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This article describes how to prime a water pump to restore water pressure to a building. 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. Page top sketch courtesy of Carson Dunlop.

© 2009 Daniel Friedman, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use links at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

If your water pump is a two-line jet pump and if it's running but there is no water delivered to the building, the problem could be that the pump has lost its prime. This pump needs to send water down into the well (and through a special valve at the end of the water pickup-pipe in the well) in order to bring water back to the building.

See   WATER PRESSURE LOSS DIAGNOSIS GUIDE for help in determining why you have no water or no water pressure in a building. If the diagnosis determines that you need to re-prime the water pump, the instructions are provided in this article.

If your water pump is a submersible unit the pump is located down in the well itself. In this case if you have not got water pressure, the problem may be with the pump or the well itself, but it's not a loss of prime - submersible water pumps are self-priming.

If your water pump is a one-line jet pump, it is sucking water from a shallow well; you probably don't need to do so, but the instructions below show how to prime the well pump and they should work equally well for either a one-line jet pump or a two line jet pump.

If your water pump keeps losing prime, a shallow well jet pump well line could have a bad foot valve (in the well) and so be losing prime. A leak in the well line can also lead to loss of prime. If priming the well water pump using one of our methods shown below seems to fix the problem but soon the well pump loses prime again, your plumber will want to check for a bad foot valve in the well or a leak in the well piping between the well and the building. See Repeated Loss of Pump Prime.

How to Restore Lost Prime in a 2-Line Jet Pump? - How to Restore Water Pressure in a Building

If we have no water pressure, absolutely no water in the building water supply piping, and no water in the water pump, we've lost prime and the two line jet pump may be unable to bring water back from the well.

Of course other problems can cause loss of water pressure, but if the problem is lost prime in the well pump, below is the procedure for restoring water pressure in the building. We discuss various causes of loss of water pressure at WATER PRESSURE LOSS DIAGNOSIS GUIDE.

But where a two line jet pump is installed, you may have lost prime at the pump. The pump motor will run but no water is delivered. If this happens it is possible to re-prime the pump with water from another source. Check valves installed at the proper location at the pump and perhaps elsewhere can help prevent loss of prime on this system. (Other problems that can give the same symptom include internal damage to the water pump, a well that has run dry, or a piping leak between the well and the building it serves.)

If your 2-line jet pump (or other above-ground well water pump) loses prime and cannot draw water from the well, don't let it keep running as you may burn up the pump motor or damage the pump internal parts. Take these steps:

What to Do if a Water Pump Keeps on Losing its Prime

If your water pump is in the building and the pump keeps losing its prime, a shallow well jet pump well line could have a bad foot valve (in the well) and so be losing prime.

A leak in the well line can also lead to loss of prime. If priming the well water pump using one of our methods shown below seems to fix the problem but soon the well pump loses prime again, your plumber will want to check for a bad foot valve in the well or a leak in the well piping between the well and the building.

If you keep losing prime at the water pump where a two-line jet pump is installed, it's probable that a check valve at the pump or more likely at the foot valve in the bottom of the well needs to be replaced.

A second problem that can cause loss of prime is a leak in the well piping between the foot valve and the pump - anywhere along that route.

For example, a leak in the well piping inside the well can permit water in the piping and well pump to siphon backwards out of the well pump (and even the water pressure tank) down into the well when the pump as stopped.

If we prime a pump and it seems to work fine but then loses prime again after sitting un-used over night or for a longer period, we'd ask our plumber to check for a foot valve problem or a leak in the well piping.

Don't aggravate your plumber: remember to listen to your plumber. If you are too "directive" in telling the plumber what to do, s/he may do exactly what you ask even though s/he has a better idea of where the problem lies.

Carson Dunlop's sketch at left shows how a foot valve works and where it is installed. Replacing a foot valve in the well requires that the well be opened and the well piping be pulled out to permit removal of the old valve and installation of a new one.

