Pool Pump Not Pumping Water? Causes, Tests and Noisy Pumps

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Why is my pool pump not pumping water? Usually it has lost prime: water below halfway up the skimmer, air entering at the lid or its o-ring, or a blocked basket, filter or valve. One major maker’s manual says prime should establish within about 2 minutes; if not, switch off and find the air.

The short answer

Check the water level first. Pump makers’ manuals say the pool should sit at least halfway up the skimmer opening, so the pump always has water.
Re-prime: fill the strainer pot, reseal the lid on its o-ring, restart. One manual allows about 2 minutes for prime; another allows about 3 minutes on high speed for a variable-speed pump.
Bubbles under the lid or in the return water mean a suction-side air leak: the lid, its o-ring, a union or the suction pipe, per the makers’ troubleshooting tables.
A grinding, gravel-like noise is usually cavitation, a pump starved of water, and has the same causes. A screech is usually the motor bearings, which is a motor repair.
Never run it dry. One maker says dry running damages the mechanical seal and is not covered by warranty. Electrical repairs need a licensed electrician; Queensland’s penalty for DIY electrical work is up to $40,000.

Pool pump not pumping water, or noisy: symptom, likely cause, the test that tells them apart, and the fix (from pump makers' troubleshooting tables, read 2 October 2026)
What you see or hear	Likely cause	The test	Fix	Who
Pump runs, strainer pot half empty or full of air	Water level too low; pump has lost prime	Is the water at least halfway up the skimmer opening?	Top up the pool; fill the strainer pot and restart. Prime should show within about 2 minutes	You
Steady bubbles under the lid, or bubbles coming out of the return jets	Air leak on the suction side: lid, lid o-ring, union or suction pipe	Lid hand-tight and o-ring seated? Bubbles stop when the lid is reseated?	Clean and reseat the o-ring, lubricate per the manual, replace if cracked; fix the leaking joint	You; a pool technician for pipe joints
Strong noise, weak flow, basket full of leaves	Blocked skimmer basket, pump basket or impeller entry	Switch off, open the pot, look at the basket and the impeller entry	Clear the baskets and the impeller entry	You
Pump runs and is primed, but flow is weak	Filter needs a backwash or clean; a valve is partly closed	Are all suction and return valves fully open? When was the filter last cleaned?	Open the valves; backwash or clean the filter per its manual	You
Water on the ground under the pump	Leaking pump shaft seal	Dry the pad, run the pump, watch the motor end of the pump	Replace the mechanical seal	Pool technician
Grinding or gravel-like rattle	Cavitation: the pump is starved of water (low level, blockage, undersized suction)	Does it quieten when you raise the water or slow a variable-speed pump?	Raise the water to halfway up the skimmer; clear blockages; lower the speed	You; a pool technician if it persists
High-pitched screech or whine from the motor	Worn motor bearings	Noise comes from the motor, not the pump housing	Replace the bearings or the motor	Licensed electrician or authorised service centre
Rattle or vibration through the pipes	Pipes unsupported, or the pump not mounted on a solid base	Does the noise change when you hold the pipe?	Support the pipework; mount on a concrete base	You or a pool technician
Pump will not start, hums, or trips the safety switch	No power; thermal overload tripped; jammed impeller; burnt-out motor	Burning smell? Does it restart after cooling?	Let it cool and reset; any wiring, motor or safety-switch fault goes to an electrician	Licensed electrician

Why is my pool pump running but not pumping water?

A pool pump moves water only when its strainer pot and impeller are full of water. If air gets in, or water cannot get in, the motor keeps running and nothing flows. That is what ‘lost prime’ means. One major pump maker’s manuals for three different pump models list the causes in the same order, and the first three cost nothing to check:

Water level. One maker’s manual says the pool should be kept at least halfway up the skimmer box so there is always water in the pump.
Prime. To re-prime: switch off, take off the strainer basket lid, fill the pot with water, refit the lid so it seals on the large o-ring, and switch on. One manual says that if prime is not established within about 2 minutes, shown by a strong flow, switch off and repeat. A variable-speed model’s manual says to run it on high flow for about 3 minutes to prime.
Air leaks on the suction side. The same manual says continued air under the strainer basket lid means an air leak in the suction piping. Bubbles coming back into the pool from the return jets point the same way. Start with the lid and its o-ring, because they are opened every week.
Blockages. A full skimmer basket, a full pump basket, debris at the impeller entry, a closed valve, or a filter overdue for a backwash.
A leaking shaft seal, shown by water on the ground under the pump.

The basket-lid test: if you can see air under the clear lid while the pump runs, the problem is between the pool and the pump; if the pot is full and the flow is still weak, it is after the pump, usually the filter or a valve.

