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A foot valve and a check valve both stop water from flowing backward, but they are made for different jobs. A foot valve is usually the better choice at the submerged end of a suction line, while a regular check valve is better for many other places in a water system.
For a rainwater pump pulling from a tank, cistern, pond, or other water source, a foot valve can help keep the suction line full between pump cycles. That makes it easier for many surface pumps to stay primed.
A standard check valve is more flexible. It can be installed in pressure lines, pump discharge lines, and other plumbing where you only need to prevent reverse flow.
Foot Valve vs. Check Valve at a Glance
| Feature | Foot Valve | Check Valve |
|---|---|---|
| Stops reverse flow | Yes | Yes |
| Usually installed underwater | Yes | Not necessarily |
| Common location | End of pump suction line | Many locations in plumbing |
| Built-in screen or strainer | Usually | Usually not |
| Helps maintain pump prime | Yes | Can, depending on location |
| Best for pressure-side plumbing | Usually no | Yes |
| Needs access for cleaning | Yes | Yes |
The main difference is not how they stop reverse flow. It is where they are designed to work.
What Is a Foot Valve?
A foot valve is a type of check valve installed at or near the bottom end of a pump's suction pipe.
It allows water to travel toward the pump but closes when water tries to flow backward.
Most foot valves also have a screen or strainer around the inlet. The screen helps keep leaves, insects, gravel, and larger debris from entering the suction line.
For example, imagine a surface pump pulling rainwater from a cistern. When the pump shuts off, gravity may try to drain the suction pipe back into the tank. A working foot valve closes and helps keep that pipe full of water.
Keeping the suction line full matters because many surface pumps cannot pump air effectively. They need water in the pump housing and suction line before they can operate correctly. This is called being primed.
What Is a Check Valve?
A check valve is a one-way valve that allows water to move in one direction while blocking flow in the opposite direction.
Unlike a foot valve, it does not have to sit at the end of a suction pipe.
Check valves may be used:
- After a pump
- In irrigation plumbing
- Between tanks
- In pressure systems
- On certain suction lines
- Anywhere reverse flow needs to be controlled
There are several check-valve designs, including spring-loaded, swing, and other configurations. The correct type depends on the system's flow, pressure, orientation, and water quality.
When a Foot Valve Is Better
A foot valve is usually the better choice when a surface pump draws water upward through a suction line.
A common setup looks like this:
Tank → foot valve → suction pipe → pump
When the pump runs, water enters through the foot valve and travels toward the pump. When the pump stops, the valve closes.
This arrangement can help prevent the suction line from draining.
Rainwater tanks and cisterns
A foot valve can be useful when a pump sits outside or above a rainwater tank.
Without a working valve, the water in the suction pipe may drain backward after the pump shuts off. The pump may then lose its prime.
The next time it starts, it may struggle to pull water.
Shallow wells and similar water sources
Foot valves have also traditionally been used on suction pipes extending into shallow wells and other water sources.
The same basic principle applies: keep water in the suction line when the pump is not running.
When a Regular Check Valve Is Better
Choose a standard check valve when you need to stop reverse flow somewhere other than the submerged inlet of a suction pipe.
For example, a check valve may be used on the discharge side of a pump to reduce water flowing backward through the pump after shutdown.
A common arrangement might be:
Tank → pump → check valve → irrigation system
The exact location depends on the pump design and plumbing layout.
A check valve is also usually easier to fit into above-ground plumbing because you can choose a valve style made for the pipe size, pressure, installation direction, and service conditions.
Can You Use a Check Valve Instead of a Foot Valve?
Sometimes, but the two are not automatically interchangeable.
A regular check valve installed in the suction line may keep water from draining backward. However, it usually does not provide the screened inlet that a foot valve provides.
If the open suction pipe sits inside a rainwater tank, debris could enter the pipe unless you provide suitable inlet screening separately.
Valve location also matters.
A valve installed farther from the water source leaves more suction piping that may drain, leak air, or become difficult to prime.
For many traditional surface-pump installations, putting a foot valve near the submerged end of the suction line is the simpler arrangement.
Always follow the pump manufacturer's plumbing instructions. Some pumps use different suction configurations or include their own non-return components.
Can You Use a Foot Valve Instead of a Check Valve?
Not everywhere.
A foot valve is designed mainly as an inlet valve for a suction line. Its strainer and construction may make it unsuitable or unnecessary in a pump discharge line.
If you simply need to stop pressurized water from flowing backward through a pipe, a check valve designed for that pressure and installation is usually the better choice.
Why Valve Size Matters
The valve should match the plumbing and the flow requirements of the pump.
A valve that is too restrictive can reduce the amount of water reaching the pump.
Check comparing check valve options to verify how this decision affects connected system stages.
This is especially important on the suction side.
