Water pump gives no water or low flow
Symptom
The pump gives no water or low flow, loses its prime after stopping, makes a gravel-like noise, or leaks at the seal.
Likely causes
- Pump not primed, or an air leak in the suction line.
- Foot valve stuck or leaking, or suction valve closed.
- Blocked strainer, often with sand from a well.
- Cavitation - suction too long, too small or too high.
- Worn impeller, or a seal worn by sand or dry running.
- Wrong rotation after electrical work.
Most likely and cheapest to check first.
Checks
- Check the suction valve is open and the pump is primed.
- Look and listen for air leaks on every suction joint.
- Clean the strainer and check the foot valve.
- Check the rotation arrow against the shaft when jogging.
Fix
- Prime; seal the suction joints; free or replace the foot valve.
- Clean the strainer; add a settling tank if the well carries sand.
- Shorten or enlarge the suction to stop cavitation.
- Replace the impeller or the mechanical seal, and fix the cause.
Stop the equipment if
The pump is running dry or against a closed valve. Stop it at once.
Parts you may need
Keep a spare for the main pump
A failed water pump stops the plant. Consider a complete spare pump or motor-pump unit for the main supply, plus a mechanical seal and a foot valve.
DANGERWater and electricity meet in the pump house. Keep motors and junction boxes dry and protected by residual-current devices, and lock out before opening a pump.
FIELD TIPIn frost, drain pumps, lines and meters at the end of the shift. A cracked pump body is a long stop.
⚠ Every check inside a machine starts with full lockout. Safety disclaimer