Home » Well Water Pressure Tank | Everything you need to know

Well Water Pressure Tank | Everything you need to know

Updated on June 15, 2022

A pressure tank in your well water system is a critical component. It is important to understand its purpose and how it works so you can troubleshoot it yourself when any problem comes.

There are three basic purposes of a well water pressure tank. It stores water, provides water when the pressure pump is not running and maintains a constant water supply during high demand.

In this article, we will discuss all the major aspects of a well water pressure tank.

  • Well water pressure tank PSI
  • Well water pressure tank installation
  • How does a well water pressure tank work?
  • How to drain a well water pressure tank
  • What size well water pressure tank do I need?
  • How to tell if your well water pressure tank is bad?
  • How to fill a well water pressure tank?

Let’s begin our discussion!

Well Water Pressure Tank PSI

Maintaining proper pressure in your well water tank is critical to ensure its proper functioning. Each pressure tank has a pressure switch that controls the cut-on and cut-off pressure for the pressure tank. In other words, it tells the pump to turn on and off.

For example, if the pressure setting on your switch is 40/60. 40 is the cut-on pressure, and 60 is the cut-off pressure. When the pressure in the system drops to the low preset setting (cut-on), the pump turns on, and when the pressure in the system rises to the high preset setting (cut-off), the pump turns off.

The Right Pressure Settings: The common pressure settings on well water tanks are 20/40, 30/50, and 40/60. The right pressure setting depends on your home size, usage pattern, the number of stories in your home, and how far your faucets are from the pressure tank.

Can I change the pressure settings on a well water tank?

Yes. You can change the pressure settings on a well water tank. It is an easy but slightly complex process. All the required information is available in the user manual of your well pump as well.

The following video explains how you can adjust the pressure settings on a well water pressure tank.

Well Water Pressure Tank Installation

Many states in the U.S. mandate that certified professionals must perform all well water installation and maintenance tasks. However, some neighborhoods permit well owners to perform maintenance tasks such as replacing a well water pressure tank. Moreover, it is well owner’s responsibility to check and maintain water quality.

Buy a new tank of the same size and, if possible, get the same brand, so you can hook up everything in the same way. You may need to alter the installation space for a bigger tank.

Let’s learn how you can replace a well water pressure tank.

  • Begin by turning off the circuit breaker to the well and the wall switch near the pressure tank.
  • Drain the water in the pressure tank by connecting a garden hose to the draining valve on the pressure tank.
  • You can also open the faucets nearby to speed up the draining process.
  • You need to install a plumbing Tee depending on the tank’s specification.
  • Install Teflon tape on both ends of the tap fittings; install the drain valve, the pressure relief valve, and the pressure gauge.
  • The tank assembly will look like the one shown in the image below.

The tank assembly will look like the one shown in the image below.

  • Install connectors on both ends of the Tee (one going to your home and one accepting water from the well).
  • Check the air pressure in the water tank. Refer to the user manual to see the cut-on pressure of the tank. The air pressure must be 2-3 PSI below the cut-on pressure.
  • You can use a regular tire gauge or a digital pressure gauge to check the pressure inside the water tank.
  • Install the water inlet and water outlet with the pump.
  • Turn on the circuit breaker and pressure pump switch.

That’s it. You have successfully replaced the well water pressure tank.

How does a Well Water Pressure Tank Work?

The primary purpose of installing a water tank with a well is to store water to supply water at constant pressure in your entire home. Water from the well enters the pressure tank and is then distributed to your home’s plumbing system.

Three types of pressure tanks are used for storing water in a well water system.

  • Air-over-water tanks
  • Diaphragm tanks
  • Bladder tanks

Air-Over-Water Tank: This type of tank works by maintaining a layer of air over water. The pressurized air over the water pushes down on the water to create the pressure needed to supply water to your home.

Air-over-water tanks were frequently used a few years ago, but their use is rapidly decreasing. These tanks appear larger than others but have a small capacity. The small capacity causes the pump to cycle on and off repeatedly and leads to premature failure.

Diaphragm Tanks: These tanks have two chambers inside a single tank. One chamber is dedicated to water, and the other is to air; a rubber diaphragm separates both chambers. The rubber diaphragm is permanently attached to the tank’s inside, rising or falling with the water level inside the chamber.

When the water enters the lower chamber, it pushes the diaphragm up. This triggers a switch that turns off the pump.

A couple of issues in this tank start showing up after a couple of years. The diaphragm gets loose or folds over itself. The only solution to both problems is replacing the water tank.

Bladder Tanks: The bladder pressure tanks use two separate chambers for water and air. These tanks have an air balloon that expands or contracts relative to the water volume in the tank.

These tanks are better than the two discussed above. They don’t have the issue of a diaphragm or single chamber tank because they are self-contained. Air and water don’t mix in the tanks, and you don’t need to add air to these tanks.

Bladder pressure tanks last longer than other pumps. However, they can develop problems as well. The most common issues with these types of pumps are failure of the internal bladder and the bladder not able to inflate.

How to Drain a Well Water Pressure Tank?

Emptying the well water pressure tank is an easy but time-consuming process. Here’s how you can do it.

  • Turn off the circuit breaker and the pressure switch.
  • Connect a garden hose with the water drain valve on the pressure tank.
  • Open the valve and let the water flow. You can also open a few nearby faucets to speed up the process f you have a large tank.
  • Notice the water coming out from the tank by putting the hose in a clean container so you can check if it has sediment in it.
  • If the water has sediment, you’ll need to run the pump for 30 seconds and then drain the water until all the sediment has been removed from the tank.

What Size Well Water Pressure Tank do I Need?

A right size pressure tank reduces the risk of premature pump failure by extending the time between the cycles.

Before calculating the pressure tank size, you need to know about the following 3 things.

Flow Rate: The flow rate is how many gallons your pump produces in one second.

Cut-in/Cut-out PSI: These are the pressure settings on your pump. They are usually given in 20/40, 30/50, and 40/60 settings.

Minimum Runtime (the time between cycles): This is the minimum time a pump runs between the cycles.

An easy way to determine your tank’s drawdown capacity is given below

Flow Rate x Runtime = Tank Drawdown Capacity

Please note that pumps with a flow rate or capacity up to 10 gallons a minute should have a tank with a minimum one-gallon drawdown capacity for each gallon per minute of the pump.

For example, a 10-gallon a minute pump and a tank with a 10-gallon drawdown capacity will work best.

Here is a sizing chart to help you find the right size for your pressure tank.

The following video will further educate you about calculating the right size of a well water pressure tank.

How to tell if your Well Water Pressure Tank is bad?

  • Fluctuation in water pressure
  • Noisy pressure tank
  • Spitting faucets
  • High electric bills
  • Damaged well pump

How to Fill or Adjust Well Water Pressure Tank?

The well water tank has water at the bottom and air at the top. This setup helps maintain constant pressure in your home.

You will need a pressure gauge and an air compressor to fill the water pressure tank with air. Find out the air valve on your tank. It is usually located on top of the valve. The air pressure inside the tank must be 2-3 PSI less than the cut-on pressure.

Adjust the air pressure as per the reading you get on the gauge. You should use a high-quality digital gauge so you get accurate measurements.


  • Roy Jones

    Roy lives in Anderson, Texas, and has been a part of various certified well drilling firms. He has extensive 20 years of working experience in water wells maintenance, repair, and drinking quality. Roy has been guiding neighbors on well issues and writes to educate private well owners about various well water issues.

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