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 2019-04-10 by (mod) - My pump keeps running non stop,

Shola

It sounds as if there is a leak downstream of the check valve. Perhaps in piping between pump and well?

On 2019-04-09 by Shola

Hello,
My pump keeps running non stop, but if i lock the check valve at the outlet of the automatic pressure control the pump stops, if the check valve is opened the pump starts after few minutes of which i must have opened a tap in the house,

but after i close the tap the pump still keeps running until i have to go lock the check valve again before it stops.
There are no leakages in my house.

What do i do?

On 2018-12-27 1 by (mod) - check that the check valve is facing in the right direction

Eddie

How frustrating.

First check that the check valve is facing in the right direction to stop water flow - look for an arrow molded into the valve body.

If the valve is the right type, placed in the right direction, and properly oriented (some check valves have to be horizontal), and it still leaks, there may be debris in the system that's clogging the valve.

On 2018-12-27 by Eddie

Replaced check valve twice in the past month, when the pump kicks off you can hear the pressure going back through the check valve and the pump will kick back on because it lost pressure.

On 2018-08-15 by Rizer

When replacing a check valve for a shallow well irrigation pump, can I expect pressurized water blow back from the 1 1/4" being cut before the check valve? I expect some water. I just don't want a continues flow.

Any feedback is greatly appreciated before I make the crucial cut.

Thanks for your comments.

On 2018-04-22 by (mod) -

Anon

I can't guess from your note if the problem is a bad pump timer or lost prime due to another problem, but indeed if your pump loses prime when it does not run for a while I'd look for a leak in well piping or a bad foot valve.

On 2018-04-22 by Anonymous

my pumps on a timer lost Prime cuz that burn out the

Question: Check Valve Types: Which Type of Check Valve is Best for Use on Water Systems?

Just curious as to some input on the two types of check valves and is one better than the other? It would seem that the flapper type would be less restrictive than the spring type?

I have a well system and I need to replace the booster pump at the house so I want to replace the check valve to the pump suction at the same time. I currently have the spring type and it has worked ok but maybe the flapper type would be better? - Terry

Reply: Spring Loaded Check Valves are Recommended

Terry expert sources such as the Water Systems Council and many plumbers recommend spring-loaded check valves, not gravity-operated check valves and not swing-type check valves.

These recommendations have been added to our water system check valve article above.

Question: Check Valve Installation: Where Should the Check Valve be Placed on Water Supply & Well Systems

Just curious as to some input on the two types of check valves and is one better than the other? It would seem that the flapper type would be less restrictive than the spring type?

I have a well system and I need to replace the booster pump at the house so I want to replace the check valve to the pump suction at the same time. I currently have the spring type and it has worked ok but maybe the flapper type would be better? - Keith

Reply: List of Check Valve Locations on Water Supply Piping & Well Installations

Keith, some experts recommend multiple check valves while others make reasonable arguments for installing only one check valve on water systems.

But some of the confusion probably occurs because not every plumber or well installer is talking about the same installation conditions.

Take a look at the page top photo and you'll see a check valve on the incoming well line, between the jet pump and the building wall.

If we're talking about the same device and situation, and if your well pump itself is not providing an internal check valve, the usual spot for an external check valve that is above ground is just as you see in the photo.

A foot valve is installed on well piping at the bottom of the well in all shallow well installations, in deep well jet pump installations, and in some deep well submersible pump installations.

Additional check valves may be installed on well piping inside the well, within 25 ft. of the well bottom and under-water that is, below the top of the static head level of the well water, and again every 200 feet of vertical well piping in very deep well installations.

A check valve is often installed near the end of the incoming well piping right before the one line jet pump, above ground, especially if the jet pump does not have its own working internal check valve (as many do).

Question: Check Valve Installation: Which way should the check valve be installed ? What does the arrow on the check valve indicate?

The check valve I bought for a shallow well that is being dug has an arrow on it. The check valve did not come with any instructions.

Which way should the arrow run when installing it on the well pipe? I have the exact same check valve as shown in your picture above. Thanks - Susan

Reply: The arrow cast into the check valve body marks the direction of water flow through the valve

When you are installing a check valve on water supply piping, the arrow cast into the body of the valve points to the direction of flow of the water.

