Add a Water Pressure Tank - avoid unnecessary well pump replacement

Water pressure tanks in my well water system.

If you have a water well, installing an additional water pressure tank will be of interest to you. Having more than one precharged water system tank can help extend the life of your well pump motor and controls, and obviate unnecessary replacement.

Avoiding a well service call could save you $150. Avoiding a well pump replacement could save you $2,000. Saving that kind of money should be important to everyone with a well water system.

Let me overview the system and then I'll discuss the problem that can lead to premature well pump and control circuit failure, and what I believe to be the most cost-effective solution.

The System

A typical pressurized well water pump system consists of a submersible pump and motor that feeds water to a holding tank. The holding tank retains the water in a vinyl bladder. The original holding tank for my system is the burgundy colored tank shown in the photo below.

The water in the bladder is held under pressure by air that is trapped between the metal tank and the top of the vinyl bladder. The air is pumped up (precharged) to a specific pressure. A valve, much like that found on a bicycle inner tube, allows the user to regulate precharge pressure on the air side of the bladder.

A water pressure tank is essential for continuous water pressure from the well to the house. Here are two size tanks plumbed into the same system.

The photo to the left shows two of the five tanks in my system. The black valve in the upper right of the blue tank allows precharge to be checked and modified.

Higher precharge provides higher flow rates but lower water capacity. This means frequent pump starts.

Lower precharge provides lower flow rates but more water capacity. This means infrequent pump starts.

A pressure switch monitors water pressure in the system and turns on the well pump when the pressure is low. The pressure switch also shuts off the well pump when the water pressure tank reaches a sufficiently high pressure. The pressure switch is adjustable for both the low "cut on" pressure and the high "cut off" pressure.

Filling of a water pressure tank is controlled by the pressure switch, shown here with the system pressure gauge.

The photo to the left shows the pressure switch (gray housing) mounted to the main water line (header) to monitor system pressure.

The photo also shows isolation valves associated with several tanks and unions on the far left and far right for removing the tanks from service if needs be.

There may also be filters in the system to remove particulate from the water, and check valves to keep the water from flowing back into the well due to pressure exerted by the water pressure tank.

A water pressure tank is filled by pumping well water through the sand screen and filter element shown in this photo.

The photo above shows flow from my well pump from left to right. The water flow comes up from the pump and goes through a sand screen, then fine particulate filter, then a check valve, union, isolation valve, and then a second check valve. To the far right the house water is fed by the pipe going up, and the water pressure tank(s) are fed by the pipe going down.

Well pump control box containing the starting and running capacitors that are protected by reduction in number of well starts.

The photo to the right shows the pump motor control box mounted on the wall. It contains a starting and a running capacitor and a control circuit. The starting capacitor helps boost the power delivered to the pump in order to get it started. The running capacitor helps balance the load while the motor is running.

The yellow cable is "switched" power from the pressure switch. The white cable runs outside underground to power the pump motor.

The Problem

The preventable "wear and tear" on system components is seen by the capacitors and the well pump motor. Except for the pump impeller, these are the most active components in the system.

Frequent and repeated starts stress both the starting and running capacitors. Constant running has no effect on the starting capacitor and minimal effect on the running capacitor.

Frequent and repeated starts place electrical and mechanical stress on the well pump motor as it is brought from a dead stop to full speed in a matter of moments. Think of a light bulb being turned on and off repeatedly - it places stress on the filament and this shortens the life of the bulb.

The Solution

Installing an additional water pressure tank will give your system more capacity, and therefore the demand for a pump start will be less frequent. For each water pressure tank you install, you reduce the need for well pump starts.

When I first bought my house in 2002, it had a single 36 gallon water pressure tank. (This small burgundy colored tank is seen in the second photo from the top.) The system would turn on almost anytime there was a demand for water, even a minor demand.

My running capacitor failed only a few months after I moved in.

I then revised the system to add four 85 gallon water pressure tanks in addition to the original 36 gallon tank. Now the system can operate all day, or even a couple days without the pump turning on. This should extend the life of my pump motor and controls considerably.

There hasn't been a failure since I revised my system over ten years ago.

Of course, the pump will come on each day if I am doing loads of laundry, taking long showers, or watering the yard. In these cases, the pump must come on to make up for the heavy draw down on the pressure tanks.

Otherwise, the pump stays idle while the water pressure tanks provide water for the minor demands throughout the day.

If you are installing one or more pressure tanks, you'll need to set the air pressure for all tanks to be the same. This is done when the system is completely drained of water and the pump is shut off. Tank precharge pressure should be about 2 psi below the pressure switch setting that starts the pump.

Costs and Benefits

Large water pressure tanks cost about $325, so you might want to install just one additional tank. Even just one additional tank should be a big help. It should cut your pump starts in half and that could as much as double the useful life of your pump.

Even the manufacturer can't tell you what the exact benefits will be, but there is general consensus among professionals that having an additional water pressure tank will help ensure that your pump has a long life expectancy. Here is what Flotec has to say about their largest residential water pressure tank:

The storage tank provides "...greater water capacity between pump cycles for maximum system life."

I installed 4 tanks several years ago, so my costs were about $1,200 when you take into consideration all the plumbing fittings and fixtures I had to buy. My hope is that I will prevent the need to replace my well pump because of failures attributable to excessive starts.

If I prevent one well pump replacement to the tune of thousands of dollars, it will all be worthwhile. When a well pump fails because of frequent and repeated starts, it's too late to think about doing something to prevent it. That's why my ounce of prevention is already in place.

Well pumps can have a high price tag, but that's not the entire cost of their replacement. Usually, the cost of new piping, new wiring, and the labor and equipment usage charges are at least as much as the cost of a new submersible pump.

In the event of a power failure, my water system can provide plenty of water for days if needs be, because I have ample pressurized storage capacity. In the meantime, my neighbors will have run out of water after a single flush of a toilet.

I tend to live my life with an eye toward being prepared so I don't have the cost of reacting to a situation that can easily and cost-effectively be prevented. As you might imagine, reacting to an emergency can be much more costly than calmly avoiding, forestalling or preventing it to begin with...and, it's done on my terms.

Done with Water Pressure Tank, take me back to Frugal Living Tips

Knowing how a system works is a key to being able to operate it properly, provide proper maintenance, diagnose problems correctly, and perform repairs yourself.

In the event you're looking for more help than I'm offering here, take a look at these additional resources, as they might might be of interest to you.