Check valves on water supply systems: FAQs

Questions & answers about water supply piping check valves used on both municipal water supply piping and on private pump and well water supply systems.

These check valve FAQs help in the selection, installation and troubleshooting of various types of water system check valves and backflow preventer valves and foot valves.

Questions & Answers about Water Supply System Backflow Preventers & Check Valves - FAQs

These questions and answers about check valves and backflow preveners used on water supply systems were posted originally at CHECK VALVES, WATER SUPPLY, DRAINS, PUMPS - be sure to read that article too.

On 2019-12-28 by (mod) - are check valves prohibited at water tanks?

Douglas

I don't know where you heard that, but check valves are used regularly on well systems - otherwise water would flow backwards into the well and on a one line system would lose prime and the system would stop working.

A deep well may in fact use multiple check valves on the well riser line in the well too.

On 2019-12-25 by douglas

I've heard a check valve, back flow preventer is illegal on a well pressure tank

On 2019-11-13 by (mod) -

Yes Wayne but this sounds pretty strange; when faucets are shut off and your irrigation system pump is running it ought to have a hard time sucking water out of the house water supply piping unless there are open fixtures or air leaks into the system.

On 2019-11-12 by Wayne

I have an irrigation system with a booster pump and city water. When the pump runs it drains my home if it’s water in the pipes. Can I put a check valve in the main supply to prevent this?

On 2019-02-04 by (mod) - I'm trying to stop the pump from starting ever 2 minutes

Take a look in the ARTICLE INDEX to find the articles on diagnosing SHORT CYCLING well pump. That's the best place to start before even thinking about adding another check valve.

On 2019-02-02 by Kevin

I see no air in the water, as I had mentioned the pump starts at 30 psi, shuts off at 53 psi, 2 minutes later, it starts again

I'm trying to stop the pump from starting ever 2 minutes, I thought that if I could stop the pressure tank from draining and loosing pressure at the gauge , I was thinking of installing the check valve, to prevent the pressure loss, I am nervous of hurting the pump until the ground thaws. Do you have a short term solution until the ground thaws?

On 2019-02-02 by (mod) -

Kevin

If your pump is a submersible (in the well) and if there is water in the well, then a check valve in the house is probably inadequate, and even if there's a leak in well piping, when the pump turns on it ought to be able to send water to the building since it'd be self-priming.

If that's the case you'd see air in the water supply.

On 2019-02-02 by Kevin

The well is 100' deep, there is 3' of frost in the ground, would I be able to install a check valve in the house, knowing that I have a submersible pump in the well, will it hurt the life or performance of the pump until I dig up the well in the spring.

On 2019-02-02 by (mod) -

That tells us there's a leak somewhere, most-often a leaky check valve or foot valve.

You can use a local check valve with success pretty much only if the well is a shallow one - under 27 ft. deep.

On 2019-02-02 by Kevin

I have a submersible pump, when the pump shuts off at 50 psi, with no water being used, the pressure drops to 30 psi, pump starts again, I think the check valve is go in the well, can I put a check valve in my well line inside the house, to prevent the back flow of water?

On 2018-10-20 by (mod) -

Put a check valve on your pump

On 2018-10-20 by Sandy

Approximately 10 years ago I moved the gravity fed sump outside and installed a separate backflow preventer that is connected to the city water line. I am experiencing a loud whooshing sound that sounds from the interior to be coming from the main waterline. There appears to be no water leaks within the house and no toilets are running. I have the main line scoped yearly to ensure there is no debris in the lines that would cause flooding. Any suggestions as to what direction I should take?

On 2018-10-20 by (mod) - whooshing sound, pump loses prime when it turns off.

Sandy, try putting a check valve on or at your well pump.

On 2018-10-20 by Sandy

Approximately 10 years ago I moved the gravity fed sump outside and installed a separate backflow preventer that is connected to the city water line

I am experiencing a loud whooshing sound that sounds from the interior to be coming from the main waterline.

There appears to be no water leaks within the house and no toilets are running.

I have the main line scoped yearly to ensure there is no debris in the lines that would cause flooding. Any suggestions as to what direction I should take?

