A foot valve is located at the bottom of a well and acts as a one-way check valve, allowing water to go up the pipe toward the house but not drain backward into the well. A foot valve is only used in a jet-pump situation (where the pump resides above ground and shoots some water down the well to help lift more water back up). In a submersible well pump situation, it is technically called a check valve because it sits immediately above the pump rather than below, but it is commonly referred to as a foot valve and works the same way.
A leaky foot valve or check valve allows water to drain slowly down the well piping and flow back into the well. At some point, this will reduce the pressure in the pressure switch, causing the pump to cycle back on to increase the pressure. This is called intermittent pump cycling. It can drastically increase your electric bill and occurs when no water is being drawn from the system. Unfortunately, a leaky foot valve or check valve is not the only cause of intermittent cycling.
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Determine the Cause of Intermittent Cycling
Step 1: Close the Main Valve to the House
Eliminate all other leaks. A leak anywhere in the system can cause your pump to cycle intermittently. The key is to narrow down the location as much as possible. Start by closing the main valve to the house. The main valve is the one just beyond the pressure switch. This should eliminate all leaky toilets, sinks, and household plumbing. If the pump still cycles, the leak is in the well or the pipes between the well and the main valve.
Step 2: Make a Well Pipe Termination Plug
Build a termination plug that will fit on the end of your pipe and have a pressure gauge. How you build this will vary depending on the type of pipe in your well. Basically it is just a series of pipe fittings connected together that will allow you to adapt from your pipe, seal off the end, and terminate in a pressure gauge.
Step 3: Build a Well Pipe Clamp
Build a clamp out of 2x4s. Bolt the two 2x4 boards together face-to-face with a piece of cardboard in between. Drill a hole the diameter of your pipe, down the center. Unbolt the 2x4s and remove the cardboard; there should be two crescent-shaped grooves: one on each board. Together, they will now be slightly smaller than the diameter of the pipe. This will allow you to clamp the well pipe without squashing it.
Step 4: Shut Off the Electricity
Flip the breaker at the circuit breaker panel to turn off the electricity to the well.
Step 5: Remove the Well Housing Cover
Remove the cover of the well housing. Often there is a series of eight or 10 bolts around the top. Once you have removed them, take the cover off.
Test the Well Pipe and the House Feed Pipe
Step 1: Disconnect the Well Pipe From the Feed Pipe
Attach the winch to the well pipe. There should be a gasketed flange attaching the well pipe to the sidewall. Pulling up on the flange with the winch will disconnect the pipe from the feed pipe to the house.
Step 2: Lift and Clamp the Well Pipe
Pull the pipe up out of the well a couple of feet using your winch and clamp your 2x4s onto the pipe to prevent it from falling back into the well.
Step 3: Attach Termination Plug and Pressure Gauge
Verify that the clamp is holding the pipe by lowering the winch slightly. If it is holding, remove the flange from the top of the pipe and attach your termination plug and pressure gauge.
Step 4: Pressurize the Well Pipe
Pressurize the well pipe by turning the breaker to the well back on. It should hold the pressure for longer than an hour without cycling. If the pressure holds, your pipe and check valve are not the problem. Check for leaks between the well and the house. If the pressure doesn't hold, the leak is in the well.
Step 5: Check the Well Pipe and Check Valve
Winch the well pipe the rest of the way out. If you determined the leak is in the well, you have a leak in either the well pipe or a bad check valve. Either way, you should check both by pulling the pump out and pressure testing the separate sections of the pipe and the check valve.
If your well pump cycles on and off when water is running, this is not a foot-valve issue.
Most main valves are located after the pressure switch. Closing a valve before the pressure switch (if there was one) would eliminate the possibility of a leak in the well or anywhere before the valve. Closing valves assumes that the valves are actually working and seal properly.
If you drop your well pipe into the well, you are in for a major problem as it's extremely difficult to retrieve and you may damage something. Be very careful not to let this happen. Tying an emergency rope around the pipe is a good precaution.