Foot Valves on Well Piping: Explanation & Repairs InspectAPedia® -
What is a foot valve, how does a well piping foot valve work, and why do we need a foot valve on well pipes?
Foot valve failures and loss of well pump prime - diagnosis & repair
Foot valve failures and loss of water pressure or water flow - diagnosis
Jet Pumps & Water Wells, Explanation & Repair Advice
Types of wells and water supply systems and what to watch out for with each
Well pump & water tank diagnosis & repair procedures
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This article describes the foot valve used on well piping for water well Pumps & Water Wells: Explanation & Repair Advice. We provide advice about what to do when things go wrong.
Readers of this document should also see
Water Tank Types and before assuming that a water problem is due to the
well itself, see
Water pump and pressure tank repair diagnosis & cost an specific case which offers an example of diagnosis of loss of water pressure, loss of water, and analyzes the actual repair cost.
What is a Foot Valve and Why do
we need one on well piping?
An Explanation of Well Piping Foot Valves
Carson Dunlop's sketch (left) shows the main parts of a one-line jet pump well installation. Nearly all well pumping systems, one line jet pump, two line jet pump, or submersible well pump, require a foot valve installed at the bottom of the well piping.
A Well Piping Foot Valve is a one way or anti-siphon valve which is installed on the pick-up end of the water pipe near the bottom of the well.
The foot valve prevents water from flowing backwards out of the jet pump and well piping back into the well when the jet pump stops operating.
You can see Carson Dunlop's sketch of a foowet valve here.
Since you won't normally see the foot valve on well piping (it's down in the well) we have included a photograp of a well piping foot valve at the top of this page.
Our photo (left) shows the outlet end of a well piping foot valve. As you may guess, a foot valve is basically a check valve combined with an inlet strainer (visible in our page top photograph). The strainer prevents picking up large debris that could clog or jam the foot valve in its open position (or that might damage the water pump itself).
The check valve is a one-way valve that lets water flow up from the well and into the well piping. The spring loaded check valve closes when the well pump stops pumping.
Closing the check valve prevents water in the well piping from falling backwards into the well when the pump has stopped running. We need this function to keep the well piping and water pump filled with water - otherwise the well pump may lose prime, leading to loss of water in the building.
If the well piping foot valve is leaky and water runs back into the well we increase the wear on the water pump as it has to run more often, and pretty soon
the water pump will lose its prime (water inside the pump mechanism) and it may be unable to retrieve any more water from the well whatsoever.
When a shallow well appears to have "run dry" one of the first things to check is whether or not the foot valve needs to be replaced.
Foot Valve Clearance from Bottom shows that the well piping and foot valve are inserted into the well some distance from the very bottom of
the well (inches to a few feet). We need this clearance to reduce the tendency of the well pump to pick up mud and debris from the bottom of the well.
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Thanks to Alan Carson and Bob Dunlop, Carson Dunlop, Associates, Toronto, for permission to use illustrations from their publication, The Illustrated Home which illustrates construction details and building components. Carson Dunlop provides home inspection education, publications, report writing materials, and home inspection services. Alan Carson is a past president of ASHI, the American Society of Home Inspectors.
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