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How to Troubleshoot Low Water Pressure On Well Water Systems

Episode 15. How to Troubleshoot Low Water Pressure On Well Water Systems

Read or Listen to See How to troubleshoot Low Water Pressure On Well Water.

Today’s episode is all about how to troubleshoot low water pressure on well water for homes and small businesses.

Do you have plenty of water, but experience low water pressure?  This is a common problem.

I put together a Checklist and quick Troubleshooting guide called “How to Troubleshoot Low Water Pressure On Well Water.”  This free guide includes pictures, checklists, and things to look for in trying to troubleshoot low water pressure (see link below to get your guide).

Discussed during this episode:

1. What is water pressure and what is the difference between water pressure, and flow rate?

2. How to find out what your water pressure and the flow rate is now, before any water treatment systems or plumbing.

3. How to Troubleshoot common problems with low water pressure and flow rate.

4. How to read a filter pressure drop chart and a pump curve charts.

5. How to size whole house filters, automatic backwash filters, and softeners to avoid pressure drop problems.

6. What is water pressure and what is the difference between water pressure, and flow rate?


What is Water Pressure?

Water in residential plumbing systems is “under pressure”, that is, it is pressurized by either gravity or a pump to give you the flow and pressure you need.

In the U.S. and Canada, the pressure is typically measured in Pounds Per Square Inch, which is referred to as PSI.

Pressure is how many pounds per square inch your water is under. So for example, if you had a storage tank 100 feet in elevation above your house, you would have 43 PSI. So for every 10 feet its higher (referred to as Head) you will have 4.3 PSI.

The pressure would be the same if you had a million gallon storage tank, or a 1000 gallon storage tank on a hill 100 feet above your house. The pressure would still be 43 psi. But for many of us on residential well systems, we don’t have gravity flow we have a submersible pump that is used to build up water pressure. The higher the pressure you have, the more flow (up to a point) can flow through a pipe of a given size.

Most modern homes and appliances like to have at least 30 PSI, however, 50 to 60 is much better. Generally, most appliances don’t like to see more than 70 PSI because it can damage some appliances.  Water pressure is easy to measure with a pressure gauge. Most home well systems will have at least one pressure gauges, usually somewhere on the pipe near your pressure tank.

You can easily find out what the PSI is by just looking the pressure gauge and noting the PSI. The pressure tank might turn on at one PSI and off at a different pressure, say on at 30 and off at 50 PSI.  Knowing what your water pressure is can help you troubleshoot low water pressure on well water.

What is Flow Rate?

Flow rate can be thought of in terms of gallons per minute flowing through a pipe. A common residential well pump might deliver anywhere from 5 to 20 gallons in one minute.  Pressure is not the same as flow, however.

As an example: You could have great water pressure coming from the well, but terrible flow rate and reduced water pressure in the home.

Most pipes in standard homes are ½”, ¾” or 1” in diameter. Say you had really great water pressure of 60 or 70 PSI, and your home had all ½” piping, and you had 3 bathrooms all being used at the same time, or you had a large spa type bathtub that likes to be filled at 15 gallons per minute. Because you have ½” piping, you might experience low flow rate, even if you have 70 PSI to start with because the flow rate needed requires a larger diameter pipe.

How to Find Out Your Well Pumps Flow Rate

If you get a chance, listen to Episode 2 where I discuss how easy it is to find out your well pump flow rate, and what flow rate is. I am putting a link in the show notes as well, which goes to a page that shows how to easily check your well flow rate. Basically, the flow rate is gallons per minute, that is, how many gallons can flow in one minute.

Link to Flow Rate Calculator Page:

Pumps are set to typically turn on at one pressure automatically and off at a higher pressure, usually 20 PSI higher than the low pressure.

We are talking about standard submersible well pumps or booster pumps that are single speed. Some folks use a ‘constant pressure system’ where it maintains a constant pressure in the home, and these use variable speed motors and do not fluctuate between a high and low.

Standard systems use a pressure switch to turn on and off the well pump. If you measure the drawdown from your pressure tank in gallons and determine how fast the well pump refills it, you can easily know what the flow rate is in gallons per minute.

Here are the steps:

1. Measure the number of gallons drawn down from the pressure tank until the well pump turns on.

2. When you hear the pump turn on, immediately close the hose bib.

3. Time the period in seconds it takes for the well pump to build back up to pressure that is, between the cut- in and cut- out of the pressure switch. The pressure switch turns on the pump at a lower pressure and turns off the pump when it reaches a higher pressure.

4. The simple formula for determining the flow rate is gallons drawn down (that were measured above), divided by the seconds required for recovery, then multiplied by 60:
(Gallons / Seconds) x 60 = Gallons per Minute (GPM) flow rate..

