Check Valve vs Foot Valve: Key Differences, Applications & How to Choose

A check valve stops backflow anywhere in a pipeline, while a foot valve is a check valve with a built-in strainer, fitted at the bottom of a pump suction line to keep the pump primed. Every foot valve is a check valve, but not every check valve can work as a foot valve. This guide explains how the two differ, where each belongs, and how to choose between them for PVC-U/C (UPVC) piping systems.

Check Valve vs Foot Valve at a Glance

What Is a Check Valve?

A check valve, also called a non-return or one-way valve, lets fluid pass in one direction only. It needs no handle or motor: the flow itself opens it, and reverse pressure, gravity or a spring closes it.

How a Check Valve Works

When upstream pressure exceeds downstream pressure, the internal ball, disc or poppet lifts off its seat. When flow stops or reverses, it seats again and seals. The minimum upstream pressure needed to open it is called the cracking pressure, and it varies by design.

Common Types of Check Valves

• Swing check valve

• Single union check valve

• True union check valve

What Is a Foot Valve?

A foot valve is a check valve designed for the intake end of a pump suction line. Its job is to hold water in the pipe when the pump stops, so the pump stays primed and does not run dry on restart.

Key Components: Check Mechanism and Strainer

A foot valve combines a one-way sealing element with a strainer screen on the inlet. The strainer keeps leaves, sand and small stones out of the pump. It opens at a low pressure so the pump does not need to work hard to lift the water.

Common Types of Foot Valves

• Swing foot valve

• Single union foot valve

Check Valve vs Foot Valve: 7 Key Differences

1. Function

A check valve only prevents backflow. A foot valve prevents backflow and, more importantly, keeps the pump primed.

2. Installation Location

A check valve can sit anywhere backflow must be stopped, such as the pump discharge or a branch line. A foot valve always goes at the bottom of the suction line.

3. Built-in Strainer

A foot valve includes a strainer. A standard check valve has none and expects a clean fluid.

4. Opening (Cracking) Pressure

A foot valve opens with very little pressure so the pump can draw water up easily. A spring-loaded check valve needs enough pressure to overcome the spring.

5. Flow Direction and Orientation

A foot valve passes flow upward from the source into the pump. A check valve works in horizontal or vertical pipes, depending on its design, as long as the arrow matches the flow.

6. Working Environment

A foot valve stays submerged. A check valve may run dry or wet.

7. Maintenance

Foot valve strainers clog and must be cleaned. Check valves need little attention unless a seal wears or debris holds the seat open.

Can a Check Valve Replace a Foot Valve?

Usually not. A plain check valve at the bottom of a suction line lacks a strainer, so debris can reach the pump, and its higher opening pressure can make priming harder. It can work only where the fluid is clean and the valve opens easily under suction. The reverse also fails: a foot valve on a pump discharge line adds a strainer where none is needed.

Where to Use Each Valve

Foot Valve Applications

Foot valves belong wherever a pump draws from a lower source: wells, ponds and rivers for irrigation, storage tanks and cisterns, sump pits, and aquaculture water intakes. The strainer protects the pump in debris-heavy water.

Check Valve Applications

Check valves protect pumps and pipes on discharge lines, prevent backflow in water treatment and chemical dosing lines, and keep flow one-way in branch circuits and wastewater lines.

Why Choose PVC-U/C Check Valves and Foot Valves?

• Corrosion resistance: PVC-U/C does not rust, which suits water treatment, irrigation and many chemical lines.

• Lighter and more economical than brass or stainless steel valves of the same size.

• Know the limits: PVC-U/C is not intended for high-temperature service, so check your medium and temperature against the valve rating.

How to Choose the Right Valve: Selection Checklist

Fluid Type and Debris Level

If the water carries sand, leaves or sediment and the valve sits at a pump inlet, choose a foot valve. For clean fluid inside a pipeline, a check valve is enough.

Pump Type and Suction Lift

Pumps that lift water from below need a foot valve to stay primed. Pumps with flooded suction or discharge protection needs call for a check valve.

Size and Connection

Match the valve to your pipe size and joint type: socket (solvent cement), threaded or flanged.

Standards

Confirm the dimensional standard your project uses, such as DIN, ASTM, JIS or GB.

Pressure Rating and Seal Material

Compare the working pressure with your system, and choose EPDM or FPM seals to suit the fluid.

Installation Tips

Foot Valve Installation

• Keep the valve fully submerged so the pump never draws air.

• Hold it off the bottom of the tank or well to avoid pulling in sediment.

• Make the connection airtight, since a loose joint lets air in and the pump loses prime.

Check Valve Installation

• Follow the flow arrow on the body; a reversed valve blocks flow.

• Confirm the allowed orientation for the type, because swing check valves need the hinge horizontal.

Troubleshooting Common Problems

• Pump loses prime: check for suction-line air leaks, a clogged strainer, or a seat that is not sealing.

• Low flow or cavitation: clean the foot valve strainer.

• Banging at shutdown (water hammer): a swing check valve may be closing too abruptly; consider a spring-loaded type.

• Leakage: inspect the seal ring and seat for wear or trapped debris.

FAQ

What is the main difference between a check valve and a foot valve?

A foot valve is a check valve with a built-in strainer, made for the bottom of a pump suction line. A check valve is a general one-way valve used anywhere in the system.

Can I use a check valve instead of a foot valve?

Only with clean fluid and a valve that opens easily under suction. Otherwise debris can reach the pump and priming may fail.

Do I need both a foot valve and a check valve on a pump?

Often yes. The foot valve keeps the suction line full, and a check valve on the discharge side protects the pump from reverse flow.

Why does my pump lose prime with a foot valve installed?

The usual causes are air leaks in the suction line, debris holding the seat open, or a worn seal.

Are PVC foot valves suitable for chemical use?

PVC-U/C resists many chemicals, but compatibility depends on the fluid, concentration and temperature. Check these against the seal material (EPDM or FPM) before choosing.

Conclusion: Which Valve Do You Need?

Choose a foot valve at a pump inlet that lifts water from below, where you need to keep prime and filter debris. Choose a check valve anywhere else you must stop reverse flow. Many pumping systems use both.

Huasheng supplies PVC-U/C check valves and foot valves in socket, threaded and flanged versions to DIN, ASTM, JIS and GB standards. Send us your medium, pipe size and pump details, and our team will recommend the right valve. Request a quote.