Well Pressure Tank Guide: (DIY) Problems, Sizing, Types, PSI

How often do you replace a well pump?That will depend upon if the well pressure tank is operating properly. If the pressure tank fails, the pump won’t last much longer either. Here is how to save money and prevent major headaches.

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You Can Save Money by Checking For Well Pressure Tank Problems

Don’t put this off. Check the pumping system regularly. Few things can ruin your day faster than not having water, and having your bank account drained too.

How Do Well Pressure Tanks Work?

Well pressure tanks do a lot of work for a submerged water pump in a well, or a shallow well pump. A well pressure tank holds an amount of water that can be used by your household immediately. When you turn on a faucet or a shower, the water comes directly from the pressure tank.

Water stored in a pressure tank for a well reduces the number of times a well pump has to switch on, and this reduces wear and tear on the well pump. Generally, replacing a well pump is very expensive. Therefore, making it important to ensure that pressure water tanks remain in good working condition. So, you save money by preventing a well pump from working excessively.

Shallow well pump and pressure tank.

Most water pressure tanks contain a “bladder” inside them. The bladder’s function is to regulate the water pressure in the tank and it pushes the water through the pipes in a plumbing system when an appliance or faucet is turned on. If the bladder breaks, water will flow into it and pressure in the water pressure tank will decrease. This will result in the water pump turning off and on more inconsistently and frequently.

This is a problem as water pumps are not designed to turn off and on constantly. The frequent turning off and on will result in much more wear and tear than normal and this will lead to a decreased lifespan. If the pump breaks, you won’t have any water supply to your house and the repair bill can be very high.

Replacing a water well pump typically costs in the region of $2,000. Actual costs depend upon the type of well pump, and how deep the pump is located.

Check Your Pressurized Water Tank Regularly To Prevent Well Pump Failure

This problem can be avoided completely if routine checks are done on your water well pressure tank. Before calling a water well professional, there is a quick test you can do to determine if your pressure tank is functioning as it should.

Before performing the test, check if your well water pressure tank operates at a pressure of 30/50 psi or 40/60 psi.

  1. Find another person to help you, and make sure you have a timer on your smartphone or a stopwatch available.
  2. Ask your helper to stand at a faucet while you check the water pump tank.
  3. Locate the pressure gauge situated on the bottom of the tank. This gauge will typically fluctuate between 5psi and 10 psi.
  4. Ask your helper to turn on the faucet they’re at for a few minutes while you watch the pressure gauge. The needle should move to the low setting slowly.
  5. When the pressure reaches the low setting, start the timer and stop it when the pressure reaches the high setting. If the pressure reached the high setting in less than a minute, there is a problem with the well water tank.

If the pressure moves from low to high in less than a minute, call a water well professional, as it’s very likely you’ll need a new pressure tank. However, a pressure tank is much cheaper than what a water well pump would cost, so the bill shouldn’t be that bad. A water well professional will be able to give you different options for well water pressure tanks depending on your household’s needs.  

Does The Well Pressure Tank May Need To Be Replaced?

Pressurized well water tanks often cause problems leaving the homeowner with no water at all or inconsistent water pressure. Well tank problems are often difficult to fix, and they may even have to be replaced.

If you are using a well system, knowing the signs of a well tank problem may help you prevent bigger system damages from happening. First, we need to understand the working relationship between the pump and the pressure tank.

How Pressure Tanks and Well Pumps Work Together

A well pump and a well pressure tank work together much like a generator and a battery do. The pump creates the pressure (generator), while the pressure tank stores the pressure (battery).

When your pressure tank doesn’t work as it should, the well pump is forced to work when it shouldn’t have to. When the pump starts cycling on and off frequently, it WILL eventually be damaged. Then the repair bill may be 3X what it needed to be. 

How Long Do Well Pressure Tanks Last?

The most common pressure tanks used today are the bladder type. It maintains water pressure, protects against water hammer, and reduces pump cycling. 

Several factors determine how long bladder pressure tanks typically last. Cheaper, low-quality pressure tanks typically last 5 years (check the warranty). While a high-quality pressure tank with a 7 year warranty may last for as long as 30 years. On average, a tank lasts 15 years, providing it is sized properly and the water is clean.

The lifetime of a pressure tank is also determined by the quality of the water that is pumped from the well. If the water regularly contains sand or silt, the sediment will be abrasive on the pressure tank’s diaphragm and create holes.

“Cycling” is where the pump turns on and off frequently. Which will wear out the tank faster than it would normally. Pressure tanks are designed to limit pump cycling via a layer of air above the tank’s water level. When a faucet or shower is turned on, the amount of air in the tank increased as the water flows out, and this reduces the air pressure.

When the pressure reaches the cycle-on pressure, the pump switches on to restore water pressure by refilling the tank with water. If this cycling occurs frequently or rapidly, it could cause the pressure tank’s bladder to be damaged.

