Clearing Up One of the Biggest Well System Misconceptions
At Griffen Pump Service, one of the most common calls we get in the Hudson Valley is:
"My pressure is low. I think I need a bigger tank."
Let's clear this up once and for all.
Your well pump is what generates pressure in the system. When it turns on, it pushes water into your home and into the pressure tank.
The pressure switch controls when the pump starts and stops. A common residential setting is 40/60 PSI:
If pressure feels weak, the cause is typically:
It is NOT because the tank is too small.
This is where the misconception really falls apart.
It is simply a sealed steel tank with a rubber diaphragm and pre-charged air. If the tank created pressure, what would be generating it? There is nothing inside capable of doing that.
Here is the technical reality.
For a standard 40/60 system, the pressure tank is pre-charged to 2 PSI below cut-in.
So if your cut-in is 40 PSI, the tank is pre-charged to:
That air charge simply allows the system to operate correctly and prevents the diaphragm from collapsing.
If the tank were actually creating pressure, it would need to generate more than 40 PSI. It cannot. The pre-charge is lower than the pump's starting pressure. The pump must turn on to raise pressure above that point.
The tank stores pressure created by the pump. It does not produce it.
The tank's job is to:
When you open a faucet, compressed air pushes water out until pressure drops to 40 PSI. Then the pump turns on and does the real work.
Tank size absolutely matters for proper pump run time, and that depends on pump horsepower.
Every pump — whether ½ HP, ¾ HP, or 1 HP — needs a minimum run time (ideally about one minute or more per cycle).
A larger horsepower pump moves water faster. Without proper tank drawdown, it will rapidly cycle on and off, which is extremely hard on the system.
Tank sizing protects your pump investment. It does not increase PSI.
A quality pressure tank should typically last 10 to 15 years under normal residential conditions.
Signs it may be nearing the end of its life include:
If a failing tank is ignored, it can lead to premature pump failure, which is a much larger repair.
Pressure comes from the pump. The tank has no motor and no way to create PSI. It stores pressure that the pump generates.
If your pressure is not where it should be, do not assume you need a bigger tank. The system needs to be evaluated properly. Pump performance, switch settings, horsepower, and drawdown all have to work together.
At Griffen Pump Service, we focus on correct diagnosis and proper system matching.
No guesswork. No unnecessary equipment.
Serving the Hudson Valley since 1997.
845 897 3107