Pressure in a well water supply system is primarily maintained by a well pressure tank that uses compressed air to pressurize the water. Since wells themselves generally don't provide constant pressure, the well pressure tank system acts as both a water storage and a pressure regulator.
Here's a breakdown of how it works:
Key Components
The well water supply system consists of several key components working in concert:
- Well Pump: Submersible or jet pump that draws water from the well.
- Pressure Tank: A storage tank, typically steel or fiberglass, designed to hold water under pressure. This is the core of the pressure maintenance.
- Pressure Switch: Monitors the water pressure in the tank and activates the well pump when the pressure drops below a set level (e.g., 40 PSI) and deactivates it when the pressure reaches a set level (e.g., 60 PSI).
- Check Valve: Prevents water from flowing back into the well.
- Piping: Carries water from the well to the tank and then to the house.
The Process of Pressure Maintenance
- Pumping Water: The well pump draws water from the well and pumps it into the pressure tank.
- Air Compression: As water enters the tank, it compresses the air inside (either in a dedicated air chamber or within the tank using a diaphragm or bladder). This compression is what builds pressure.
- Pressure Buildup: The pressure builds as more water is pumped in, compressing the air further.
- Pressure Switch Activation: When the pressure reaches the upper limit set on the pressure switch (e.g., 60 PSI), the switch shuts off the well pump.
- Water Supply: When a faucet is opened in the house, the pressurized water in the tank is forced out and into the plumbing system, providing water under pressure.
- Pressure Drop: As water is used, the pressure in the tank gradually decreases.
- Pump Reactivation: When the pressure drops to the lower limit set on the pressure switch (e.g., 40 PSI), the switch turns the well pump back on, and the cycle repeats.
Types of Pressure Tanks
- Conventional (Air-Over-Water) Tanks: These tanks have a simple design where air directly contacts the water. They require occasional air recharging, as the air can dissolve into the water over time, leading to waterlogging.
- Diaphragm Tanks: These tanks use a rubber or butyl diaphragm to separate the air and water. This prevents the air from dissolving into the water and reduces the need for air recharging.
- Bladder Tanks: Similar to diaphragm tanks, bladder tanks use a bladder to separate air and water. The bladder contains the water, preventing contact with the tank walls, which can reduce corrosion.
Example Scenario
Imagine you turn on a faucet. Water flows from your tap because the water in the pressure tank is pressurized. As water leaves the tank, the pressure drops. When it reaches, say, 40 PSI, the pressure switch detects this drop and signals the well pump to turn on. The pump refills the tank, compressing the air until the pressure reaches 60 PSI. At that point, the pressure switch turns the pump off, and you have a tank full of pressurized water ready for use.
