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A check valve on an irrigation pump should usually be installed where it keeps water from flowing backward when the pump shuts off. The best location depends on the pump type and whether the valve is protecting the suction line, the discharge line, or both.
For many surface-mounted irrigation pumps, a foot valve at the bottom of the suction pipe keeps the pump primed. A separate check valve on the discharge side, usually close to the pump, may be used when the irrigation system could push water back toward the pump.
The valve must face the correct direction. An arrow on the valve body normally shows the allowed direction of water flow.
Where a Check Valve Goes on an Irrigation Pump
There are two common locations.
On the suction line
A check valve on the suction side keeps water from draining back toward the water source after the pump stops.
This is especially important for above-ground pumps that must stay filled with water to remain primed.
For a pump pulling water from a:
- Rainwater cistern
- IBC tote
- Pond
- Shallow well
- Large storage tank
the usual arrangement is:
Water source → foot valve or suction check valve → suction pipe → pump
A foot valve is a check valve made for the end of a suction pipe. It normally includes a screen that helps keep larger debris out of the pipe.
When a foot valve is used, it should generally be installed near the submerged end of the suction line rather than directly beside the pump.
On the discharge line
A discharge-side check valve stops water in the irrigation piping from flowing backward through the pump.
The layout may look like:
Pump → check valve → pressure or control equipment → irrigation zones
When used here, the valve is commonly placed reasonably close to the pump while still leaving enough room for servicing.
A discharge check valve can be useful when:
- The irrigation pipes rise well above the pump.
- A pressure tank is connected to the system.
- Water could drain backward through the pump.
- Several pumps or water sources share connected piping.
- The pump manufacturer calls for one.
Not every irrigation pump needs a separate discharge check valve. Follow the pump manufacturer's installation requirements when available.
Foot Valve vs. Check Valve
A foot valve and a check valve perform the same basic job: they allow water to move in one direction and stop it from flowing backward.
Their locations are different.
| Valve | Typical location | Main purpose |
|---|---|---|
| Foot valve | Submerged end of suction pipe | Keeps suction pipe and pump primed |
| Suction check valve | Suction piping | Limits drain-back toward the water source |
| Discharge check valve | After the pump outlet | Prevents system water from flowing backward through the pump |
For many above-ground irrigation pumps, a foot valve is preferable to placing an ordinary check valve near the pump because it keeps more of the suction line filled.
Why Suction-Side Placement Matters
A surface pump usually cannot pump air effectively. The pump housing and suction line need enough water for the pump to establish suction.
If water drains out of the suction pipe every time the pump stops, the pump may lose its prime.
Symptoms can include:
- Pump runs but does not move water.
- Pump takes a long time to develop flow.
- Frequent manual priming is needed.
- Water repeatedly drains toward the tank or pond.
- Pump cycles poorly after shutdown.
A properly working foot valve can help prevent these problems.
However, a leaking pipe fitting can cause similar symptoms. A check valve cannot compensate for an air leak in the suction line.
Do Not Add Several Check Valves Without a Reason
More check valves are not automatically better.
Each valve creates some resistance to water flow. On a suction line, unnecessary restriction can make pump performance worse.
Extra valves also create more places for:
- Debris to collect
- Seals to leak
- Valve flappers to stick
- Pressure loss to occur
- Maintenance problems to develop
If a pump already has an internal check valve, or the system already uses a properly sized foot valve, another suction check valve may not help.
Check the pump instructions before adding additional valves.
How Far Should the Check Valve Be From the Pump?
There is no single distance that works for every irrigation pump.
For a discharge-side valve, installation close to the pump is common because it prevents most of the downstream piping from pushing water backward through the pump.
You still need enough straight pipe and working space to:
- Remove the valve
- Reach unions or fittings
- Service the pump
- Inspect for leaks
For a suction system using a foot valve, the valve belongs at the water-source end of the suction pipe rather than a fixed distance from the pump.
Keep a Foot Valve Properly Submerged
A foot valve needs to remain underwater while the pump operates.
It should also be positioned so it does not constantly pull sediment from the bottom of a rainwater tank, pond, or cistern.
In a rainwater storage system, drawing from the very bottom can pull settled dirt into the pump and irrigation system.
A floating intake or raised intake may help keep the suction point away from bottom sediment when the system is designed for one.
The intake must also remain below the lowest expected operating water level. Otherwise, the pump may draw air.
Pay Attention to Flow Direction
Installing a check valve backward can stop the irrigation system from working.
Look for an arrow molded, stamped, or printed on the valve body.
The arrow should point in the normal direction of water movement.
On the discharge side:
Pump → arrow → irrigation system
On a suction line:
Water source → arrow → pump
Always confirm the markings on the actual valve because designs differ.
Make Sure the Valve Fits the Pump System
Details about backflow-prevention needs around a water pump help evaluate delivery-pressure changes that indicate lost prime.
