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Plumbing Foot Valve: What is a Foot Valve in Plumbing?

Plumbing foot valve with a straining basket

The plumbing foot valve prevents the reverse flow of fluids in residential, commercial, and industrial systems, including those that carry clean and wastewater. But how much do you know about its function or even how it works and its application? This post is an in-depth look at using the foot valve in plumbing systems.

What is a Foot Valve in Plumbing?

The plumbing foot valve is a one-way fitting for pumping and water transfer systems. Its primary function is backflow prevention, ensuring the proper operation of these installations.

  • For example, an underground one-way valve for a well pump keeps the pump primed, maintaining the water column in the suction pipe. As a result, it protects the pump from running dry and getting damaged.
  • In wastewater systems, the valve prevents dirty water from flowing in the reverse direction and contaminating clean water supply pipes and fixtures.

Different types of this valve are available. They vary in size, design or configuration, and other features, such as material types. The materials include brass, bronze, cast iron, stainless steel, and even plastic.

It’s important to note that these valves differ from check valves, which, despite being one-way valves, do not include filtration baskets or screens. Check valves also have connection ends on either side.

Parts of a one-way valve for plumbing systems
Parts of a one-way valve for plumbing systems

How Does a Foot Valve Work?

A foot valve ensures water or other media does not flow in the reverse direction, which is also why you can call it a one-way valve. Let’s see how that happens when using the valve in a plumbing system.

Valve Opening

  • Inside the valve is the on/off element. The element can be a poppet, ball, flapper, or a membrane.
  • The part only allows forward flow, closing the opening if it senses backflow.
  • The valve opens when flow pressure rises to reach a threshold, which is also called cracking pressure.
  • This pressure keeps the valve open during forward flow by pushing against the on/off element.

Valve Closing

  • If the pressure drops below cracking pressure, the valve quickly closes.
  • This occurs when the force of media flowing back presses against the valve’s doorway
  • In some valves, back pressure and gravitational force aid the closing action. Some use a return spring.
  • In the closed state, the on/off component rests on the seat, providing a seal that prevents media from passing through.
Cleaning a clogged foot valve
Cleaning a clogged foot valve

Can a Foot Valve be Clogged?

It can. Using a foot valve in plumbing involves installing it in water that contains impurities. Examples include inside wells, tanks, and plumbing lines that carry wastewater in residential buildings and commercial establishments.

A clogged valve cannot function as intended and may cause a reduction of flow. The dirt restricts the unobstructed passage of water or other material, causing problems in the entire system. Here is what to do if you suspect blockage.

  • If you have a clogging problem, you can restore the valve operation by cleaning it. Cleaning a dirty valve of this type should not be challenging. You only need to disassemble the various parts.
  • Some one-way valves for plumbing systems do not need you to clean them manually. Instead, they automatically remove debris from the filter using spray nozzles and water under pressure.

Note that valves for suction pipe ends come with a filtration basket attached to their open ends or inlets, unlike a check valve, which is also a one-way valve.

Replacing a foot, one-way valve for a well
Replacing a foot, one-way valve for a well

Does a foot Valve Need to be Vertical?

Not necessarily. While most plumbing foot valves work well if installed vertically, some also allow horizontal installation. These are mostly spring-operated one-way valves that do not rely on gravity to close.

However, we recommend following manufacturer directions when installing your plumbing foot, one-way valve. That’s because different types of this valve have varying installation rules, usually depending on their closing mechanisms.

Replacing a damaged foot valve
Replacing a damaged foot valve

What Happens When a Foot Valve Goes Bad?

A damaged plumbing foot valve may not function as intended. For instance, it may leak some media in the reverse direction when closed or restrict flow when open.

In addition to clogging, problems can result from wear over time. Wear mainly occurs in the delicate parts of this valve. These mainly include the rubber O-rings or plastic seats.

You can quickly fix a clogged valve of this type by cleaning it. Other issues may require professional service to replace worn or broken parts. Consider changing the valve if the components are excessively damaged.

A well-pump foot valve
A well-pump foot valve

Plumbing Foot Valve Applications

The plumbing foot or check valve is necessary to prevent the reverse flow of water in extraction or pumping systems and other pipelines where reverse flow must not happen. Example applications include water tanks, well pumps, and wastewater systems.

Water Tank Foot Valve

A water tank one-way valve ensures that water can only flow out of the tank for use and not back. You install it in the suction pipes of underground tanks. They have a filter attached to prevent dirt from damaging the suction system.

Well-Pump Foot Valve

One of the most popular uses of this valve is in well-pumping systems. Here, the valve helps keep water in the suction pipe when the pump stops running, keeping it primed and preventing damage. Like any other one-way valve, it has various options, from materials to working mechanisms.

Waste Water Foot Valve

Using the one-way valve in plumbing includes its helpful application in preventing the backflow of media in the wastewater system. Without this valve, dirty water would flow backward, contaminating clean water and causing a health risk.


The plumbing foot valve has applications in many settings, from homes to commercial and industrial installations. To find a valve for your plumbing system, choose the most suitable material based on the media type and operating conditions. You also want to select the most appropriate valve size and the best on/off mechanism for your project.

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