When to Stop a Deep Well Pump: Warning Signs and Routine Checks

A deep well pump works out of sight, so the meters on the control panel are your only view of it. Run it close to its rated point, adjust flow and head with the valve, and never let it run overloaded.

Stop the pump at once if

• The current is well above the rated value at rated voltage. More than 20% over is a firm limit
• The supply voltage is far too high or too low
• The flow at normal head has dropped noticeably
• The insulation resistance has fallen below 0.5 MΩ
• The water level has fallen to the pump inlet
• There is a sudden noise or heavy vibration
• The protection switch keeps tripping

Routine checks

How often	What to do
Every day	Watch voltage, current and flow; compare with normal
Every two weeks	Measure the motor insulation resistance; it should not fall below 0.5 MΩ
Every season (about 2,500 hours)	Lift the pump, inspect it and replace worn parts

Lifting the pump out

Disconnect the power and the cable first. Then remove the outlet fittings and lift the pump pipe by pipe, clamping each lower pipe before unbolting the one above. If it sticks, work it up and down gently rather than pulling hard.

Storing a pump

If the pump will not be used for a long time, drain the water from the motor, clean and dry the outside, coat it against rust and keep it in a clean, dry place. A water-filled motor must never be left full where the temperature can fall to 0°C, or it will crack.