On 2018-08-21 by (mod) - Can I use two check valves i

Joel, deep well two-line jet pumps and some other deep water well systems use multiple check valves on the water piping, for example at every 100 ft. of vertical riser pipe.

Search this site to see. DRAINBACK VALVES and snifter valves for a better solution

On 2018-08-21 by Joel

In the winter months after pumping my well water into the tank I have to drain the water out of the filling system and well head so it wont freeze and burst the pipes, I currently have two gate valves to open to accomplish this task.

Can I use two check valves instead of opening these gate valves so as to automatically drain the water out of the filling pipes after the pump shuts off??

On 2018-08-10 by Sam

What causes the salt in our water well to turn to water

On 2018-05-15 by (mod) -

Bill,

If the valve is a backflow preventer it could be that your system is at an overpressure condition. The other comment explanation would be water hammer, or debris that's causing the valve not to close properly

On 2018-05-15 by Bill beasley

why does water run out of bottom of check valve on sprinkler system when it is not sprinkling?

On 2018-03-30 by Tony

Should a foot valve be used instead of a perforated well point?

On 2018-03-24 by (mod) -

Brandon

Often a municipal supply system may, by local codes, require two check valves or backflow preventers in series.

If you were adding one for the problem you describe you'd put it between the existing backflow preventer and the source of surge or water hammer that's causing the problem. That's probably on the house side of the existing valve.

Use the on page search box just above to find our article on

WATER HAMMER to see if that's the cause of the trouble you describe, and also check that your backflow itself is not damaged.

On 2018-03-16 by Brandon

I have a 3/4 inch R.P backfow that spitts a lil bit now and then. Now I have a spring loaded check, do i install it after the back flow or before the back flow to get it to stop spitting.

On 2018-03-07 by Maxthon

The municipal water supply into a building system is really awesome. Thank you very much.

On 2018-02-12 by (mod) -

I'm not confident to have a clear understanding of what you plan to do, but it does sound as if A check valve installed in the correct direction would certainly be opened by the pressure difference created by your water pump.

On 2018-02-10 by Hayou

i plan to install a loop in my hot water line to my kitchen. i plan to install a gravity check valve in the loop and tee it into the cold water inflow to my hot water tank. this is to prevent cold water from "back flowing" toward my kitchen. My question: Will the cold water flowing straight through the tee create enough negative pressure to open the gravity check valve?

On 2018-01-31 by (mod) -

Mary,

I recommend using the search box just above to find our article series on

HOW TO PRIME THE PUMP

You may need to use water from an outside Source such as a neighbor's garden hose or simply a bucket of clean water. if with the pump primed and the water turned off into the house you find that the pressure in the system Falls then indeed there is either a bad check valve or a leak in the well piping

On 2018-01-31 by Mary

3/4 HP jet pump. checked bladder tank, seems fine, checked switch, good connections. No prime, no reading on pressure gauge. Replaced it already. Think I have a check valve outside located vertically at shall well pipe coming from well. Gal steel to pvc looks like. going to try to get it off. 20 year old system. Have replaced well pump once. Bladder tank is original....seems fine pressure holding at 28 30/50 switch. Scared about removing what I think is the check valve. Suggestions?

On 2017-07-07 by brad

I have recently put in a new well (23 feet at 1 1/4 pipe) new pump m,tank and check valve . It all worked great for about 3 months , but now it loses prime if it sit over nite with no use , funny thing is it shows no loss of preasure at tank! very easy to prime too. all I do is crack the fill plug at the pump and it primes itself.

no leaks anywhere either! could the new check valve be bad already? and how do you explain no preasure loss at tank? very frustrating.

On 2017-06-25 by Bob

Just wanted to thank you. Your website helped me solve my well pumps short cycling problem. I thought all check valves were on the pump down in the well. After reading you web page and see the picture of the check valve on the tank 'T' I recognized my check valve. Thanks again for your time and effort.

On 2017-05-15 by (mod) -

Lynette

that's a great idea, but not a solution that I've seen. Certainly a spray on or rub on grease coating might be temporarily effective at reducing mineral salt deposition on a check valve but not a lasting one. Some manufacturers use more-permanent coatings and clog-resistant materials, but still, the root problem is in the water supply.

