Check Valves (FPT x FPT) act as a critical one-way barrier in your irrigation mainline, solving two major challenges in landscape watering. First, they protect your clean home water supply from contamination by snapping shut the moment pressure drops, preventing fertilizers, soil, or bacteria from back-siphoning into your drinking water.
Second, they are highly effective for managing irrigation on hillsides and downward slopes. When the system shuts off, gravity normally causes water to drain out of the lowest emitters, flooding the bottom of the hill while starving the plants at the top. By pairing this check valve with the appropriate PVC fittings and installing it on the slope, the internal 1/2 pound spring holds the water back in the line, ensuring perfectly balanced watering across all elevations. They are also widely used to eliminate damaging back pressure in water pump systems.
Detailed specifications for system planning.
| Specification | Details |
|---|---|
| Connection Type | FPT x FPT (Female Pipe Thread) |
| Available Sizes | 3/4", 1", 1 1/2", 2" |
| Internal Mechanism | 1/2 pound internal spring |
| Primary Applications | Backflow prevention, slope drainage control, pump systems |
Follow these steps to securely integrate a check valve into your irrigation system.
Step 1: Choose the Location
For backflow prevention, install near the water source. For slope control, install it on the downward slope of the hill. For pump systems, install just after the pump outlet.
Step 2: Note the Flow Direction
Look closely at the body of the check valve. You will see an arrow indicating the direction of water flow. Ensure this arrow points toward your emitters and away from the water source.
Step 3: Apply Thread Sealant
Wrap Teflon tape 2-3 times around the Male Pipe Threads (MPT) of the PVC or poly fittings you are connecting to the valve to ensure a watertight seal.
Step 4: Thread and Tighten
Thread your MPT fittings into the FPT connections on both sides of the check valve. Hand-tighten until snug, then give an extra quarter-turn with a wrench if necessary, being careful not to overtighten and crack the plastic.
How do Check Valves protect my sloped garden during heavy summer watering?
During peak summer watering, Check Valves prevent water from draining out of the lowest emitters when the system shuts off. This stops the bottom of the hill from overwatering and flooding while higher plants dry out.
By holding the water back in the line, the system also pressurizes much faster the next time it turns on, saving water and providing instant hydration to all elevations simultaneously.
Do I need a Check Valve for my flat yard?
While not needed for slope drainage on a flat yard, a Check Valve is still highly recommended to prevent contaminated water from back-siphoning into your clean home drinking supply.
Keep in mind that many local municipalities actually require some form of backflow prevention device on all outdoor irrigation lines, regardless of whether the yard is flat or sloped.
What thread type do these Check Valves use?
These Check Valves feature Female Pipe Threads (FPT) on both the inlet and outlet. You will need standard Male Pipe Thread (MPT) PVC or poly fittings to connect them to your irrigation mainline.
Because these are pipe threads and not hose threads, they will not screw directly onto a standard outdoor garden faucet or hose bibb without a specialized adapter.
Why is there a 1/2 pound internal spring in the Check Valve?
The 1/2 pound internal spring in the Check Valve ensures the valve closes firmly and immediately when water pressure drops, successfully preventing back-siphoning and eliminating back pressure in pump systems.
This minimal spring tension is strong enough to snap the valve shut quickly, but light enough that normal forward water pressure easily pushes it open during regular watering.
Please note the requirements for this unit:
Ensure your mainline is built correctly with these recommended components:
Jun 2nd 2026
Jun 1st 2026
May 29th 2026
May 28th 2026
