5. What is “active storage” and why is it important to the community?

The water that is “stored” in the tank is like the savings in a bank account.  It is there for the times that current demand exceeds current pumping capacity and when needed for firefighting purposes.  When there is no storage capacity (e.g., savings), pumps have to work nonstop to provide water into the tanks as fast as demand draws it out.   Further, the volume of water needed to fight a fire, on top of daily water usage, is significant and can only come from storage.  When a fire occurs on a day of peak demand, when water users are drawing water out as fast as it is pumped into the tanks, water to fight the fire must come from water stored in the tank.  The requirement that water for firefighting come from water stored in the tank is a standard condition of water engineering, in addition to being required by the State and the Insurance Services Office that sets the Town’s insurance rates.

 If water in the tanks is flowing out faster than it is pumped in, the level of water in the tanks will drop.   During the drought of 2016, there were only 30 inches of water left in the bottom of the Paines Hill tank.  This would not have been enough to fight a fire if one had occurred in that moment.  We were lucky to avoid a disaster.  It was our wake-up call to address the system’s deficiency.

 The storage capacity of the tank is directly related to the height of the water tank and the height of the buildings that it serves.  If buildings are located as high as, or higher than the tank, the water level in the tank must remain as high as possible to maintain the proper pressure.  

 In technical terms, the lack of active storage in the system is directly related to the maximum serviceable grade line (or elevation) at which the system can provide customers with a reliable minimum pressure. As discussed in detail in Section 5 of the Plan, Weston has a significant deficit of active storage, or usable water volume, beyond daily needs. The active storage is based on the operational range of the tank and the service elevations of the system’s customers; it is not the same as the total volume of water in the tank. Under current conditions, in order to maintain service to higher elevations, the pumps run continuously during times of high demand to keep the tanks as full as possible.

 Water tank height is what provides water pressure.  More height is needed to serve customers close to the tanks, who currently have inadequate pressure.


Show All Answers

1. 1. What is the Water Master Plan and what was it designed to do? Should it be updated?
2. 2. Are our water tanks about to fail?
3. 3. What are the priorities that Weston has established to deal with water system infrastructure investment?
4. 4. Can we address the deficiencies of our water system by encouraging Townspeople to conserve water?
5. 5. What is “active storage” and why is it important to the community?
6. 6. What is the condition and expected life of our distribution system? How is the Town budgeting for water pipe replacement?
7. 7. Can we solve our water provision issues using more pumps or using the pumps we have more continuously?
8. 8. What other steps should Weston take to improve its water system?
9. 9. Why should we replace all three of Weston’s water tanks? Do we need three tanks, or could we make two tanks work?