So, for example, if your check valve is installed on the incoming well water supply pipe between the well and the water pressure tank or water pump, the arrow on the valve would point towards the pressure tank or pump.

Question: Check Valve Installation Tips: should the check valve be horizontal or vertical?

Should spring loaded check valves be installed vertical or horizontal? - Frank

Reply:

Frank, spring loaded check valves will operate in either horizontal or vertical position - the valve relies on the spring pressure to close the valve, not gravity.

If someone is using a gravity type or swing-type check valve, the valve can also be installed vertically or horizontally provided you notice the arrow cast into the check valve body.

A gravity or swing type check valve mounted vertically presumes water is flowing "up" through the piping and the arrow on the valve body should point up.

Watch out: as we explain in the article above, well piping experts do not recommend using swing type or gravity-operated check valves. Spring-loaded check valves are recommended.

Question:

(Dec 4, 2012) Melody said:

My husband and I just replaced the check valve on our pump by adding a new one about a foot above the pump itself (it works fine).

In two days we have pulled the 60ft of pipe out of the ground just to find that it has come unglued. I have purchased three different types of PVC cement, being told everytime that this stuff is awesome and will hold anything.

We have let the cement sit and cure for hours even wrapping it with electrical tape to ensure that when put back into the well itself it would hold. I came home from work, took a shower and attempted to was a load of clothes.

Our son got in the shower and could not finish because the water pressure just dropped and no more water.

Is there a suggestion for the glue, adhesive or cement that will hold our new check valve on so we can have water? We are at our wits end and cannot afford a plumber to come fix it. I would greatly appreciate any suggestions.

Comment: PVC cement (glue) dry, set & cure time?

(Dec 8, 2012) Justin said:

Make sure you let the PVC cement set for at least 24 hours. It needs time before it can handle high pressures.

Question: water tank sizing

(Feb 16, 2014) joe said:

how to determine size of blater tank

Reply:

Hi Joe,

Please search InspectApedia for

Water Tank Size, Volume, & Requirements

and you'll see our article answering your question about how to determine the necessary size of a water pressure tank or bladder-type pressure tank.

Question: check valve prevents air backflow?

(Apr 7, 2014) Wayne said:

Will a check valve prevent the backflow of AIR ? Am suspecting that a loss of water pressure from public water supply causes backflow of water from my home, and, with a spigot open, love air back through the meter.

When pressure is restored, air is then forced back through the meter and thus causes a false reading.

Reply:

Don't know Wayne - that's one I've not heard before. I'll do some research. Generally a check valve that is water tight you'd think would resist airflow.

Question: check valve cause water hammering noise?

(Apr 7, 2014) Peter said:

I have a combination domestic city water supply that serves the domestic house and also the sprinkler system of my home. The domestic supply to the house has a pressure regulator to control the psi at 50 psi. The sprinkler supply has an in line check valve installed. I have recently started to get water hammer noise on the sprinkler supply side of my service. The water hammer noise is intermittent and occurs at all hours of the day, even though no water is being used in the house. If I close the valve to the sprinkler, it stops the water hammering sounds. Could the check valve to the sprinkler be faulty and is causing the water hammering?

Reply:

Peter that sounds like a very reasonable guess. It's sudden stopping of water flow that would be the initial cause of water hammer. Try changing the check valve and let us know the result - what you report will help others.

See WATER HAMMER NOISE DIAGNOSE & CURE

Question: check valve location on rootop water tank; when are supply valves installed?

(June 28, 2014) John said:

Hi,
I have a gravity water tank roof top on my house-Water is pumped up by the city when working ok-When the water (municipal) is not working I use the roof tank,

Where should a check valve be installed at?

(July 1, 2014) Kyle said:

Supply control valves for bathroom sinks and toilets are installed during what stage

Reply:

Kyle the supply valves, if they are provided (which I recommend) are installed at the time of connection of the fixtures to the supply piping or sooner.

