Central Water Tank
Central Water Tank supplies irrigation water to the Central Greenbelt area, plus some areas to the east and west. It is made of thick redwood planks, held together by metal banding. All irrigation water for the Central Greenbelt area comes from this Water Tank.
The tank is filled with a combination of water from an underground well, that goes down about 200 feet, and from Water District water, which is potable water, similar to that supplied to Crossings’ homes. The level of water in the tank is measured by the vertical scale on the tank, which shows a maximum of 15 feet. A computer system controls when Water District water needs to be pulled into the tank. Water from the well is pumped into to tank at all times, unless the tank is filled.
Water is released for irrigation during most evenings, when irrigation timers call for water. The demand for water is much greater than the volume of water that can be supplied by the underground pump; thus, Water District water must be pulled into the tank, during the night, to supplement water being released from the tank. A booster pump ensures proper water pressure for the irrigation system.
There have been debates from when the tank system was first installed as to whether this water tank system pays for itself. In fact, the water pumped from underground only supplies about 20 percent of the total irrigation water demanded in the Central Greenbelt. The general consensus is that the costs of the pumping system more than offset the cost of Water District water that we would, otherwise, have to pay for.
Leaking/Weeping Water Tank?
At times, the tank may not be fully filled. As such, the redwood boards near the top dry up a bit. Then, when the tank is filled, the top of the tank will “weep” in ways that make it appear like the tank is leaking. In fact, the redwood boards are expanding and sealing. The temporary loss of water during this process is a byproduct of redwood water tanks and the only alternative to this would be replacing the entire tank with a metal or aluminum equivalent.