice to be closed, but the city demanded that an overflow valve be installed instead. We should have sealed the pipe leading to the overflow valve when installed. Hindsight is 20-20 – so it was done now.

As can be seen from these pictures, the water remains crystal clear thereby disproving one of the many irrational pretexts against cisterns ("has to be cleaned and decontaminated often"). Regardless, the water was tested:

• pH: 8.0
• CLORINE: .5ppm
• Calcium: 1.5ppm
  

It is unclear what causes such a high pH (alkaline) though one can speculate that it is caused by the concrete or from the roots that found their way into the cistern. Now that the roots are eliminated, we'll see.

There is more water than is being used. If one had to do it over again, more Mazzei valves would be installed, say five, thereby increasing the usage from approximately 90 gallons per hour to 450 gallons per hour.

Since there is only one Mazzei valve in this cistern-system, it was decided to drain the cistern to help the lawn and to avoid (just once) the swamp created by the city-demanded overflow valve. An $80 pump was purchased that pumps 350 gallons per hour. After less than four hours, the cistern was nearly drained, and the lawn was very grateful. Based on the pump's power drain, approximately 83 cents of electricity was used.

Since the cistern is being filled more than anticipated (disproving another idiocy "in the dry season the cistern will be empty"), the pump will be used often.

In all, a proven success. Sadly not many have taken advantage of such an inexpensive method to save water (and a few dollars). Perhaps the new and positive management of the city will encourage cisterns.