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Pool Pump Leaking? Here’s How To Fix It (Complete Guide)

A leaky pool pump can be noisy, dangerous, and expensive.

Leaks increase your water bill and can damage the motor, so they need to be repaired as quickly as possible. The good news is that most pump leaks can be fixed without breaking the bank or getting a new pump.

If your pool pump is leaking from any of these locations, you’ll find the fix in this article:

  1. Pool pump leaking from bottom
  2. Pool pump leaking at housing
  3. Pool pump leaking from lid
  4. Pool pump leaking at connection
  5. Pool pump leaking from top
  6. Pool pump gasket leaking
  7. Pool pump leaking between motor and pump
  8. Pool pump leaking from backwash
  9. Pool pump leaking when off

In this article, I’ll show you why your pool pump leaks from various locations, what you can do about it, and how you can stop the leak right away. I’ll also provide a few ways you can prevent the pump from leaking down the road.

1. Pool Pump Leaking From Bottom

Pool pumps leaking from the bottom usually show there’s a leak between the housing and motor, or the bottom is cracked.

The bottom of a pump can crack after it’s moved or set down too harshly. It can also crack if it vibrates from high pressure against a concrete pad, rocks, or whatever sits below it.

However, most pumps don’t crack on the bottom. It might seem like the leak is coming from below, but it’s likely coming from another source.

The water flows down the side of the pump in small drips, which makes it seem like it comes from under the pump. However, it could be puddled from another area on the pump.

How To Fix

Unfortunately, you can’t fix cracks in the bottom of a pool pump.

DIY epoxy repairs aren’t enough; the water pressure would tear through the adhesive quickly. Instead, you’ll have to replace the broken pump housing.

Here’s how to replace the housing:

  1. Turn off the power to the pump.
  2. Remove the screws around the pump housing to separate it from the motor.
  3. Place the old pump housing gasket on the new pump housing.
  4. Connect the new pump housing to the motor with the previously removed screws.
  5. Prime the pump by filling the basket with a hose until the basket overflows, seal the lid, and open the air relief valve until water comes out.

Read the instructions below if you think your pump’s housing gasket is leaking.

2. Pool Pump Leaking At Housing

Pump housing leaks come from a broken, warped, dry, or misaligned pump housing gasket.

The gasket sits between the pump and the motor and is often overlooked since it sits flush with the housing. It prevents water from getting into the motor, which keeps the bearings from getting rusted and the pump from overheating.

A faulty pump housing O-ring is one of the worst issues for pumps because of how quickly it can ruin the motor.

Another potential problem is that the pump housing gasket might’ve gotten too dry. Failure to run the pump for several months or not lubricating the gasket can make it dry out.

Over time, the dry gasket cracks and warps from the sunlight and heat. The broken gasket is no match for the pump’s high PSI, which increases the chances of the motor flooding.

How To Fix

Once you know your pump’s housing seal is broken or damaged, you can replace or treat it. Make sure you get the correct part number from the manufacturer since there’s no such thing as a universal pool pump O-ring.

You can also lubricate the gasket if it’s dry, but cracked, warped, and broken gaskets have to be replaced.

Follow these instructions to replace the pump housing O-ring:

  1. Turn off the pump.
  2. Remove the retaining screws between the pump housing and the motor.
  3. Pull the old gasket off of the pump housing.
  4. Use pool and spa O-ring lubricant on the gasket.
  5. Place the new gasket in its place.
  6. Seal the retaining screws between the pump housing and the motor and prime the pump with the previously mentioned method.

3. Pool Pump Leaking From Lid

Pump lids are built to withstand tons of pressure. (These see-through lids are much more durable than they look.)

However, they tend to leak after several years of operation.

The three reasons a pool pump’s lid can leak include:

  1. The lid O-ring is damaged, warped, or missing.
  2. Your pump’s plastic lid is cracked.
  3. The pump’s lid ring is broken or loose.

A damaged pump lid is like a ticking time bomb that can quickly worsen the leak. Once the crack gets big enough, the lid will blow off the pump and send water in all directions.

It can be quite dangerous, not to mention the fact that you’ll have to replace the lid, O-ring, and likely a few other parts.

How To Fix

Pool pump lids leak immediately if they have an O-ring. The good news is that they’re very easy to treat or replace. Here’s what you should do:

  1. Turn off the pump to prevent the pressure from pushing the lid off.
  2. Remove the pump’s lid.
  3. Pull the old O-ring from underneath the pump’s lid and place the new one under the lid.
  4. Lubricate the O-ring if it’s not pre-lubricated when it arrives.
  5. Seal the lid on the pump and turn on the pump to ensure it doesn’t leak.

Hayward Multilube is a great O-ring and gasket lubricant for all of your pool and spa seals. Apply a pea-sized bead to the pump lid’s O-ring, spread it evenly all over it, then place the O-ring under the lid.

If the pump’s lid is broken, get a like-for-like lid replacement from the manufacturer with the correct part number or SKU.

4. Pool Pump Leaking At Connection

Every pool pump has two unions. One union is considered the inlet (in front of the pump), and the other is called the outlet (on top of the pump).

The inlet union is on the suction side, whereas the outlet union is on the pressure side of the pump heading toward the filter and other equipment.

Both of these unions can leak from the following causes:

  • The unions are cracked, which could happen if the plumbing is installed incorrectly or the unions are bent too often.
  • If a union O-ring is missing, the union will always leak because there’s nothing to seal the water flow.
  • Loose unions can’t prevent water from leaking out of the pump.
  • Sunlight can warp the unions, preventing them from making secure contact with the pump.