For example one might install the rough-in plumbing, then install supply valves at fixture locations throughout the building, leaving them in closed position.

That allows water to be turned on and used at some building locations before fixtures have been installed throughout.

The alternative of soldering a cap on the un-connected supply pipes is less attractive since later to connect up those supplies to fixtures building water has to be turned off.

Question: Franklin J class Series V pump runs but doesn't pump water

(Aug 14, 2014) Barry said:

I have a franklin j-class series v pump that is constantly running and not pumping any water. The pump is only three months old. It is installed in a large holding tank that is part of my water treatment system.

The problem started after I drained the tank to clean it. when I fillled the tank back up, I turned on the power, and the pump ran constanty without pumping any water. I believe this pump has a check valve...but not sure how to get it to start pumping water. Any help would be greatly appreciated.

Reply:

Barry

Watch out - leaving a pump running dry can damage it.

You may need to see our procedure PRIME the PUMP, HOW TO

Question: pump runs but very little water pressure

Glenn said:

We bought this place 1 year ago the former owners had to put in a new pump, and tank.
The pump is working I can feel it and hear it hum.
The gauge reads 10 psi when I turn the water off to the house and the out faucet the presser starts to build but when I open valves psi drops.
Any thing I need to check?

Reply:

Glenn,

It sounds as if you need to look through our diagnostics on causes of lost water pressure. At the ARTICLE INDEX at the end of this article click on the article titled

WATER PRESSURE LOSS DIAGNOSIS & REPAIR

Question:

(Sept 17, 2014) Glenn said:
We bought this place 1 year ago the former owners had to put in a new pump, and tank.
The pump is working I can feel it and hear it hum.
The gauge reads 10 psi when I turn the water off to the house and the out faucet the presser starts to build but when I open valves psi drops.
Any thing I need to check?

Reply:

Glenn,

It sounds as if you need to look through our diagnostics on causes of lost water pressure. At the ARTICLE INDEX at the end of this article click on the article titled

WATER PRESSURE LOSS DIAGNOSIS & REPAIR

Question: can a backflow preventer valve failure prevent heat from operating in a building?

(Nov 4, 2014) PHILIP said:

If the water back fill preventor valve is not working can you get heat?

Reply:

Yes and no. If the backfill valve is blocked so as to keep a boiler from having sufficient water then a drop in water level might trigger a low water cutoff safety valve - that would turn off heat.

Question: how to get water out of the well piping to avoid frozen water lines

(Nov 4, 2014) Anonymous said:
We winterized our home last year and when we opened this spring, the water line from the well had burst. This year, we want to take the water out of the supply line without opening the foot valve....how do we do this. We tried a pump but it pumps 128 gallons/hour. We tried a hose and tried to suck it out, but nothing happened....how can we lower the water in the supply line without opening the foot valve. Thanks for your help.

the well is approx. 75' from the building and the well is approx. 30' deep. forgot to say that

all we want to do is take out enough water so the level of the water is below the ground so it doesn't freeze

Reply:

Anon I don't think you will have much success with the approach you describe. The foot valve acts as a check valve that prevents you from pushing air back down the piping to remove water from the well piping.
And you'd hardly be able to pump water *out* of the well piping unless you first ran the well dry.

Traditionally we protect well piping from freezing by putting it below the frost line -
see

Well Pits disussed at inspectapedia.com/water/Well_Pits.php

and see Pitless Adapters described at

inspectapedia.com/water/Pitless_Adapter.php

I did participate with a friend Stu T. who designed a freeze-proof water supply system for picking up water from a lake: he pumps air into the lake water line at sufficient pressure to push water back out into the lake to protect piping to a depth greater than the lake's freeze level. But as I said, for an in-well pipe with a conventional foot valve I'm doubtful of that approach.

