Check Valve vs Foot Valve: Key Differences
Understand installation locations, flow direction, strainers and priming functions when choosing between inline check valves and pump-suction foot valves.
A Foot Valve Is a Check Valve Designed for a Suction Inlet
Both allow flow in one direction and close against reverse flow. The difference is application: a general check valve fits within a pipeline, while a foot valve sits at the lower end of a pump suction pipe to retain the water column and screen larger debris.
| Decision factor | Inline check valve | Foot valve |
|---|---|---|
| Primary role | Prevent reverse flow within an irrigation pipeline or equipment assembly. | Help retain prime in a suction-lift system when the pump stops. |
| Typical location | Pump discharge, branch line, filter/fertigation assembly or other engineered point. | Submerged at the water-source end of the suction pipe. |
| Strainer | Not normally integral; protection is selected separately where needed. | Normally includes an inlet screen or basket. |
| Common designs | Swing, spring, ball, lift, wafer or silent check. | Swing or spring-style non-return element combined with a screened inlet. |
| Main selection risk | Excess head loss, unsuitable orientation, slow closure or damaging slam. | Undersized screen, air leakage, sediment blockage, poor submergence or loss of prime. |
An ordinary inline check valve without a suitable screened inlet is not automatically a foot valve. A foot valve on the suction side also does not replace a discharge check valve when the pump or system design requires one.
Where Each Valve Belongs
Inline check valve
Install with the body arrow in the permitted flow direction and follow the manufacturer’s orientation requirements. On pump discharge, a correctly selected valve can prevent reverse flow toward a stopped pump. Other locations may protect filters, fertigation equipment or separate zones.
Foot valve
Place the screened inlet below the lowest expected operating water level, above bottom sediment and far enough from walls or intake turbulence. All suction joints must remain airtight because a leaking joint or valve can let the water column fall and the pump lose prime.
Prime the casing and suction pipe according to the pump manual. If the pump fails to prime or loses prime during startup, stop it and correct the suction-side problem before restarting.
Choose for Flow, Pressure and Water Quality
Connection size alone does not determine valve capacity. Compare the required flow with published head-loss data and verify the complete operating envelope.
Limit pressure loss
- Design and maximum flow
- Cracking or opening pressure
- Head loss at rated flow
- Static and surge pressure
Match the system
- Body and seal material
- Water, fertilizer and chemicals
- BSP, NPT, socket or flange
- Horizontal or vertical orientation
Size the foot valve
- Screen open area
- Expected debris and sediment
- Lowest operating water level
- Inspection and cleaning access
Information to provide when ordering
Prevent Leakage, Blockage and Loss of Prime
Before startup
- Confirm the flow arrow and permitted orientation.
- Flush construction debris before fitting the valve.
- Support pipework independently of the pump and valve.
- Make every suction-side connection airtight.
- Submerge the foot valve at the required operating level.
- Prime and vent the pump according to its manual.
Routine inspection
- Check whether the suction line holds water after shutdown.
- Clean algae, leaves and sediment from the foot-valve screen.
- Inspect the disc, spring, hinge, seat and elastomer.
- Look for cracked fittings and suction-side air leaks.
- Record unusual pump noise, pressure or restart delay.
- Replace worn components with approved parts.
| Symptom | Possible cause | First checks |
|---|---|---|
| Pump repeatedly loses prime | Leaking foot valve, suction joint air leak, low water level or damaged suction pipe | Leak-test the suction line, inspect the seat and confirm submergence. |
| Low flow or cavitation symptoms | Blocked screen, undersized valve/pipe, excessive suction lift or too many fittings | Stop the pump, clean the screen and verify suction design against the pump manual. |
| Reverse flow after shutdown | Debris on the check-valve seat, worn seal, broken spring/hinge or wrong orientation | Isolate and depressurize, then inspect the valve and flow arrow. |
| Valve slams or creates surge | Unsuitable check-valve dynamics, high reverse velocity or poor valve location | Review system transients and select closure characteristics with the system designer. |
It blocks larger intake debris but may not protect small pump passages, filters, solenoid valves or drip emitters. Select the main filtration system for the actual water quality and downstream equipment.
Check Valve vs Foot Valve FAQs
Is a foot valve a type of check valve?
Yes. It is a non-return valve configured for the submerged end of a pump suction pipe and normally includes a strainer or screen.
Can I use a regular check valve instead of a foot valve?
Only if the pump and intake design specifically permit it and suitable inlet screening is provided. A general inline valve is not automatically designed for submerged suction service or intake debris.
Where should a foot valve be installed?
At the water-source end of the suction pipe, below the lowest expected operating water level and clear of bottom sediment, walls and intake turbulence. Follow the pump and valve manufacturers’ specified submergence and orientation.
Does a foot valve prime the pump automatically?
It helps retain the water column after the suction pipe and pump have been filled, but it does not eliminate the initial priming procedure. Never start a non-self-priming pump dry.
Why does a pump lose prime even with a foot valve?
Possible causes include debris on the valve seat, a worn seal, insufficient submergence, a cracked suction pipe or air leakage at a suction-side joint.
Should I install a check valve before or after the pump?
A foot valve may be used at the suction inlet in a suction-lift system. A separate check valve may be required on the discharge side. The correct arrangement depends on the pump instructions and complete hydraulic design.
Need Help Selecting a Non-Return Valve?
Send the pump model, suction lift, design flow, pipe size, water source, operating pressure, connection standard, material requirement and installation drawing. Trex Irrigation can help review the valve specification.
Technical References
Pump and valve manufacturer instructions take priority for the selected equipment.