The cycle on pressure is most commonly 30 PSI, but it could be 20 PSI, 40 PSI, or even 50 PSI depending upon the brand of regulator and the tank being used.

Pressure Tank Troubleshooting

A professional water well contractor should be contacted if any of the signs described below are noticed:

  • The top of the tank is filled with water. Knocking on the top of a pressure tank should produce a hollow sound. If it sounds like the tank is full, there is a problem with water pressure. Which results in the pump turning on more frequently.
  • Pressure fluctuates wildly – If the needle on the pressure gauge bounces between high and low over a range of about 20 psi within a period of 20 seconds to 2 minutes, there is a problem. The pressure should only go down when a faucet is turned on. If the pump turns on and off more than once in 30 seconds, there is a problem.
  • The diaphragm is blown – If the pressure is less than 10 psi, the diaphragm is likely blown.
  • Water tank pressure. Switch the pump off manually and drain all the water out of the tank. With the pressure tank empty, the pressure should be 2 psi lower than than the pressure at which the pump turns on. This is most often 28 psi, but depending on the pressure switch setting, it could be 38 or 48 psi. 

A Pressure Tank’s Role in a Well System

A pressure tank is a major component in a well system, together with the well itself, pressure switch, and pump. It is used to store well water and it supplies water to the home at appropriate pressures.

In areas without water services regulated by a city, a well is required to supply running water to the house. Well pumps, either jet type or submersible, deliver water from the well to the plumbing system inside a home.

The well pump pumps water to a well pressure tank, which functions as a storage area before the water is distributed throughout the home. Compressed air is used to pressurize a well tank. This regulates the water pressure available in the home but also signals the pump when it should switch on to refill the tank.

Pressure Tank Operation

A pressure tank contains water and compressed air above the water. The compressed air pushes the water down, and when a faucet is turned on, the water flows out of the tank and into the plumbing system at an even rate.

The pump pushes water from the well into the bottom of the tank. As the tank fills up, the air in the tank above the water is compressed. When the preset maximum pressure is reached (typically 40, 50, 60, 70 PSI), the pump is automatically switched off.

14-Gallon Horizontal Precharged Diaphragm Well Tank from Red Lion permits the well pump to be mounted on top of the tank. Click Here

When water is used in the home, the compressed air pushes the water out of the tank. As the water level drops, the air pressure decreases and when it reaches the preset minimum (typically 20, 30, 40, 50 PSI), the pump is automatically switched on and the water replenished.

Pressure Tank Benefits

Pressure tanks not only regulate water pressure but also provide instant access to well water without a pump having to be switched on manually. It also allows well water to be drawn without the pump having to be switched on and off every time. This reduces pump operation and prolongs its life.

Well pumps use water storage tanks to provide consistent water pressure and sufficient water flow. Well tank sizes vary between 14 and 119 gallons. The tank reduces well pump run times, resulting in increased efficiency and lifetime. Well pumps wear out much faster if they frequently turn on and off and run for short periods.

Bigger tanks reduce pump switch frequency. A pump needs to run longer to fill a bigger tank, which is good for a pump’s efficiency. However, if a tank is too big for the home, this may cause the water to stagnate, resulting in an odd taste or other negative effects.

When deciding on which size well pressure tank is suitable for your home, remember that the holding capacity of the tank doesn’t equal the amount of water you’ll be able to use before the pump switches on. This amount is known as draw-down and it is typically less than 1/2 the tank capacity.

In most cases, you’ll only get about 1/3 of the tank’s capacity in draw-down. Your pressure tank has to be big enough to cater to the pump’s output and allow it to run for at least 1 minute at a time. Water pressure tank sizing can be tricky. More about that in just a bit.

Pressure Tank Types

There are three types of pressure tanks:

  • Bladder tanks. These tanks have a balloon-like bladder in which the water is contained. It expands when water is pumped into the tank, resulting in the air being compressed.

The bladder contracts and expands and this triggers a sensor that activates or deactivates the pump. Bladders are self-contained and can’t dislodge or fold under the compressed air’s pressure. Bladders also normally last longer than diaphragms.

  • Diaphragm tanks. This type of tank contains a vinyl or rubber diaphragm that separates the air and water. The diaphragm is pushed up into the compressed air chamber when water is pumped into the tank and this triggers a sensor to switch the pump off.

Great for seaside or other corrosive locations. 19.8 gallons Wellmate WM-6 / WM0075QC bladder type Fiberglass Tank, Quick Connections. Click Here

32 gallon diaphragm type well water tank from Amtrol, the WX-203 X-Trol. Click Here

Although efficient, this type of tank is prone to issues when the diaphragm dislodges from the tank’s sides, resulting in water flowing into the compressed air chamber. This will prevent the pressure from building. When this occurs, water pressure decreases drastically and the tank needs to be replaced.

