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This article explains water supply piping check valves used on both municipal water supply piping (usually near the water meter) and on private pump and well water supply systems (usually near the well pump). Readers of this document whose building is served by a well, pump, and water tank system should also see WELL PIPING FOOT VALVES.

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WATER WELL, PUMP, & TANK CHECK VALVES

On a well and pump water supply system a check valve may be installed between the incoming water line from the well and the water pump and pressure tank, such as shown in this photograph of a one line jet pump with a check valve right at the water pump inlet. You can see the check valve as a bronze assembly at the face of the pump, connected to well piping in this photo. (A similar check valve is visible closer to the foundation wall in a different water pump installation shown in the page top photo.) You'll notice that this is a one-line jet pump system with the inlet or suction line from the well running horizontally from the face of the pump, and the outlet water line rising vertically off of the pump assembly. The pump's electric motor is at the rear of the assembly. (You can see corrosion and leaks on the water line rising from the pump assembly.) The water pump check valve helps avoid loss of prime (it keeps water from flowing backwards out of the pump and water tank and back into the well when the pump motor has stopped).

Our photos above show a tpyical brass well piping check valve. A spring-loaded internal valve permits water to flow through the valve only in one direction. The check valve helps assure that the jet pump can suck water out of a shallow well - most water pumps cannot move water if the inside of the pump assembly itself is air bound. Atop some pump assemblies you'll see a removable pipe plug which permits water to be poured into the pump to prime it. (DO NOT pour water into or onto the electric motor itself.)

In summary, a well piping check valve prevents water from siphoning back out of the water tank and water pump and down into the (presumably lower) water well when the pump stops running.

A check valve at this location is a great idea and reduces the risk that a failure of the foot valve down in the well leads to inability of the pump to draw water. The foot valve s located at the bottom of the well piping and intended to accomplish the same thing. This is "cheap insurance" or perhaps the foot valve has already failed (or was omitted) at this installation.

Check Valves on Municipal Water Supply Piping

You may see check valves installed on municipal water supply piping too, to prevent possibly unsanitary water from inside a building's piping from back-flowing into and contaminating the municipal water supply system piping during a time of loss of municipal water pressure.

Check valves installed at the right location on water system piping are a good idea and are required by national and local plumbing codes in many jurisdictions.

Check valves are also installed on drain piping such as on some sewer lines (where sewer backups are likely) and on sump pumps (discussed below).

Other Applications of Check Valves on Building Plumbing & Piping

Check valves on sump pumps: Check valves are used in other plumbing applications as well, such as on sump pump drain lines to prevent back-flow of water from the sump pump exit piping into the sump pit when the sump pump turns off.

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PLUMBING TOPICS
PIPING IN BUILDINGS
  AGE OF PIPING
  CHECK VALVES
  CLOGGED DRAIN DIAGNOSIS
  CLOGGED SUPPLY PIPING
  DRAIN & SEWER PIPING
  DRAIN NOISES
  FREEZE-PROOF PIPES
  GAS PIPING
  LEAD WATER PIPES
  LEAK TYPES, Water Supply/Drain Pipe
  PLASTIC PIPING
  REPAIR BURST LEAKY PIPES
  SEWER LINE REPLACEMENT
  TRAPS on DRAINS
  VENT PIPING
  WATER PRESSURE LOSS
  WATER SUPPLY PIPING
  Water pipe clog diagnosis
  Water pipe clog repair guide
SEPTIC SYSTEMS
WATER PRESSURE REGULATOR ADJUST
WATER PRESSURE REPAIR GUIDE & COSTS
WATER PRESSURE LOSS DIAGNOSIS GUIDE
WATER PRESSURE & FLOW MEASUREMENT
WATER PUMPS & WELL TANKS
WATER PUMP CONTROLS & SWITCHES
WATER PUMP TYPES & LIFE EXPECTANCY
WATER PUMP & TANK SAFETY
WATER SUPPLY & DRAIN PIPING
WATER TANK TYPES: WATER, OIL, EXPANSION, ALL
WATER TANK LIFE EXPECTANCY
WATER TANK REPAIRS
WATER TANK AIR, HOW TO ADD
WATER TANK BLADDERS & CAPTIVE AIR
WATER TANK BLADDER PRESSURE ADJUSTMENT
WATER TANK PRESSURE CALCULATIONS
WATER TANK SIZE & VOLUME
WATER TANKS HOW THEY WORK
WATER TESTING
WATER TREATMENT EQUIPMENT CHOICES
WELLS CISTERNS & SPRINGS
  Basement Wells
  Cisterns
  Drilled Wells - steel casings
  Driven Point Wells
  How Much Water is In the Well?
  How to Test Well Water Quantity
  How to Get More Water From a Well
  Hand Dug Wells
  Springs as Water Supply
  Well Pits
  WELL CLEARANCE DISTANCES
  WELL LIFE EXPECTANCY
  WELL PIPING CHECK VALVES
  WELL PIPING FOOT VALVES
  WELL PUMP TYPES & LIFE EXPECTANCY
  WELL PUMP PRIMING GUIDE
  WELL SHOCKING GUIDE
WINTERIZE A BUILDING

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