If your water supply contains such high minerals that in drainage it's clogging a check valve, then it is certainly clogging hot water piping and the water heater system even more rapidly;

Have your water tested for hardness, and if appropriate, you'll want to install a water softener. Use the on-page search box at the top or bottom of this page to find our article on WATER HARDNESS TEST and then on WATER SOFTENER INSTALLATION to see details.

On 2017-05-15 by Lynette O'Quinn

Is there something you can coat a check valve with so it doesn't build up calcium stay open when pump turns off?

On 2017-04-22 by (mod) -

The check valve is installed with the arrow on the valve body pointing in the direction of water flow. Beyond that, we don't know enough of your situation to offer more details. Perhaps you could give me a specific question?

On 2017-04-22 by Ritesh

Plz help me for installing check valve and it's Shep are quadrilateral shape

On 2017-02-27 by (mod) -

This doesn't sound right, Paul.

First, Your water supply system is normally under pressure - depending on whether your supply is from a residential main or a private pump and well, pressure is typically between 20 psi and 70 psi - that is way more than enough to push water up to a second floor of a home.

Second, with an upper floor faucet closed, water will have a very hard time flowing backwards out of that upper piping into a fixture below, even if building water pressure were lost - until you open the tap to let air into the line.

I would look at the piping run from source to kitchen and perhaps improve hot water temperature by insulating the piping - thus reducing the amount of heat lost as hot water flows enroute to the kitchen plumbing fixtures.

On 2017-02-27 by paul

will installing a check valve on my upstairs bathroom hot water supply line prevent water from being siphoned back down to the first floor when the hot water is turned on in the kitchen about 30 ft. away? The upstairs hot water cools in the pipes and takes a long time for the water to become hot in the kitchen. thanks.

On 2017-02-27 by (mod) - Is the second check valve just an improper bandaid solution?

Bryce:

Perhaps there is a leak in the well piping; that might allow air to be drawn into the system when the pump runs.

On 2017-02-27 by Bryce

I have a in-house single line jet pump with two sand point wells tee'd together. They are about 20' deep. I have a newer Culligan water softener system. I have twice lost the prime in the pump over the last few months as I have watched the water level in our lake drop 3-4 feet. The Culligan system wasn't using salt for the last 6 months but this turned out to be a clogged filter in their system. I've lived here about 1.5 years and the pump seemed to cycle in the middle of the night without reason so I always thought the check valves might be an issue.

I had a well company add a vertical check valve inside the house about 2' from the pump on the supply side piping thinking this would solve my priming issue. Now, I have air throughout the house from every faucet, shower, and toilet. Previous times I had to drain the system, it took maybe a day to purge all air but this is getting worse over time.

We checked the pressure tank and it is working fine. No leaks on the system side of the piping. We replaced the new check valve thinking it might not have been installed correctly and this has seemed to lessen the problem but not eliminated it.

Is the second check valve just an improper bandaid solution? Is the problem most likely the foot or tee check valves? Or is the air possibly coming from a leak in the well piping? Curious to hear your thoughts.
Thanks.

Questions & Reader Commends: Check Valves: avoid check valves on suction side of well pump for closed loop systems

For closed loop systems it is not a good idea to put check valve on suction side of pump.

Check valves for well piping systems should be placed on the discharge end of the piping. Centrifugal pumps sometimes can not open check valves on the suction side of the pump especially after repairs. - Butch 21 April 2011

I replaced a foot valve (with double clamps) in under ground cistern and it didn't hold the pressure anyway. So I add check valve front of the tank and it works just about ok - Wes

Reply:

Wes, I've seen above-ground check valves installed to defer pulling and replacing the foot valve; but Butch makes a proper and correct point.

If your system is working OK you may be fine but if you find your pump is having trouble losing prime you might go ahead and replace the valve in the cistern.

Certainly in the case of a cistern the foot valve won't be so difficult to pull as we're not talking about a deep well.