For example, if 20 gallons are drawn down and it takes 120 seconds to build pressure back up, then: 20 divided by 120 = .166. Then multiply .166 x 60 = 10 gallons per minute flow rate.

So in this example, you have 10 GPM flow rate

Check List: Steps To Take to Troubleshoot Low Water Pressure On Well Water Systems

Some common problems to look for are:

       1. Low flow coming from the well pump.

This can be caused by an aging well pump wearing out, clogged well screens, or a partially stuck check valve, broken well pipe, or corroded well pipe. For well water problems it’s best to consult a well professional. We recommend the national groundwater association, www.wellowner.org to locate one in your area.

2. Pressure switch set too low, or bad pressure switch.

For standard systems, one question we get is: can I turn up the pressure switch, or adjust the pressure switch to get higher pressure?  Yes, you can adjust the pressure switch, however, you have to be careful because when you adjust it, it decreases the amount of drawdown in the pressure tank.  Your well pump may not be able to build higher pressure than what your pressure switch is set to, so adjusting it higher might not work.

Pressure switches may need to be cleaned and inspected to make sure there are no ants or insects present.  This is best done by a professional as there are live wires inside.

3. Failed pressure tank or low pressure in the captive air tank.
Your pressure tank has a captive air bladder or diaphragm, which holds a certain pre-charged amount of air pressure. To check it, turn off the well pump power, and drain out any water pressure in the tank by opening a hose bib or faucet. The pressure switch can also be bad, that is a very common problem.

4. Clogged piping.

You might need a plumber or well contractor to identify this, but one way to tell if it is your plumbing is to take out a section of the pipe and look inside. Is it filled with orange sludge, or scale or sediment? This can cut way back on your water pressure.

5. Partially clogged or stuck gate valves.

Gate valves and ball valves need to get turned on and off periodically.  Sometimes gate valves get stuck and cannot open or close, especially if they have not been used for a long time.   Replace these types of bad valves.   If the valve is full of sludge it can be cleaned, but generally replacing it is better.

6. Clogged or malfunctioning pressure regulators.

You may have a pressure regulator on the main pipe coming into the home. These can go bad or become fouled with sediment or rust over many years and may need to be replaced.

7. Clogged aerators, shower heads, faucets or fixtures.

Remove faucet aerators and shower heads and see if those are plugged with scale or sediment.  You might have good water pressure and flow but have partially clogged aerators.  These can be cleaned with vinegar or citric acid or replaced to restore pressure.

8. Poorly sized or clogged or malfunctioning filter cartridges, water softener or iron filters etc.

Check and change filter cartridges and inspect your backwashing filters and water softeners if you have them. Check pressure before and after to troubleshoot if you have a problem with pressure loss through your filter system.

How to Read a Filter Pressure Drop Chart and Pump Curve Chart

Here is a filter pressure drop chart, from Pentek for one of their filter cartridges:

It is a pretty simple chart or coordinate grid, with the X-axis (the lines running across the bottom) and the Y-axis, (the lines running up the left side). You can see the flow rate across the bottom and the pressure drop up the left side.

For example, at 10 gallons per minute, this filter cartridge will create a 1.0 PSI drop when its new.

Here is a Pump Curve Chart for a Goulds Pump:

You can see in the chart, the flow rate is at the bottom and the elevation (head) in feet and meters up the left side.  The point on the chart where the flow rate and head intersect, can you tell how many gallons per minute that pump can do at a given pressure.   To translate the head in feet to PSI, just multiply the feet times 0.43.   For example, 100 feet will get you 43 PSI.

How to Select and Size Automatic Backwash Filters and Water Softeners to Avoid Pressure Problems

The first step is to check with and follow the water treatment manufacturer’s recommendations. They will often tell you what the maximum flow rate is, in gallons per minute.

Another point is, don’t use a filter or softener that will cut back on the size of the pipe. So if you have a large home, or need to fill a swimming pool or commercial application, generally, you don’t want to put a filter that has a ¾” pipe size, on plumbing that uses 1” or say 1-¼” piping.

You want to use a system that can filter and treat your water without restricting your flow rate and cut back on water pressure.

The chart above shows you the service flow rate of various filter media and water softener resin. One common way to size filter and softeners is based on the square footage or surface area of the top of the tank.  For example, a filter tank that is 14″ in diameter, has a top of the filter media surface area of 1.07 square foot.

If you selected a filter media that can work well at 5 gallons per minute per square foot, and you have a 1 square foot filter you can then filter well at 5 GPM.   The chart above shows the “service flow rate” for various media, which is the flow rate if you were filtering for hours at a time.  However, for homes, most of the filter media below can filter at 2 – 3 times the service flow rate for a short time (the Peak Flow Rate or Maximum Flow Rate) and still perform well.

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  • Clean Water Systems & Stores, Inc., Water Treatment Equipment,Service & Supplies, Santa Cruz, CA

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