Question:

(Nov 10, 2014) richard johnson said:
what is the service life of check valve on a municipal water system

Question: clicking sounds from water pump control

(Nov 22, 2014) lois said:
Every 20 minutes to the minute there is a click, then 2 minutes after (you hear water filling my tank), and then two minutes
after it shuts off - this happens every twenty minutes - what could be connected to my well/pump to make this happen,

Reply:

Lois, please see the following diagnostic procedure for intermittent cycling of a well pump

inspectapedia.com/water/Intermittent-Water-Pump-Cycling.php

Question:

(Nov 29, 2014) Joyce Edwards said:
We just replaced the booster pumps in our condo building and backflow preventer. We just added a shut off valve and now we have the pumps working constantly and we are hearing a lot of noise. Residents are complaining. The engineer says it's the valve's fault and the plumber came in and checked and said it is the pumps. What should we do. This already has cost a lot of money .
Thanks
Joyce. A Board member and in need of suggestions. We are. In a city.

Reply:

Joyce

Let's start by stopping the finger pointing between the engineer and the plumber. A simple mechanic's stethoscope touched to the outside of the backflow preventer and to the pumps can confirm where the noise is originating.

Keep us posted.

Question: what horsepower pump is better and why does 4HP = 6HP

4 December 2014 Anon asked:

What size water pump is best? One plumber said that I need a 4 horsepower pump, another told me that I need a 6 horsepower pump, the first plumber said his 4 hp pump had the same capacity as the 6 hp model.
I'm confused. - Anon

Reply:

Not meaning to sound glib, why would 4hp = 6 HP? One would need the application details such as lift height and flow rate and piping specs to compare with the pump manufacture's recommendations.

I understand that pump technologies may make the actual lift or flow rate capacities of pumps vary with some independence of horsepower, electricity usage, and pump life but still we need more specifics to make sense out of equality claims among pump models.

Question:

(Dec 11, 2014) PLN SARMA said:
I am having overhead tank at 45ft over which Motor Pump is installed with Timer to water plants on Terrace at 36' and also plants on Ground under Drip System. There is a foot valve of Jet Type at the end of Suction Pipe.
Water continues to flow even after Pump stops under Syphon Principle under gravitational Pull and thus empties my water Tank and water is wasted.
How to arrest this phenomena and conserve precious water. What Flaw is there in the Design. Is there any valve that can prevent drawing water once the Pump stops

Reply:

Sounds like you need a working check valve where none is installed, or mor elikely to replace a failed foot valve.

Question: diagnose frozen well lines: role of the snifter valve

19 Feb 2015 Dave Z said:
I am trying to diagnose why my well line intake has frozen twice in the last year. I have a submersible pump well system and at the inlet end of my air over water pressure tank, I have a check valve installed along with a snifter valve on the inlet side of the check valve. As I understand it, once the pump completes its cycle and the check valve closes, the snifter valve is supposed to allow air to bleed into the pipe, so the excess water drains back to the well. Foe the line to freeze, I suppose the water has not been able to drain back , or perhaps my check valve is allowing water to leak back to the well slowly and its freezing up? I know I can add a heat trace line to prevent freezing , but I wonder if anyone has suggestions as to what may be faulty in the first place?

Reply:

Dave

As we discussed in another exchange, the Snifter Valve injects air into the water piping from its location above ground close to the bottom of the water tank and thus allows water to drain out of the well piping (or lake water piping) back into the well at the drain-back valve located in the well (or in the lake) at each pump-on/off cycle - in order to keep frost-exposed water piping from freezing between the water source (well or deeper in the lake) and the building.

This well pipe freeze protection system works with an AVC on the tank, a snifter valve - a low-pressure schrader valve (typically on the well line close to the pressure tank) that allows air into the well piping and a drain back valve (located on a tee in the well piping in the well) so that well water can drain back into the well or other water source (a lake for example).

If the drain back valve is clogged or if the snifter valve is not allowing air into the piping your frost-exposed well pipes are at risk of freezing. We give more diagnostic details in our snifter, drain back, and well pipe freeze protection article:

See SNIFTER & DRAIN BACK VALVES for details of how this system works.

Question: iron clogged check valves led to burned up well pump?

25 Feb 2015 JD said:
My well pump was replaced 15 months ago and burned out last week. The installer thought the problem was due to iron in the water clogging the check valves. Besides the check valve that comes in the pump there is a gate type check valve and an additional spring check valve above the pump. There is also a 6 GPM reducer in addition to the 3 check valves. Does this seem excessive?