On 2017-02-27 by (mod) - single jet pump, two sand point wells teed together

Bryce:

Perhaps there is a leak in the well piping; that might allow air to be drawn into the system when the pump runs.

On 2017-02-27 05:26:02.780635 by Bryce - single jet pump, two sand point wells teed together

I have a in-house single line jet pump with two sand point wells tee'd together. They are about 20' deep.

I have a newer Culligan water softener system. I have twice lost the prime in the pump over the last few months as I have watched the water level in our lake drop 3-4 feet.

The Culligan system wasn't using salt for the last 6 months but this turned out to be a clogged filter in their system.

I've lived here about 1.5 years and the pump seemed to cycle in the middle of the night without reason so I always thought the check valves might be an issue.

I had a well company add a vertical check valve inside the house about 2' from the pump on the supply side piping thinking this would solve my priming issue.

Now, I have air throughout the house from every faucet, shower, and toilet. Previous times I had to drain the system, it took maybe a day to purge all air but this is getting worse over time.

We checked the pressure tank and it is working fine. No leaks on the system side of the piping.

We replaced the new check valve thinking it might not have been installed correctly and this has seemed to lessen the problem but not eliminated it.

Is the second check valve just an improper bandaid solution?

Is the problem most likely the foot or tee check valves? Or is the air possibly coming from a leak in the well piping? Curious to hear your thoughts.
Thanks.

On 2016-11-28 16:56:14.314426 by Darrell

I have a 1 HP jet pump on a 18' well. This pump replaced a Sears 1/2 HP pump. On both pumps, every once in awhile it just stops.

Hitting or jiggling the pump makes it start up again. I have replaced the wiring and the regulator.

Also, when it stops it does not usually trip the breaker. I have installed a regulator with a lever on it to aid in re-starting the motor when it stops.

Any suggestions?

On 2016-11-10 23:15:02.609798 by (mod)

Yes TJ either because you lose prime into the well through the foot valve (for an above-ground jet pump system) or the check valve may jam and not pass water.

On 2016-11-10 22:35:02.805950 by Tj

Can a faulty check valve prevent a pump from priming?

On 2016-10-24 23:04:03.231867 by (mod)

Georgine,

Please use the search box just above and search InspectApdeia for AIR DISCHARGE AT FIXTURES to read the common causes and cures for this problem.

On 2016-10-24 13:41:48.597816 by georgine gibbons

I have a submersible pump and I am getting alot of air sometimes, especially when the toilet is flushed. the holding tank has the right pressure and the pump is not working more often. Any idea what the problem might be?

On 2016-10-14 13:03:06.233947 by Mark

I have a residential well with a check valve near the pressure tank. Is there another check valve down the well near the well pump?

On 2016-09-28 03:12:17.372699 by (mod)

Scott:

Please search InspectApedia.com for PUMP RUNS INTERMITTENTLY to see the diagnosis and repair for this problem.

I suspect a leaky check valve or foot valve. But other causes can be present.

On 2016-09-27 00:50:45.669250 by Scott

I have a submersible pump in the well. Lately I've noticed it running intermittently. I've isolated the house at the tank, still runs every few minutes, for a short time(30 seconds or so).

So after returning water to the house I turned off power to the pump,waited 20 minutes or so and opened a faucet. Nothing there. Shouldn't I have some sort of "reserve" due to the pressure tank?

Also let me say, I never had this problem until after having an above ground pool that may have been placed above the pipe from the well to the house.

On 2016-09-21 01:25:03.905005 by (mod)

Yes that sounds right.

On 2016-09-20 02:16:32.650442 by Tammy

My house sits on a hill, at the bottom is a shut off valve, below that is another line with a shut off valve.

The well is further down a serving hill. We use this second line daily to water our animals. When we turn this line on it drains the water from the house. Should I install a check valve or backflow preventer to stop this from happening?

On 2016-08-16 01:32:53.699094 by (mod)

Watts is a perfectly fine brand.

Dual check valves means that there are two check valves connected in series. That arrangement reduces the chance of a leak or backflow.