After replacing the foot valve or well piping you should shock the well and well piping since you've probably contaminated it by laying your well piping and parts on the ground (and foot valves at the plumbing supplier are not kept in sterile containers). We discuss how to shock a well at WELL SHOCK / CHLORINATION PROCEDURE our WELL SHOCKING GUIDE

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WATER PUMPS, TANKS, TESTS, WELLS, REPAIRS
WATER PRESSURE REGULATOR ADJUST
WATER PRESSURE REPAIR GUIDE & COSTS
  Questions about lost water pressure
  Advice to a homeowner
  Adjusting Water Pump Pressure Control
  Right Repair to Pump & Tank?
  Well Pump & Tank Replacement Costs
  Reliability of Pump & Tank Repairs
  WATER PUMP PRIMING PROCEDURE
WATER PRESSURE LOSS DIAGNOSIS GUIDE
WATER PRESSURE & FLOW MEASUREMENT
  Water Pressure Intermittent
  No Water Pressure
  Well Tank relation to Water Pressure
  Shaking the Water Tank?
  Water Pressure Tank Problems
  Water Pressure Tank Diagnosis
  Water pressure Later Returns "on its own"
  Water pipe clog diagnosis
  Water pipe clog repair guide
  Making the "right" repair
  Typical Water Tank & Pump Prices
WATER PUMPS & WELL TANKS
WATER PUMP & TANK SAFETY
WATER PUMP & TANK CONTROLS & SWITCHES
  WELL PUMP PRESSURE CONTROL ADJUSTMENT
  WATER PRESSURE GAUGE ACCURACY
WATER PUMP TYPES & LIFE EXPECTANCY
  WATER PUMP, ONE LINE JET
  PUMP, TWO LINE JET
  PUMP, SUBMERSIBLE
  PUMP, WATER PRESSURE BOOSTER
  PUMP & TANK REPAIRS & COSTS
  PUMP & TANK SAFETY
WATER PUMP SHORT CYCLING
  SHORT CYCLING PUMP CAUSES
WATER PUMP & WATER TANK REPAIRS
WATER PRESSURE REPAIR GUIDE & COSTS
WATER PRESSURE LOSS DIAGNOSIS GUIDE
WATER PUMP PRESSURE CONTROL ADJUSTMENT
WATER PUMP PRESSURE CONTROL REPAIR
WATER PUMP WONT STOP RUNNING
WELL PUMP PRIMING PROCEDURE
  Prime the Pump by Garden Hose
  Prime the Pump by Priming Plug Opening
  Repeated Loss of Pump Prime
WATER SUPPLY & DRAIN PIPING
  CLOGGED DRAIN DIAGNOSIS
  CLOGGED SUPPLY PIPING / Tankless Coil & Hot Water
  PIPING IN BUILDINGS
  SEWER GAS ODORS
  WATER PRESSURE LOSS DIAGNOSIS
WATER TANK TYPES: WATER, OIL, EXPANSION, ALL
  CAPTIVE AIR BLADDER WATER TANKS
  STEEL WATER TANKS
  BIG WATER STORAGE TANKS
  OPEN WATER TANKS
WATER TANK AIR, HOW TO ADD
  WATER TANK AIR VOLUME CONTROLS
  WATER TANK AIR ADD AT AIR VALVE
  WATER TANK AIR ADD BY DRAINING
  WATER TANK AIR HOW MUCH TO ADD
  WATER TANK AIR HOW OFTEN TO ADD
  WATER TANK BLADDERS & CAPTIVE AIR
  WATER TANK BLADDER PRESSURE ADJUSTMENT
WATER TANK LIFE EXPECTANCY
WATER TANK PRESSURE CALCULATIONS
WATER TANK REPAIRS
  CONTROLS & SWITCHES on WATER TANKS
  INTERMITTENT CYCLING WATER PUMPS
  WATER PUMP SHORT CYCLING
  SHORT CYCLING DETECTION
  SHORT CYCLING CAUSES
  WATER TANK AIR LOSS SIGNS
WATER TANK REPLACEMENT
WATER TANK SIZE & VOLUME
WATER TANKS HOW THEY WORK
WATER SOFTENERS
WATER TESTS, CONTAMINANTS, TREATMENT
WELLS CISTERNS & SPRINGS

• 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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