Reply:

JD

If your installer can show you a clogged check valve s/he'd be on reasonable ground, as if a pump can't push water into the pressure tank to satisfy the pressure control switch it'd keep running and risk burnout.

Flow reducers have a different purpose: to slow the flow rate out of the well in an effort to avoid burning up a pump in a well that has a slow recovery or flow rate into the well bore. The presence of that device on your system makes me suspect that the root problem is poor well flow rate; if the pump gets ahead of the flow rate into the well bore it can indeed burn up unless it's protected.

InspectApedia has more advice about well pump protection devices:

See WATER PUMP PROTECTION SWITCH

Comment: water hammer and check valves

(May 26, 2015) Anonymous said:
you are wright about that. had a swing gate before the pressure tank . water hammer fractured the tank tee

Question: check valves on water supply to fire fighting pumps

2 July 2015 Vincent Iweze said:
Can a check valve be mounted directly on a foot valve for negative suction in fire fighting pump installation

Reply:

VIncent

The foot valve is itself a check valve.

For deep wells (hundreds of feet) the well pump manufacturer will usually recommend additional check valves at intervals in the riser pipe.

But there are special requirements for check valves on water supply systems and pump systems used fire fighting applications.

Take a look at NFPA:20 available from nfpa.org:

NFPA 20 protects life and property by providing requirements for the selection and installation of pumps to ensure that systems will work as intended to deliver adequate and reliable water supplies in a fire emergency.

The following excerpt is quoted from an article by Milosh Puchovsky in CSE Magazine in 2012:

Certain devices in the suction piping can cause an undesirable degree of uneven flow and turbulence, and impede pump operation and performance.

NFPA 20 currently states that within 50 ft of the pump suction flange, no valve other than a listed outside stem and yoke (OS&Y) valve can be installed in the suction piping.

This provision was revised to clarify that no “control” valve other than a listed OS&Y valve is to be installed within 50 ft.

The provision was further revised to specifically address backflow devices.

These changes provide for better consistency with other provisions of the standard and clarify the intent of the requirement, which is to restrict only the use of butterfly valves, and allow the installation of OS&Y gate valves, check valves, and backflow devices in the suction piping.

Note, however, that the installation of check valves and backflow devices in the suction piping is only permitted where such devices are required by other standards or by the AHJ.

Where a check valve or backflow prevention device is required upstream of the fire pump suction, NFPA requires the device to be a minimum of 10 pipe diameters upstream of the pump suction flange. - Puchovsky, Milosh, P.E., FSFPE, " NFPA 20: Changes to the standard on fire pumps - Regardless of whether the 2013 edition of NFPA 20 will be applicable to your next project, fire protection engineers need to be aware of the changes to the standard." - CSE Magazine - By Milosh Puchovsky, PE, FSFPE, Worcester Polytechnic Institute, Worcester, Mass 11/15/2012

Question: pump losing prime, I suspect the backflow preventer. How can I test that?

(July 4, 2015) Marty said:
I have shallow well so my pump is located in the crawl of my cottage. Recently we have been losing the prime. I'm guessing it's the backflow preventer. It's located between the well and pump. Is there a better location? How can I test to see if it's working.

Reply:

Marty turn off water into the Home. If the pump still loses prime then the leak is between pump and bottom of the well pipe;

The check valve may be a foot valve at the bottom of the well piping - if yours is a jet pump;

Question: problem with intermittent water loss

Nov 6, 2015) Anonymous said:
I've been using your website for the past month or so to figure out what is going on with my water. Thanks for doing this. I have been experiencing intermittent water loss. I have a private well. The water will run for a few minutes (not always the same amount of time) and then the water flow actually stops completely on the water fixtures furthest from the water tank. After about 1-2 seconds it will turn back on. The pressure is normal at all others times. First thing is I changed the house water filter...a few times now. Then I changed the pressure switch. Today I put in a new water pressure tank even though the other one had no typical symptoms. (It was 11 years old, so I figured that must be it) That did not solve the problem. The fact that water pressure is normal other than these hiccups makes me think (and hope) it is not the well pump. The only thing it seem sit could be now is something wrong with the house hold filter assembly which is a very basic cartridge type. Or else the water heater is allowing air into the system. Water heater seems fine and is not leaking even form the pressure relief. I am a DIYer and not a plumber, but it seems like some "backpressure" disrupts the flow and then it starts again. Thanks again.