The check valve should match the irrigation piping rather than simply being whatever valve fits an available adapter.
Important factors include:
Pipe size
Avoid unnecessarily reducing the suction pipe to fit a smaller check valve.
A restriction on the suction side can reduce available flow and make it harder for the pump to operate correctly.
Valve type
Some check valves use a spring. Others use a flap, swing mechanism, or poppet.
Spring-loaded valves require pressure to open them. That extra resistance can matter on the suction side of a pump.
Use a valve type approved for the location and orientation you plan to use.
Material
The valve and fittings should be suitable for:
- The pipe material
- Irrigation water
- Outdoor exposure
- Expected pressure
- Water temperature
If the pump handles collected rainwater with sediment, choose components that can be inspected and cleaned.
Pressure rating
A discharge valve must be rated for the pressure the pump can produce, including pressure changes that can occur when irrigation valves open or close.
Install Serviceable Connections
Check valves eventually need inspection or replacement.
Consider placing unions or other serviceable fittings where appropriate so the pump or valve does not require cutting apart a large section of piping.
This is particularly useful around:
- Pump outlets
- Filters
- Pressure tanks
- Irrigation manifolds
- Tank connections
Do not rely on a check valve as a permanent maintenance-free part.
Watch for Debris in Rainwater Systems
Rainwater irrigation pumps often handle more debris than pumps supplied by treated municipal water.
Leaves, roof grit, algae, insects, and tank sediment can interfere with a check valve.
Upstream screening and sensible tank intake placement can reduce this problem.
A valve that does not fully close may allow water to slowly drain backward, causing the pump to lose prime.
If priming problems begin after the system previously worked correctly, inspect both the check valve and the suction piping for leaks or debris.
A Check Valve Is Not the Same as Backflow Protection
A pump check valve should not be treated as the required backflow protection between an irrigation system and a potable water supply.
Potable water means water intended to be safe for drinking.
If municipal or household drinking-water plumbing is connected to an irrigation system, local plumbing or water-provider rules may require a specific backflow-prevention device.
This is especially important when rainwater, fertilizers, chemicals, or other non-potable water sources are involved.
Keep rainwater and other non-potable systems properly separated from drinking-water plumbing unless the connection has been designed according to applicable local requirements.
Typical Rainwater Irrigation Pump Layout
A simple above-ground rainwater irrigation system might be arranged like this:
Rainwater tank → intake screen → foot valve → suction pipe → pump → discharge check valve if required → filter → irrigation controls → garden lines
Not every system needs every component.
For example, a submerged pump may already include a built-in check valve. Some pump manufacturers also specify where an external check valve may or may not be installed.
The safest approach is to start with the pump manufacturer's installation diagram and add valves only when the system design requires them.
When to Call a Pump or Irrigation Professional
A basic check-valve replacement is often a manageable DIY job when the piping is accessible and the system is simple.
Professional help is sensible when:
- The pump repeatedly loses prime despite a working foot valve.
- The suction lift is close to the pump's operating limit.
- The pump cycles rapidly.
- Pipes experience severe banging or pressure surges.
- Several pumps or water sources share one system.
- A pressure tank or automatic pump controller is involved.
- Potable and non-potable water systems are interconnected.
- Electrical pump work is required.
Repeated check-valve problems can indicate a larger system issue rather than a faulty valve alone.
Frequently Asked Questions
Should a check valve go before or after an irrigation pump?
It depends on its job. A foot valve or suction check valve goes before the pump to prevent the suction line from draining. A discharge check valve goes after the pump to stop downstream water from flowing backward through it.
Does an irrigation pump need a check valve?
Many surface irrigation pumps need a foot valve or another method of keeping the suction system primed. A separate discharge check valve is system-dependent. Follow the pump manufacturer's instructions.
How close should a discharge check valve be to the pump?
It is commonly installed reasonably close to the pump outlet, while leaving enough room for fittings and maintenance. There is no universal required distance for every pump.
Can I put a check valve directly before the pump inlet?
Sometimes, but it may not be the best place for a surface pump. A foot valve at the submerged end of the suction pipe keeps more of the suction line full. Additional suction valves can also increase flow resistance.
Why does my irrigation pump keep losing prime even with a check valve?
The valve may be leaking, stuck open, or clogged. The suction piping may also have an air leak. A loose fitting, cracked pipe, low water level, or damaged pump seal can produce similar symptoms.
Does the arrow on a check valve point toward the pump?
On the suction side, yes. The arrow normally points from the water source toward the pump. On the discharge side, it points away from the pump toward the irrigation system.
Is a check valve enough to prevent irrigation water from entering drinking-water plumbing?
No. A pump check valve is not a substitute for an approved backflow-prevention arrangement where potable and irrigation plumbing are connected. Follow current local plumbing and water-provider requirements.
