What Happens if the Tank on Your Well Has Low Pressure?

Well Tank

• The tank that's connected to a well's pump and the home's water pipes serves two functions. It stores water for use as needed and puts pressure on the water within the home's plumbing. Inside the tank is a bladder filled with air. As the well pump fills the tank with water, the water compresses the bladder and the air inside it, which results in increased air pressure in the bladder. The air pressure inside the bladder exerts pressure on the water inside the tank and the water supply plumbing.

Pressure Switch

• The pressure switch senses the amount of pressure inside the well tank. When the water pressure falls below the cut-in setting, the switch turns the well pump on, which adds water to the tank. The water pressure increases until the cut-out level is reached and the switch turns the pump off. The switch controls the minimum and maximum pressure inside the tank.

Low Tank Pressure

• The air pressure in the well tank's bladder must overcome the force of gravity to move water through the pipes to the home's plumbing fixtures. The higher the water must travel, the higher the pressure required to move it. As the water in the home travels upward, the pressure drops. When the weight of the water equals the pressure inside the well tank, it ceases to flow because the force of gravity prevents the water from traveling farther. Low tank pressure means low or nonexistent water pressure at fixtures. If the amount of air in the bladder is so low that the tank pressure never reaches the cut-off setting of the pressure switch, the switch won't shut the pump off and the pump runs continuously or rapidly cycles on and off, which shortens the pump's life.

Low Pressure Causes

• Low tank pressure has two causes. A pressure switch setup with low cut-in and cut-out settings won't allow the tank to fill with enough water, which results in low water pressure in the home. The air bladder within the tank might not have enough air in it to provide the pressure required to push the water through the water supply pipes in the home.

Tank Pressure Solutions

• Most tanks have a connection nipple that attaches to an air hose. The amount of air inside the tank is adjusted to provide the necessary pressure. Some tanks might not carry pressure ratings suitable for all homes and a new tank is required.
  The pressure switch has two adjustment nuts. One nut raises or lowers the cut-in pressure and the second nut adjusts the range. As the cut-in pressure is increased, the cut-out pressure also increases. Always check the tank's maximum pressure rating before trying any adjustment of the pressure switch or air bladder.