The check valve on a well pump goes on the discharge side, between the pump and the pressure tank, to prevent water from draining back down into the well. The exact placement depends on your pump type. Submersible pumps use in-line check valves along the drop pipe inside the well. Jet pumps need a foot valve at the bottom of the suction line plus a check valve on the discharge side near the pressure tank.
Submersible Pump Check Valve Placement
Most submersible pumps have a check valve built right into the pump body. This is the first line of defense against backflow, but it should never be the only one. A second check valve should be installed in the drop pipe approximately 20 to 25 feet above the pump, and no more than 25 feet above the lowest water level in the well (the drawdown level). This second valve reduces the strain on the pump’s built-in valve by limiting the column of water that can fall back when the pump shuts off.
For deeper wells, additional check valves are recommended every 200 feet along the drop pipe. Without them, the full weight of the water column slams back down each time the pump cycles off, which wears out the pump and causes water hammer. Many states also require a final check valve above ground, typically positioned near the pressure tank. So a deep submersible installation might have three, four, or even more check valves spaced along the pipe from pump to surface.
Shallow Well Jet Pump Placement
Jet pumps work differently from submersible pumps. They sit above ground and pull water up through a suction line. For a shallow well jet pump, the most critical valve is a foot valve installed at the very bottom of the suction line, fully submerged in the water. A foot valve is a special type of check valve with a built-in strainer that filters out debris before it enters the pump. Without it, the suction line drains empty when the pump shuts off, and the pump loses its prime. A jet pump that loses prime can’t move water at all.
The foot valve should sit at least three-quarters of a valve diameter above the bottom of the well or water source to avoid sucking up sediment. A standard check valve cannot replace a foot valve here because it lacks the strainer and isn’t designed to open under suction (only under pressure from the upstream side).
A second check valve goes on the discharge side of the pump, before the water enters the pressure tank. This valve prevents water from cycling back through the pump when it shuts off, reduces pressure fluctuations, and helps prevent rapid on-off cycling.
Deep Well Jet Pump Configuration
Deep well jet pumps use a two-pipe system. The jet assembly (also called an ejector) sits at the bottom of the well, with one pipe pushing water down and another bringing it back up. The foot valve connects to the bottom of the jet assembly. If the ejector doesn’t have a built-in check valve, a foot valve is required. Some installations add a tail pipe below the ejector, with the foot valve at the very bottom of that tail pipe to position it deeper in the water.
Like shallow jet systems, a second check valve on the discharge line near the pressure tank is still recommended to protect the pressure tank and reduce cycling.
Why the Pressure Tank Location Matters
Regardless of pump type, a check valve near the pressure tank serves a specific purpose. It isolates the tank from the well, so the pressurized water in your tank doesn’t slowly leak back down the pipe. Without this valve, your pressure switch detects the drop and kicks the pump on again, even though nobody turned on a faucet. This is the valve that keeps your system from running when it shouldn’t be.
The check valve needs to be installed between the pump and the pressure switch. If it’s placed after the pressure switch (between the switch and the tank), the switch can’t accurately read the system pressure, which causes erratic pump behavior.
Signs of a Failed Check Valve
A failing check valve has a recognizable pattern. The most telling symptom is the pump cycling on every 35 to 45 minutes even when no water is being used in the house. The water slowly drains back into the well, pressure drops, and the pump kicks on to refill the system. In severe cases, the pump runs nearly continuously.
Other symptoms include low or fluctuating water pressure throughout the house, loud banging noises in the pipes when the pump starts (water hammer), and noticeably higher electricity bills from the pump running far more often than it should. If you shut the pump off and check your pressure gauge, a rapid pressure drop points to a leak between the pressure tank and the well. The check valve is the most common culprit.
Foot Valve vs. In-Line Check Valve
These two valves look similar and both prevent backflow, but they aren’t interchangeable. A foot valve has a built-in strainer, installs at the submerged end of a suction line, and is designed to open under the vacuum created by a pump pulling water upward. An in-line check valve has no strainer, installs anywhere along a pressurized pipe, and relies on water pressure pushing from one side to open it. Foot valves are for jet pump suction lines. In-line check valves are for submersible pump drop pipes and discharge lines near the pressure tank.
If you’re replacing a foot valve, you need to pull the entire suction pipe out of the well to access it. In-line check valves on submersible systems require pulling the drop pipe, which is a bigger job the deeper your well runs. The above-ground check valve near the pressure tank is the easiest to inspect and replace, which is one more reason it’s worth having one there.
Quick Reference by Pump Type
- Submersible pump: Built-in check valve at the pump, second valve 20 to 25 feet above the pump, additional valves every 200 feet in deep wells, and a final valve above ground near the pressure tank.
- Shallow well jet pump: Foot valve at the bottom of the suction line (submerged), plus a check valve on the discharge line before the pressure tank.
- Deep well jet pump: Foot valve at the bottom of the jet assembly or tail pipe (submerged), plus a check valve on the discharge line before the pressure tank.