Why is my pool pump so loud? Making noise and what each sound means

Most pump noise has the same causes as a pump that is not pumping, which is why the two questions are on one page. One pump maker’s troubleshooting guide lists five causes of a noisy pump:

Cavitation: a grinding or gravel-in-the-pump sound. The pump is not getting enough water, so bubbles form and collapse inside it. Fixes listed are raising the water level to halfway up the skimmer opening, and lowering the speed of a variable-speed pump until the noise stops. Low water and blockages cause both cavitation and lost prime.
Debris in the pump housing: rattling. Switch off and clear the housing and the impeller.
Pipework not supported, and a pump not mounted firmly: rattle and vibration. The guide says to mount the pump on a concrete base, not a wooden one.
Bad motor bearings: a screech or whine from the motor itself. The fix is new bearings or a new motor.

One maker’s variable-speed manual notes that running at lower speeds also cuts pump noise. If the pump is loud at full speed out of habit, how long a pool pump should run each day shows how to set a lower speed and longer run time.

The quotable version: a pool pump that sounds like it is pumping gravel is usually starved of water, not broken, and the fix is usually the water level or a basket.

When a pool pump problem becomes electrical work

If the pump will not start, hums without turning, trips the safety switch or smells of burning, stop there. In Queensland, the Electrical Safety Office says electrical work includes testing, repairing, maintaining or replacing electrical equipment. Its penalty for DIY electrical work is up to $40,000 for an individual, and up to $600,000 or five years’ jail if it exposes someone to a risk of death or serious injury. Its page on electricity around water says to have regular maintenance of pool electrical equipment done by a licensed electrician. Outside Queensland, check your own state’s electrical safety regulator for its rules.

Pump makers’ manuals draw the same line. One says that if the pump is wired into a time clock or automatic control, a qualified electrician must disconnect the wiring, and that damaged wiring must be repaired by a qualified electrician. Since 1 April 2025, Queensland has also treated extra-low-voltage water equipment designed for use inside a pool, such as pool lights and pumps installed in the pool, as prescribed electrical equipment that only licensed electricians may work on.

A thermal overload trip is the one electrical-looking symptom you can safely check. Two makers’ manuals say the pump has a built-in thermal overload that resets once the motor cools. Find out why it overheated before you run it again: a blocked impeller or a pump running dry are the usual reasons.

What does a pool pump repair cost, and when is it a new pump?

Most of the fixes in the table cost nothing but time. When they do not work, published prices are:

One Gold Coast pool-care business lists on-site pump repairs from $110, plus parts.
One national cost guide publishes a replacement pump at $500–$1,500 installed, typically $900.

A burnt-out motor means a replacement, according to one maker’s manual. That maker’s guarantee does not cover consumables such as mechanical seals, bearings or capacitors, and its manual says dry-running damage is not covered under warranty. A pump that has lost prime and run dry for hours may have damaged its seal even after you fix the air leak.

If you are replacing the pump, the energy label decides the running cost for the next decade: pool equipment explained: pump, filter and chlorinator covers star ratings and the replacement prices one Victorian marketplace publishes. If the pump is one of several things failing on an older pool, what a pool renovation costs helps you decide whether to repair or renovate, and you can compare quotes from pool businesses in Brisbane, Sydney or Melbourne.

Common questions

How do I prime my pool pump?

Switch off, remove the strainer basket lid, fill the pot with water, refit the lid so it seals on the o-ring, and switch on. One maker’s manual says to stop and repeat if prime is not established within about 2 minutes, and that continued air under the lid means a suction-side air leak.

Why is my pool pump losing prime?

Usually low water at the skimmer, a lid or o-ring letting in air, a leaking union or suction pipe, or a blocked basket. Check the water level first: the makers say at least halfway up the skimmer.

Why is my pool pump making a loud grinding noise?

Usually cavitation: the pump is starved of water. One maker’s troubleshooting guide says to raise the water level to halfway up the skimmer intake and lower the speed of a variable-speed pump. A screech from the motor is more likely the bearings.

Can I run my pool pump without water?

No. One maker’s manual says running the pump with no water may damage the mechanical seals, causing leaks and flooding, and that dry-running damage is not covered by warranty.

Can I fix my pool pump motor myself?

Not the electrical parts. In Queensland, repairing electrical equipment is electrical work, and the Electrical Safety Office puts the penalty for DIY electrical work at up to $40,000 for an individual. Clearing baskets, re-priming and replacing the lid o-ring are not electrical work.

Sources

General information only, current at 2026-10-02. Pool rules differ by state and by council, and penalty amounts are updated regularly. Confirm your own obligations with your council or a registered inspector before acting.