If you're trying to figure out exactly where to put check valve on water pump systems, you're likely dealing with a pump that keeps losing its prime or a plumbing system that makes a racket every time it shuts off. Getting the placement right isn't just a "good idea"—it's what stands between a smooth-running water system and a pump that burns itself out trying to move air instead of water.
The short answer is that it depends on the type of pump you're running, but most of the time, you're looking at placing it either at the very beginning of the suction line or right after the pump on the discharge side. Let's break down the "why" and the "where" so you don't have to take your plumbing apart twice.
Why the location changes everything
Before we grab the pipe wrench, we should talk about what this little valve actually does. A check valve is basically a one-way street for your water. It lets water flow toward your house but slams shut the second the water tries to rush back toward the source.
If you put it in the wrong spot, you might end up with a "dead head" situation where the pump can't get the pressure it needs to open the valve, or worse, you could trap air in the line. Air is the enemy of most water pumps. If the pump is spinning but only hitting air pockets, it'll overheat fast.
The intake side: Using a foot valve
For many shallow well setups or centrifugal pumps that sit above the water level, the best place to put the check valve is actually underwater. We usually call this a foot valve.
If you're pulling water from a lake, a cistern, or a shallow well, you want the check valve at the very bottom of the suction pipe. Why? Because you want the entire pipe leading up to the pump to stay full of water at all times. If the valve is way up by the pump, the water in the long vertical or horizontal pipe can drain back into the well. When the pump turns on again, it has to suck air for several seconds (or minutes) before it gets to the water.
Keeping that suction line "primed" is the whole game. If you put the check valve right at the bottom, the water stays in the pipe, the pump stays primed, and everything works the way it should the moment you flip the switch.
Placement for submersible pumps
If you've got a submersible pump—the kind that lives down at the bottom of a deep well—things are a bit different. These pumps usually have a check valve built right into the "head" or the top of the pump itself.
However, if your well is deeper than, say, 200 feet, you shouldn't just rely on that one built-in valve. The weight of a 200-foot column of water is heavy. Every time the pump stops, that water wants to hammer back down. Most pros recommend installing an additional check valve about 20 feet above the pump, and then another one every 200 feet or so if you're going really deep.
This staged placement helps distribute the pressure. If you only have one valve at the bottom of a very deep well, the "water hammer" effect when the pump shuts off can be violent enough to eventually crack your pipes or damage the pump's motor.
The discharge side: Protecting the pressure tank
Now, what if you're looking at the pipes inside your basement or utility room? Usually, you'll see a check valve located on the line between the pump and the pressure tank.
This is especially common with jet pumps. You want the valve close to the pump but before the pressure tank. This setup ensures that once the pump pushes water into the tank and builds up that 40 or 60 PSI, that pressurized water doesn't just leak back through the pump and into the well when the motor stops.
Pro tip: If you're installing a check valve near the pump discharge, try to leave a little bit of straight pipe—roughly five times the diameter of the pipe—between the pump outlet and the valve. If the valve is bolted right onto the pump, the "turbulent" water coming off the impellers can make the valve chatter or wear out prematurely. Giving it a foot or two of straight space lets the water stabilize a bit before it hits the valve.
Dealing with centrifugal pumps
For a standard centrifugal pump used for irrigation or boosting pressure, you often have a choice. If the pump is located below the water source (flooded suction), you don't necessarily need a check valve on the intake, but you definitely want one on the discharge side.
If the pump is above the water source, you're back to the foot valve discussion. But here's a mistake I see people make: they put a check valve on the intake and another one on the discharge. While it sounds like double protection, it can sometimes create an air lock. If air gets trapped between those two valves, the pump might not be able to create enough vacuum to pull the water up or enough pressure to push the air out. Usually, one well-placed valve is better than two poorly placed ones.
The spring-loaded vs. swing valve debate
While we're talking about where to put them, we should briefly mention what kind to use.
- Spring-loaded valves are usually the favorite for water pump setups. They can be installed vertically or horizontally because the spring does the work of closing the valve.
- Swing check valves rely on gravity. If you're putting one of these in, you have to be careful about the orientation. If you install a swing valve vertically with the flow going down, it'll just stay open and do absolutely nothing.
For most residential well and pump setups, a high-quality spring-loaded brass check valve is the way to go. They're quieter and less likely to cause that "thump" in the walls when the pump kicks off.
Common mistakes to watch out for
I've seen plenty of DIY jobs where the check valve was put in a spot that made maintenance a nightmare. Here are a few things to avoid:
- Burying it: If you put a check valve in the middle of a long underground pipe run, you're going to hate yourself in five years when the internal seal fails. Keep your valves accessible—either in the well casing, the pump house, or the basement.
- Wrong direction: It sounds silly, but check the arrow on the side of the valve. It happens to the best of us. If you install it backward, your pump will run, the motor will get hot, but not a single drop of water will come out.
- Too close to elbows: Just like the pump outlet, try not to put a valve right after an elbow. The water is turbulent there, which can cause the internal flapper to vibrate and wear out. Give it some breathing room.
Wrapping it up
To keep it simple: if you need to keep the pump primed, put the valve as close to the water source as possible (the foot valve). If you're trying to protect your pressure tank and household plumbing from backflow and hammer, put it on the discharge line near the pump.
If you're still staring at a pile of PVC and a pump, just remember that the goal is to keep the pump wet and the pressure where it belongs. Once you figure out where to put check valve on water pump lines in your specific house, the rest is just standard plumbing. Take your time, use plenty of thread tape or primer, and your pump will thank you with years of quiet, reliable service.