The average lifespan of a well pressure tank is 15 years. This will however depend on the quality of the tank, water quality and whether the tank is properly sized. Pressure tanks can last for a short as 5 years or as long as 30 years.
The point I am making here is that well pressure tanks will not last forever. So, how do you know if your pressure tank is bad and that it is time to buy a new one?
If you have no water or the water pressure is low, the well pump is short-cycling or the pressure tank is waterlogged, the pressure tank is bad and will need to be replaced. A bad pressure tank will cause the pump to fail prematurely if it’s not replaced.
The best and quickest way to test if a pressure tank is waterlogged is by tapping it with your hand. If it sounds solid (not hollow at the top), it is a sign that the bladder or diaphragm has ruptured and therefore waterlogged.
How Well Pressure Tanks Work
There are 2 main types of pressure tanks. These are bladder and diaphragm pressure tanks. Both work the same way and most people don’t even know the one they have.
A bladder pressure tank as its name implies has a balloon-like bladder at the bottom of the tank The outside of the bladder is filled by compressed air.
As the bladder fills with water, the air is compressed even further, allowing the water to be stored under pressure. If you have a bladder pressure tank, you can replace the bladder if it is ruptured instead of replacing the entire tank.
A diaphragm pressure tank has a watertight diaphragm around the mid-section of the tank. Just like with bladder pressure tank, the water occupies the bottom half of the tank while the compressed air is at the top.
Your pressure tank operates between 2 pressures set by the pressure switch. These are the cut-in and the cut-off pressure. The cut-in pressure is the low pressure setting while the cut-off pressure is the high pressure setting.
There is usually a 20 psi difference between the cut-in and cut-off pressure. If for instance your cut-in pressure is 30 psi, the cut-off pressure will be 50 psi. A cut-in pressure of 40 psi means a cut-off pressure of 60 psi.
The pressure switch basically turns the pump on and off in accordance with the water pressure inside the pressure tank.
When the water pressure in the tank drops below the cut-in pressure, the pressure switch activates the pump to start filling the tank with water. The pressure switch turns off the pump when the pressure in the tank gets to the cut-off pressure.
Pressure tanks have an air inlet at the top that allows you to add air into the tank. The air pressure in the tank should be 2 psi below that of the cut-in pressure.
Signs Your Pressure Tank is Bad
A bad well pressure tank will communicate to you through several ways. The following are the telltale signs that your pressure tank is bad and will need to be replaced.
1. The Water Tank Is Waterlogged
There should be a clear separation of the water in the pressure tank from the compressed air. It is the compressed air which gives the tank the ability to store water under pressure.
A waterlogged pressure tanks means that the entire tank is full of water. This is caused by a ruptured diaphragm or bladder and as a result the air is dissolved in the water.
When your pressure tank’s bladder or diaphragm raptures, you will not notice it immediately. In the first few days the bladder/diaphragm tank will behave like a galvanized (air-over-water pressure tank).
Before bladder and diaphragm tanks were invented, people used big galvanized tanks which are also known as air-over-water pressure tanks. Read more on the the different types of pressure tanks in this post.
Before filing the tank with water, the tank would be filled with compressed air. This tank has bladder or diaphragm. It is all hollow.
When the tank was finally filled with water, the water would compress the air at the top of the tank. With time however, the air would dissolve in the water and the tank would then need to be recharged.
A ruptured bladder or diaphragm pressure tank will therefore act like these tanks the first few days. As the air however becomes dissolved in the water, the entire tank will be fully waterlogged.
To test if the pressure tank is waterlogged, remove the cap from the air inlet valve at the top of the tank. Use your finger to try and bleed off air from the tank by pushing the piston inside. If water comes out instead of air, your pressure tank is waterlogged and you will need to replace it.
Another thing you can do is to try and tap the tank from the bottom to the top. You would expect the top of the tank which is supposed to be filled with air to sound hollow. If it however sounds solid, the tank is waterlogged.
2. Your Water Pump Is Short-Cycling
If your water pumps comes on and off frequently (known as short-cycling), it is a sign of a bad pressure tank. It is means the pressure tank is unable to hold water for a large drawdown, which is often as a result of a waterlogged tank.
Pressure tanks are usually made of steel. When the tank is waterlogged, any water demand in the house like flushing the tank will result in a short-cycle from the pump in a bid to compensate for the lost water.
Unlike air, steel cannot be compressed. Any water drawn from the tank will therefore mean that the pressure tank needs to turn the pump on but since the tank cannot expand, the pump will only be on for a few seconds.
If your well pump is short-cycling, you need to turn off power to it at the electrical panel and contact a professional or troubleshoot the problem on your own. A short-cycling pump will fail prematurely which will be another expensive replacement for you.
3. Jumpy Pressure Gauge Needle
Some pumps are not as loud others and you may therefore not be in a position to hear yours come on and off. Something you can do in this case is to monitor your pressure tank’s pressure gauge.
You pressure tank will have a nearby pressure gauge which shows the exact pressure of the water in the tank. The needle of the pressure gauge moves between the cut-in and the cut-off pressure.
If you notice that the needle is bouncing off between the cut-in and cut-off pressure, you definitely have a problem with your pressure tank. Again, this points out to a waterlogged tank.
4. No Water or Low Water Pressure
The first sign you are more likely to notice when you have a bad pressure tank is low water pressure or no water at all in the house. This can however be caused by a bad pump or a faulty pressure switch so it is not isolated to the pressure tank.
If you use well water and you suddenly notice that you have low water pressure or you have no water at all, the pressure tank should be the first place you check after confirming that the well pump electric breaker is on.
Check if the pressure tank is waterlogged by tapping it from the top to the bottom. If the pressure tank looks good, you could be having a bad pressure switch or you may need to replace the pump.
I have written a detailed post on the signs that you need to replace your water pump. Read it here.
The Best well Pressure Tank
If you would like to replace your old/waterlogged pressure tank with a new one, the Well-x-trol Amtrol wx 202 pressure tank would be my recommendation.
Amtrol in my opinion makes the best well pressure tanks although they are slightly more expensive than other brands. Even though this is just one model, there are more to choose from especially when it comes to size.
In case you do not know what size of pressure tank is the best for your household, I have written a separate blog on how to size a pressure tank. Read it here.