Water System Check Valve FAQs

Index to all Q&A on Water System Backflow Preventers & Check Valves

Check Valve Type FAQs

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.

What's a dual check valve and what is a good brand? Watts?

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 2016-08-15 by LarrY H

Answer 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.

What kind of check valves are used 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

Check Valve Location FAQs

Check Valve Location: 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).

Can I install a check valve at the water tank if the foot valve isn't working?

Is there a disadvantage to installing a check valve at the pressure tank if the check valve on the submersible pump is not working? On 2015-04-11 by walt

Answer by (mod) - some pumps don't want multiple check valves

Walt

That's a common repair effort that might work;

some pump manufacturers warn that multiple check valves in the system can cause malfunctions but that advice is inconsistent with standard advice for deep well submersible pump installations: there we're advised to install an additional check valve for every 150 feet of lift. So IMO bottom line, try it.

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.

Immediately after pump shuts off at 50 it drops to 30 and then refills: Where will I find the check valves

I have lots of water but immediately after pump shuts off at 50 it drops to 30 and then the pump comes back on and refills my tank; k

this happens a few times every minute. And no water is running anywhere in the house. Where's the bad check valve? Or is this a bad bladder? On 2016-11-08 by john

by (mod) pressure drops after pump turns off - there is a leak to find and fix: here are common check valve locations

John:

Check for a leak in well piping or foot valve if you can by shutting off a valve between well and pump (don't let the pump keep running or it'll be damaged).

If the pressure drops then there's a leak on the house side. If pressure doesn't drop but does when you open the valve again then there's a leak in well piping or foot valve.

Depending on just what type of pump you have installed there may be a check valve in the pump itself ( a one line or two line above ground jet pump)

and there may also be a check valve in the well (a foot valve at the bottom of the water pick-up line)

and for deep wells using a submersible pump or a deep well using a 2-line jet pump, if the water pick up is more than 200 feet down in the well there may be additiona check valves on the vertical well pipe in the well.

Check valve location on rootop water tank; when are supply valves installed?

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? (June 28, 2014) John

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.

Can I use a check valve upstairs to prevent hot water from siphoing back downtairs?

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 paul

by (mod) - no; here's how your water system works

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.

Check Valve Installation FAQs

Check Valve Installation: Which direction 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.

How do I know which direction to face the check valve on a water line?

Are check 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 2016-05-30 by Anonymous

Answer by (mod)

Anon: there may be some checkv alves 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.

If you look into the valve body before it's installed you'll see the hinged flapper has a hinge at its upper end and you can see from the angle of the valve flapper the direftion into which it will open. Install the valve so that the valve opens towards the "downstream" direction of water flow - away from the water source

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.

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.

How many check valves are needed on a long water supply line?

How many check valves are install in a long water supply line i.e 30 km long supply line? On 2016-02-17 by abid

Answer by (mod)

Typical manufacturer recommendations are to put a check valve for each 200 to 250 feet of vertical well pipe rise.

ON long horizontal runs such as your 30 km line you should note the changes in elevation but the distance between check valves may of course be much greater as it's not likely to be straight up or down changes in elevation.

Will an additional check valve at the water tank outlet prevent the pump from losing prime?

I am installing an indoor water storage tank and using a jet well pump (with a preinstalled check valve.)

Am I able to place an inline CHECK Valve at the base of the storage tank outlet to keep from losing prime, rather than run plumbing to the storage tank at the top and attaching a foot valve to a suction pipe? Thanks in advance! On 2019-02-05 by SSG

by (mod) - no, that's not the right place

That does not sound correct to me. You want your check valve to be on the line between the pump and the well.

by SSG

Thanks for the quick reply. The pump has a prebuilt check valve at the suction line.

What I am thinking is adding a second check valve at the base of the storage unit to prevent the backflow of water in the line to the tank, and still keep prime. I've added a picture from this site that shows an example of my thoughts. Thanks again!

by (mod) -

I don't understand what that would buy you. The water pressure tank connects to building supply piping and keeps it pressurized. There would not normally be backflow from building supply piping into the tank.

If your well piping leaks and the pump's check valve leaks the pump is still going to lose prime.

Check Valve Damage & Failure FAQs

Plumber says iron in water clogged a check valve and burned up our pump

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? On 2015-02-25 by JD

Answer by (mod) -

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

Check valve at the well pump is stuck open

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 2016-02-06 by Carl

Suggestions 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. Debris or mud can clog or jam a check valve.

Check valve cause water hammering noise? Water Hammer Damages Check Valve!

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? (Apr 7, 2014) Peter

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

Water hammer broke the swing gate in our check valve

You are right about that. had a swing gate before the pressure tank . water hammer fractured the tank tee (May 26, 2015) Anonymous

Iron clogged check valves led to burned up well pump?

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? 25 Feb 2015 JD

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

How do I avoid minerals in hard water clogging the check valve?

Is there something you can coat a check valve with so it doesn't build up calcium stay open when pump turns off? On 2017-05-15 by Lynette O'Quinn

Suggestion 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.

Check Valve Testing FAQs

Pump losing prime, I suspect the backflow preventer. How can I test that?

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. (July 4, 2015) Marty

Reply: turn off pump; turn off water into building; watch for pressure drop in the system.

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;