On 2016-08-15 23:22:16.602897 by LarrY H

Wayne, you mentioned that for a well system you recommend a spring loaded check valve (any particular brand) - My well tank and tank tee are in need of replacing after about 25 years of service and

I was looking at getting a Watts 1” Brass Female In-Line Dual Check Valve Lead Free LF7R-U2-2 -

Could you explain what a dual check valve is and is it okay to use with my well system?

On 2016-07-22 20:52:52.844202 by (mod)

Wayne, if no water is running and your pump cannot reach more than 30 psi then I suspect a damaged impeller, low voltage, or a well piping leak.

About the other details in your question, I appreciate the condensation but I don't really understand the question nor think I can thus give a useful answer from e-text. If your pump is an in-well submersible unit, then there will be both wiring and a water line going down the well to the pump.

On 2016-07-21 17:06:01.412320 by wayne h

I have a submersible pump that feeds sprinkler system ... only generating 30 psi and not enough to run sprinklers (drops to 15 or less). Told x2 from well guys -- need new pump - 2K.

Thinking DIY ... question is : discharge pvc pipe (2" ?) coming from top of well cap and 90 degree back into ground - assume this feeds sprinkler system and that I DO NOT have a pitless adapter system underground.

Does the pipe coming out of top continuous all the way down to the pump ?? If so -- I assume I need to cut pipe above ground in order to get well cap off and pull pump up ?

Sorry - probably a dumb question but trying to find answer (can't find online) before I start. Thanks!

On 2016-07-19 00:35:42.617591 by Anonymous

If you're well plumber installs a foot valve on the bottom of the well fine then you won't have to keep you priming the system

On 2016-07-18 23:34:44.693301 by Dave

My mother bought a home with an above ground well pump that looks like it was newly installed.

I had an inspector come out (after the fact of course) and he mentioned that he didn't see a one-way valve preventing the system from having to be primed all the time.

There is a pipe coming out of the top (before the pump) that connects to a T connector with one branch going down the well for water and the other branching to the pump.

In order to get the system running, I have to put water in to prime the pump, but how often should I have to do this?

Shouldn't there be a check valve in the line coming up or right before the pump?

Shouldn't the open line on top be sealed, threaded maybe so there is an actual vacuum to prevent the water from going back down the well every time it shuts off?

On 2016-05-30 18:15:05.365821 by (mod)

A:

there may be some checkvalves that lack a mark but usually it's cast right into the check valve surface; for some products the "in" and "out" sides may be evident by other features. You can use the page bottom CONTACT link to send me a photo for comment.

Keep in mind that there are other brass connectors (unions and couplings) that simply make it possible to join piping and are not checkvalves.

On 2016-05-30 by Anonymous

Are chek valves clearly marked, because on my setup there is a brass connector between the line coming in and the pump, but no arrows indicating flow??

On 2016-04-09 by Anonymous

I have a water well that is more than 30 year old. Now, the water leaks to outside of house (backflow) and cause the water pressure drop.

The pump is currently in a cycle of running 20 seconds and resting 5 min even with no water usage.
I have been given 2 options from well-drilling company to fix the problem.

1. Try to pull the line and the pump/check valve out to replace them. It will cost 2k to 3k. I was told that it has a 75% chance that the pump cannot be pulled out. This will end up drilling a new well. We may not have water for 3 days or a week.

2. Drill a new well that will cost about 5K. The water outage will be short as a few hours for reconnecting the pipe to the new well.

My question is

1. What is the real chance for not be able to pull the pump out well and put a new one back in?

2. What is the best way to go?

Please advise.
Thanks, JZ

On 2016-03-29 by (mod)

Sorry I don't know what an automatic toilet sensor is; give me a proper product name, brand, model and I'll be glad to research it.

On 2016-03-29 by jose

I have automatic toilet sensor in my restrooms, will a check valve with filter helps
to prevent issues with on my fixtures.?

On 2016-02-17 by (mod)

1/250 ft

On 2016-02-17 by abid

how many check valves are install in a long water supply line i.e 30 km long supply line?

On 2016-02-06 by (mod)

How annoying, Carl. I'd double check that the valve was installed with the arrow cast into its body indicating the correct water flow direction; I'd also inspect the valve for debris.