Surface pumps work best when suction resistance is kept low. Long pipes, small pipe diameters, excessive fittings, clogged strainers, and restrictive valves can all make it harder for the pump to draw water.
Do not choose a foot valve only because its threaded connection can be adapted to your pipe. Check the pump manufacturer's recommended suction-pipe size and valve arrangement.
Suction Lift Matters Too
A foot valve can help maintain prime, but it cannot overcome an unsuitable pump layout.
A surface pump must create enough suction to lift water from the source to the pump.
The vertical distance between the water surface and the pump is often called suction lift.
As that distance increases, pumping becomes harder. Pipe friction and fittings add more resistance.
No foot valve can make a surface pump reliably lift water beyond the pump's operating limits.
If your rainwater tank is far below the pump or the suction pipe is unusually long, review the pump specifications before changing valves.
Keep the Foot Valve Off the Tank Bottom
A foot valve should normally not rest directly on the bottom of a rainwater tank.
Sediment often collects there.
Placing the inlet in that sediment can clog the foot valve screen and send more dirt toward the pump.
The inlet should be positioned so it stays underwater during normal operation while avoiding settled debris.
Some rainwater systems use a floating intake instead. A floating intake draws water from below the water surface rather than from the bottom of the tank. Depending on the system design, it may use its own screened intake and non-return arrangement.
Watch for Air Leaks
A foot valve may appear to be failing when the real problem is an air leak in the suction plumbing.
Possible leak points include:
- Threaded fittings
- Pipe joints
- Hose connections
- Pump inlet connections
- Cracked suction hose
- Valve connections
A suction-side leak may pull air into the pipe without visibly leaking much water.
That air can cause poor priming, reduced flow, noisy operation, or loss of pump performance.
If a pump repeatedly loses prime, inspect the whole suction side rather than replacing the foot valve automatically.
Foot Valves Need Cleaning
The strainer that makes a foot valve useful can also become clogged.
Rainwater tanks may contain small amounts of:
- Roof grit
- Organic debris
- Insects
- Sediment
- Biofilm
A blocked screen restricts water entering the pump.
If pump flow gradually falls, inspect accessible strainers and intake components as part of troubleshooting.
Design the system so the valve can be reached without dangerous tank entry. Do not enter a cistern or other confined tank to retrieve or service a valve unless the work is being handled under appropriate confined-space procedures by qualified people.
Check Valves Need Maintenance Too
Regular check valves can also fail.
Debris may keep the internal sealing surface from closing completely. Springs can weaken in some valve designs, and seals can wear.
Possible signs of a check-valve problem include:
- Water flowing backward after pump shutdown
- Pressure falling unusually quickly
- Frequent pump cycling
- Loss of prime in some suction configurations
These symptoms can have several causes, so inspect the overall system before assuming the valve is responsible.
Which Is Better for a Rainwater Pump?
For a surface pump pulling water through a submerged suction pipe, a foot valve is often the better choice.
For a pump discharge line or other pressurized plumbing, a standard check valve is generally more appropriate.
For a submersible pump, the situation is different. Because the pump is already underwater, it does not use a traditional suction pipe with a foot valve. The pump or discharge plumbing may instead use a suitable check valve according to the manufacturer's instructions.
The best valve is the one designed for the job and installed in the correct part of the system.
Frequently Asked Questions
Is a foot valve the same as a check valve?
A foot valve is a type of check valve. It allows water to flow in one direction and blocks reverse flow. Unlike most standard check valves, it is designed to sit at the inlet end of a suction pipe and usually includes a strainer.
Does a foot valve increase water pressure?
No. A foot valve does not create pressure. Its main job is to prevent water from draining backward. In fact, an undersized or clogged foot valve can restrict flow to the pump.
Does every rainwater pump need a foot valve?
No. Surface pumps using suction lines may need one depending on their design. Submersible pumps generally do not use foot valves because the pump itself sits in the water. Follow the pump manufacturer's installation requirements.
Why does my pump lose prime even with a foot valve?
The foot valve may be leaking, but an air leak elsewhere in the suction line can cause the same problem. Check pipe joints, hoses, fittings, pump connections, and the valve before replacing parts.
Should a foot valve sit on the bottom of a rainwater tank?
Usually not. Sediment tends to collect on the tank bottom and can clog the valve screen. The intake should generally remain underwater while staying above heavy settled debris.
Can I put a check valve before and after a pump?
Some systems use more than one non-return valve, but adding valves without a clear reason can increase flow resistance or create operating problems. Follow the pump manufacturer's recommended plumbing layout.
Is a spring check valve better than a foot valve?
They serve different purposes. A spring check valve may work well in some pressure lines, while a foot valve is specifically useful at a submerged suction inlet. Choose according to valve location, pump requirements, pressure, flow, and water quality.