Reply:

Anon,

There is this diagnostic article on intermittent water pressure loss: WATER PRESSURE INTERMITTENT LOSS at inspectapedia.com/water/Water_Pressure_Comes_Goes.php

You can help me out by telling me if you never found that information and how you searched InspectApedia so I can make it easier to find.

Intermittent loss of water pressure or all water flow won't normally be caused by something that itself is fairly constant in behavior such as a water filter.

A sticking or bad switch could be at fault as can an overheating pump motor that goes off on thermal re-set if the water system is short-cycling or if the well water is so low that the pump runs too long without reaching the cutout pressure. So your reasoning is not bad: a bad pressure tank could cause short cycling that overheats the pump that causes the pump to shut off.

When you have water loss at the most-distant (probably highest) fixtures from the water tank I suspect you're seeing very low water pressure that just can't make it up to the high fixtures; that in turn says the pump may be off or the pump may be running but unable to get water into the building - perhaps because the well flow rate is poor and the pump, if protected by a tailpiece, keeps running but stops sending up water. Or much water.

An experienced well plumber or electrician might monitor the current draw on your pump circuit to look for signs of a motor that is drawing high current (perhaps a failing motor) or too low current (perhaps running dry).

Start by watching the pressure switch and gauge: does the pressure continue to drop when the pump is off? That suggests a bad foot valve and loss of prime - that can on occasion be intermittent and occasionally self-recovering.

Next note if the pump is able to reach the cut-out pressure at every on-cycle. If not either we've got a bad pump, bad impeller in the pump, low water flow into the well, or maybe low voltage, or less often a leak in well piping.

Among those clues ask which clue or condition could possibly come and go (like level of water in the well or flow rate or a sticking check valve or a loose wire or varying supply voltage)_

vs which conditions would always be present (like a leak in well piping or a bad pump impeller)

(Nov 6, 2015) Anonymous said:
It me again...Anonymous...I forgot to ask, could it be the one way check valve?

Thanks

Reply:

A check valve, if it's sticking open gives the same trouble as a bad foot valve: you'll lose well prime - a problem if the well pump is an above-ground unit.

(Nov 7, 2015) Anonymous said:
Thanks for getting back to me. I am taking a break from the plumbing business for a little bit (have to return to my day job).

I think the next step will be to call someone to check out the well. Don't know if you care but I'll let you know how it turns out. As a follow up, you asked if I had found that article on troubleshooting.

Yes I did. I think my particular problem was hard to fit into a category because the water comes right back to normal pressure, there is no gradual loss and the recovery is a full recovery.

This is a great service you offer. Thanks for doing it.

Reply:

Anon: yes please keep me posted: what we learn may help other readers.

The fact that water flow stops completely and then suddenly returns to normal pressure suggests that a valve somewhere in the system is broken and sticking open or shut.

...

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 CHECK VALVE FAQs-2 - more-recent questions and answers about check valves on water systems

Or see these

Recommended Articles

• BACKFLOW PREVENTER VALVE, HEATING SYS
• BACKWATER VALVES, SEWER LINE
• CHECK VALVES, HEATING SYSTEM
• CHECK VALVES, WATER SUPPLY, DRAINS, PUMPS
  • BACKFLOW PREVENTERS on WATER PIPES
  • BACKFLOW PREVENTER, HEATER WATER FEEDER
  • BACKFLOW PREVENTER VALVES on HEATING BOILERS
  • CHECK VALVES on DRAINS, SEWAGE PUMPS, SUMP PUMPS
  • CHECK VALVES on WATER PIPING & PUMPS & WELLS
  • MUILTIPLE CHECK VALVES OK?
• 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 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

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