On 2016-02-06 by Carl

My well is 100' deep the check valve at the pump stuck open. I pulled the pump installed new Simmons check valve next day it's stuck open again.Any suggestions

On 2015-12-21 by (mod)

Anon

This can be tricky to diagnose: a damaged impeller, pressure set just out of the range of the pump, or low well flow rate can all cause this trouble.

I'm not sure where you looked to see a piece of rubber - if you mean at the pressure switch, clogging the switch is certainly a problem; And we have to ask where that rubber came from; I suspect a pump or check valve o-ring or gasket part.

On 2015-12-19 by Anonymous

My submersible well pump kept running and running even though the pressure had reached approximately 40 - 50 psi.

After a very long time, it eventually hit near 60 psi and it shut off. This cycle kept happening so I replaced the pump troll and gauge. Looking through the small opening where the pump connects

, I noticed a loose disc like piece of rubber in the brass housing. I restarted the system with the new control conected and had the same result. Was that piece of rubber the check valve? And is that what's causing my problem?

On 2015-12-15 by (mod)

David,

The Apollo check valve on your boiler probably needs repair or replacement.

First: check the operating pressure of the boiler. At full operating temperature the system pressure should be under 30 psi.

When the boiler is cold, the pressure should be around 12-18 psi.

If the boiler pressure is abnormally high the problem is elsewhere - a bad water feeder or a tankless coil leaking into the boiler.

If the boiler pressures are normal then I suspect a valve seal, valve packing, or seat needs repair or replacement.

On some (not all) Apollow check valves, for excample the Bronze 30 & 30LF series Models 101T/101TLF and similar model numbers, the valve includes a packing nut that can be tightened to stop leaks at the valve stem or bonnet.

If there is no more travel to tighten the nut further then the packing needs replacement. Your valve, whose model you didn't give, is likely to be a different model and will operate differently.

Make a note of the model of your Apollo valve. With that information you can download an installation and operation manual (IOM manual) from the manufacturer.

Most likely you'll need to ask your heating service company or plumber to perform the repair.

Apollo Valves Contact Information: Apollo Valves, 1418 S. Pearl St., Pageland SC 29728, USA,
Telephone: Customer support telephone 1-704-841-6000 / 1-843-672-1644
Website: http://www.apollovalves.com/

On 2015-12-14 by David

My boiler system has an Apollo dual check valve with atmospheric port . water continues to run out of the bottom of the valve

...

Continue reading at CHECK VALVES, WATER SUPPLY, DRAINS, PUMPS or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Recommended Articles

• BACKFLOW PREVENTER VALVE, HEATING SYS
• BACKWATER VALVES, SEWER LINE
• CHECK VALVES, HEATING SYSTEM
• CHECK VALVES, WATER SUPPLY, DRAINS, PUMPS
• FLOOR DRAIN / TRAP ODORS
• SNIFTER & DRAIN BACK VALVES
• WATER FEEDER VALVES, HYDRONIC BOILER
• WATER FEEDER VALVE, STEAM
• WATER PRESSURE REDUCER / REGULATOR
• WELL PIPING FOOT VALVES

Suggested citation for this web page

CHECK VALVE FAQs-2 at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

Or see this

INDEX to RELATED ARTICLES: ARTICLE INDEX to PLUMBING VALVES

Or use the SEARCH BOX found below to Ask a Question or Search InspectApedia

Ask a Question or Search InspectApedia

Try the search box just below, or if you prefer, post a question or comment in the Comments box below and we will respond promptly.

Note: appearance of your Comment below may be delayed: if your comment contains an image, photograph, web link, or text that looks to the software as if it might be a web link, your posting will appear after it has been approved by a moderator. Apologies for the delay.

Only one image can be added per comment but you can post as many comments, and therefore images, as you like.
You will not receive a notification when a response to your question has been posted.
Please bookmark this page to make it easy for you to check back for our response.
Our Comment Box is provided by Countable Web Productions countable.ca

Citations & References

In addition to any citations in the article above, a full list is available on request.

---

ADVERTISEMENT

---