What is the difference between a well tank and an expansion tank?

Author: Mr. Braxton Lehner Jr.  |  Last update: Wednesday, June 10, 2026

A water pressure tank for a well is designed to help maintain adequate pressure in your pipes without requiring your well pump to run nonstop. A water heater expansion tank is designed for use on modern plumbing systems. You can find more detailed information on these two types of pressure tanks below.

What is the life expectancy of a well expansion tank?

Average Lifespan

The typical lifespan of well pressure tanks is 10 to 15 years, though this can vary depending on the tank's quality and maintenance. Higher-quality tanks can last 5 to 30 years, with the average being around 15 years.

What is the purpose of an expansion tank?

The expansion tank is designed to handle the thermal expansion of water as it heats up in the water heater, preventing excessive water pressure. If water pressure gets too high, it can damage valves in plumbing fixtures, joints in supply pipes, and the water heater itself.

How do I know if I need an expansion tank?

Short answer? If your home has a “closed” plumbing system, then yes, you'll need an expansion tank.

Do I need an expansion tank on well water?

These devices are required on closed systems, which is public water. Expansion tanks or expansion valves are not required on wells.

What is a thermal expansion tank, and why do you need one?

What is the life expectancy of an expansion tank?

However, on average, an expansion tank can last 5 to 10 years or even longer if properly maintained and inspected regularly. It is recommended to check the expansion tank for signs of damage or wear, such as leaks or rust, at least once a year and replace it if necessary.

Can I run a well without a pressure tank?

Well pumps are still able to function without a pressure tank, but it's highly recommended to install a pressure tank because they increase the lifespan of your well pump. Well pumps aren't designed to operate rapidly or continually; when this happens, they tend to engage in something called water cycling.

How much is a new well tank?

Because of their slight downgrade in performance, expect to pay around $150 to $400 for a bladder well pressure tank. These tanks can reach upward of $1,500 for larger sizes.

Does a well pressure tank fill with water?

If the water inside your pressure tank is no longer being contained by the rubber bladder, your tank will fill with water. Pressure tanks are generally 70% filled with air, so when you knock on the tank it should sound hollow and empty.

Should an expansion tank be full of water?

Your expansion tank should be half full of water and air. Using a metal object, tap the top and bottom half of the tank. The sounds should be quite different, which indicates that your tank is filling up the way it should.

What happens if you don't install an expansion tank?

As plumbers know, the expansion tank equalizes pressure throughout the plumbing system by providing a space for hot water to flow into. Without an expansion tank, pressure would be distributed to the entire plumbing system, straining it and decreasing its lifespan.

How do you know if your expansion tank is failing?

Leaking Water:

If your expansion tank is showing signs of wear and tear due to age or other factors, it may develop leaks. Keep an eye out for any water leaking from the pipe at the top of the tank or around its vicinity. Should you notice any leaks, it's crucial to have the tank professionally assessed by a plumber.

What happens when a well expansion tank fails?

When a well pressure tank goes bad, the well pump and plumbing inside your home can suffer harmful consequences. Problems like water hammer, increased electricity bills, and well pump failure can all occur when your pressure tank fails.

How many psi should a well pressure tank have?

Most well tanks come set at 30/50. The cut-on pressure for the well pump is 30 psi, so the pressure of the tank should have a pressure of 28 psi. If your well tank is on a 40/60 pressure switch, your pressure setting should be 38 psi.

How do I know if I need a new well tank?

Common Signs of a Well Water Tank Problem

Unstable water pressure as the pump cycles on and off. A pump that runs less than 30 seconds to pressurize the tank. A pump that cycles on and off frequently or remains running. Water leaks at the pressure tank.

How much does it cost to replace an expansion tank?

A water heater expansion tank costs $150 to $450 on average, with a national average of $325. The total cost depends on the size and type of tank. A water heater expansion tank costs an average of $325 to install, and most people pay between $150 and $450 for the task.

How much does it cost to have a new pump put in a well?

Because of this, the range is $2,500 to $17,000. These costs would include all equipment, material and labor to install a basic well pump all the way to a high capacity deep well installation.

Can I replace my own well pressure tank?

Chances are it's time to replace your water well pressure tank. While this may sound like a job for a professional plumber, this is also something you can do yourself at home if you're handy with DIY plumbing.

How often should you drain a well pressure tank?

The tanks should be flushed semi-annually to remove accumulated sediments by opening the tank drain valve. These sediments could harbor and shield harmful microbes from chlorination should the well and home plumbing system require disinfection.

Are well pressure tanks buried?

The tank is typically buried in the ground near the well and is connected to the well pump and the home or business's water supply.

How do I know when my expansion tank needs to be replaced?

Signs It's Time to Replace an Expansion Tank

If the tank is no longer effectively maintaining or controlling this pressure, it indicates a malfunction. Loss of pressure control could mean that the internal air bladder or diaphragm has ruptured, or that the tank has lost its pre-charge.

How often should I drain my expansion tank?

Water will get inside of the system, of course, which means that you are going to need to drain expansion tank to make sure that the pressure that the tank absorbs is always at an optimum. This task shouldn't take very long, and should be done a couple of times a year by you or a professional.

Is an expansion tank required by code?

If you are on a "Closed" loop water system, you will be required to have a Thermal Expansion Tank installed on your water heater, the next time it is replaced or repaired.

Previous article
How do you know if a non stick pan is damaged?
Next article
What is the proper posture for sweeping?