Also, issues have also been reported with the diaphragm folding and causing faulty pressure readings. This could burn out the pump and ruin the tank.

  • Air-over-water tanks. These tanks don’t have a physical barrier between the air and water. This simple design is normally manufactured from galvanized metal and it’s often used in older homes. Nowadays, this type is not as popular as other pressure tank types.

Although this type of tank is normally bigger than modern models, its capacity is similar to much smaller tanks. However, one disadvantage of this type of pressure tank is that the air will dissolve into the water over time. Meaning that it has to be monitored and charged with air regularly.

Water Pressure Tank Sizing: 2 Rules of Thumb

#1. Count the number of fixtures in your home, i.e. showers, sinks, dishwasher, toilets, washing machines, faucets, outside faucets, etc., and multiply this number by 3. A house with for example 9 fixtures would require a 9 x 3 = 27-Gallon tank. We suggest the 32-gallon WaterWorker HT-32B Vertical Pressure Well Tank or the larger

WaterWorker 153921 44Gal Vertical Well Tank for this application.

#2. Before calculating the size of a tank, several input data points are required to size a pressure tank properly:

  1. Flow Rate (gallons per minute provided by the well pump)
  2. Cut-out/Cut-in Pressure
  3. Target Running Time

Most manufacturers recommend a run time of a minute if the power of the pump is less than 1HP.  If the pump is more than 1HP, a run-time of 2 minutes or longer is a good guideline to follow.  However, as guidelines are different, confirm this with the tank manufacturer.

These guidelines can be used to size a pressure tank:

  1. Up to 10 GPM: a drawdown of 1 gallon per GPM of water flowing
  2. Between 10 and 20 GPM: a drawdown of 1.5 gallons per GPM of water flowing
  3. More than 20 GPM: a drawdown of 2 gallons per GPM of water flowing

Drawdown is defined as the volume of water taken from the tank as the plumbing system is fed water while losing air pressure.

The purpose of a pressure tank is to maintain system pressure and minimize pump running time. Although a pressure tank may seem costly, it will save money in the long run. A pump running less will mean less maintenance and lower energy costs.

Pressure tanks are orientated in two standard ways: vertical and horizontal.  Ensure that you know which orientation is most suitable for your plumbing.

The last step is to determine the cut-out/cut-in pressure the system needs to be set at.

Well Tank Size and Pressure Are Related

A higher operating pressure needs a bigger tank. Tank size and pressure are directly correlated – as one increases so does the other.  A higher pressure setting results in a lower drawdown and a bigger tank is therefore required.

Common Pressure Switch Settings

Commonly available cut in (start)/cut out (stop) pressure tank ratings are: 20/40 psi, 30/50 psi ,40/60 psi, and 50-70psi

Pressure Switch Operation Explained

A pressure tank uses a pressure switch that monitors the tank pressure. Depending on the pressure in the tank, the pressure switch will switch the well pump on and off.

Most pressure tanks are configured so that the pressure switch switches the pump on at 30 pounds of pressure and switches it off at 50 pounds of pressure. The pressure gauge on the tank will indicate when the maximum pressure is reached and the switch will then shut off the pump automatically.

Best Water Pressure Tank Sizing Details

When a pressure tank is sized, the following equation is used:

Tank Draw Down Capacity = Flow Rate X Run Time

Example:

A pump has a flow rate of 4 GPM and uses a ¾ HP motor.  As the pump motor is smaller than 1 HP, the manufacturer will likely recommend a runtime of a minute.  The system needs to turn on (cut-in) at 40 psi and turn off (cut-out) at 60 psi.

4 (Flowrate) X 1 (Runtime) = 4 gallons of drawdown (at 40/60 psi or 30/50 psi)

This means a tank with 4 gallons of drawdown at a pressure setting of 40 psi cut-in and 60 psi cut-out will be suitable.

A suitable vertical tank would be the Amtrol 20 Gallon Well-X-Trol free standing water well pressure tank.

Vertical 20 gallon Well-X-Trol pressure tank. Check the price – Click Here Now

If a horizontal tank is preferred, the Flotec Horizontal 19-gallon capacity tank would be suitable.  This would provide 4.75 minutes of run time before the pump switches back on.

Great for smaller spaces where the pump is placed on top of the tank. Click Here

Horizontal pressure tanks are provided with metal or plastic pump stands to place the pump on, that help maximize space when the plumbing system is designed.

Related article: Well X Trol WX 202: Is It Worth The Price?

American Ground Water Trust

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Well Pressure Tank Guide: (DIY) Problems, Sizing, Types, PSI
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Well Pressure Tank Guide: (DIY) Problems, Sizing, Types, PSI
Description
A well pressure tank is critical for best well pump operation. Pressure switch settings are related to tank size and must be properly sized.
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All Water Products
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