How Your Well Works
Part IV - Storage Tank Systems
Due to the nature of wells, water isn't always available in the quantities we'd like to use, especially in hot dry summer months. In this situation, a storage tank system can be ideal.
In a typical storage tank scenario, the well pump supplies water to fill the tank. Because the volume of the tank is larger than the amount of water the well is capable of producing at once, the well pump is outfitted with a protection device called a no-load sensor. The sensor monitors the electrical current draw from the pump for any sudden drops which indicate that the water level in the well has fallen below the suction end of the pump. Because the pump and motor are cooled by moving water, they would be permanently damaged if they continued to run. The load sensor prevents this by opening a relay in the pump control box, shutting off power to the pump and stopping it.
Activation and deactivation of the well pump is typically controlled through the use of float switches. Typically two float switches are used, one near the top of the tank breaks the electrical connection to the pump when the water level gets too high. Another placed towards the bottom of the tank closes to create a connection to the pump when the water level drops down too low. Together these switches keep the tank filled and also prevent the well pump from turning on too often.
As for the tank pump, most any type of pump can be used depending upon the application. For fire suppression, high volume centrifugal pumps which are simply multi-staged jet pumps are usually used. For typical residential applications, the choice of pump depends entirely upon preference. Many tank systems simply use a jet pump connected to the output line of the tank. For larger or long distance applications, in-tank submersible pumps such as the one pictured are typically used. When used inside the tank in this fashion, the pump is laid horizontally rather than vertically and is placed as close to the bottom of the tank as possible to ensure that all the water can be removed. To help cool the pump, a pump installer will typically place some kind of shroud over the pump.
These systems can provide a reliable source of potable water for low-yielding wells and also a high volume water source for demanding applications such as fire suppression and irrigation.