How To Fix

Much like repairing or replacing the pump’s lid, unions are often quite easy to deal with.

If you need to replace or lubricate the O-ring, simply twist off the union and fix the seal. All pump unions can twist off, revealing the O-ring. Get a like-for-like seal, and you’ll be good to go.

It’s best to lubricate your pool equipment’s O-rings and gaskets at least once a year.

Follow these instructions to replace a broken union:

  1. Turn off the pump.
  2. Saw off the union with a PVC saw.
  3. Use PVC glue to connect the exposed PVC to the new union.
  4. Push the new union toward the threaded inlet on the pump, then twist the union to tighten it.

5. Pool Pump Leaking From Top

If your pump leaks from the top, it could be the pump housing seal, lid, lid seal, or a crack somewhere in the pump.

Most pumps are built to handle direct sunlight and lots of PSI for a long time.

However, they can crack if something gets dropped on them. Almost every seal on the pump can leak from the top of the pump.

Another thing to remember is that pool pumps sit below most other pieces of equipment and plumbing. The filter’s air bleed valve, broken plumbing, and loose unions can drip on the pump, giving the impression that the pump is leaking from the top.

How To Fix

If your pump’s lid leaks, you’ll need to replace either the lid or the O-ring, depending on the source of the leak.

The best way to find the source is to remove the lid and look for cracks, and check the O-ring for cracks, dryness, and tears.

These signs show the O-ring needs to be replaced for covered in pool and spa lubricant.

Wipe the pump dry before assuming there’s a crack. The air relief valve can cover the pump and make it drip, which could make you assume there’s a leak. Don’t forget to look for leaks above the pump.

Replace all of the O-rings if they’re damaged or cracked, then lubricate the ones that don’t need to be switched.

Pro-tip: Tighten the unions every few weeks to ensure they’re not too loose. Loose unions gradually leak. It’s not worth replacing all of the plumbing if the unions are the only issues.

6. Pool Pump Gasket Leaking

Pool pumps come with plenty of gaskets, all of which can break, crack, and leak. There are several O-rings and gaskets, including the following:

  • Union gaskets leak between the connections from in front and on top of the pump.
  • The pump seal leaks from behind the impeller, which sits between the pump and motor.
  • A damaged pump housing gasket leaks between the pump and the motor, but it surrounds the impeller.
  • The pump’s lid O-ring can leak from under the lid.
  • Diverter valve or check valve leaks in the O-rings and gaskets can invite air bubbles into the system, which prevent your pump from priming.

How To Fix

Annual gasket check-ups will prevent your pool pump from leaking unexpectedly. Since unions and O-rings are the most common sources of leaks in a pump, it’s important to inspect them.

Lubricant should be added to each of the seals on the pump, heater, salt system, filter, and any other equipment you have.

Replace any torn, cracked, or otherwise damaged O-rings. They can’t be fixed or reused, not to mention the fact that they’re quite inexpensive to replace. Always look for the gasket that’s recommended by the pump’s manufacturer.

If the gasket isn’t torn or damaged, it should be lubricated. The previously mentioned O-ring lubricant from Hayward is more than enough to handle all of the gaskets on your pool equipment pad.

7. Pool Pump Leaking Between Motor and Pump

Pumps have a pump housing gasket between the pump and the motor that can leak (as discussed above).

However, they also have a vital pump seal. This pump seal, also known as a shaft seal, can cause the pump to leak uncontrollably.

This seal is a small, ½-inch thick ring that fits in the back of the impeller. The impeller is a small propeller-style part that spins in the opposite direction.

Pump seals leak if they’re touched by hands.

That’s right! The oil on your hands is enough to ruin the seal. They’re incredibly sensitive, unlike every other O-ring and gasket on the pump. They can also get misaligned from the pump’s vibrations.

I suggest replacing the pump seal every time you switch the impeller (which shouldn’t be more than once every handful of years).

How To Fix

Pool pump seals can last a long time, so they don’t need to be replaced on a schedule. Furthermore, you don’t have to inspect the pump seal too often.

You only need to replace the pump seal if it’s leaking. There’s no need to put the gasket lubricant on the pump seal since it’s a different material.

Here’s the method to replace the pump seal:

  1. Turn off the pump and remove the four to six screws connecting the pump housing to the motor.
  2. Remove the impeller from the motor using a strap wrench and a Phillips screwdriver.
  3. Pull off the pump seal from the back of the impeller (it looks like a black and white donut).
  4. Carefully place the new pump seal in its spot without touching the white surface (the white surface is immediately ruined from our natural hand oils).
  5. Secure the impeller to the motor with the Phillips screwdriver, then attach the motor to the pump housing with the previously mentioned four to six screws.

8. Pool Pump Leaking From Backwash

Pool pumps send water to the filter, which can backwash to clean the sand or DE.

Some filters have a multiport valve, while others use diverter valves to determine the direction of the water flow.

If your filter’s backwash valves are leaking, it’s likely from one of these four sources:

  1. The backwash hose is torn. Backwash hoses are often made of thin, flexible plastic or rubber. While it’s quite useful for directing the backwash flow, the material is prone to ripping.
  2. The valve’s O-ring or gasket is damaged. I’ve already covered how essential O-rings are, which is why it’s important to maintain the backwash valve’s gaskets.
  3. The backwash hose’s retaining bracket is loose or broken. These brackets tighten with metal screws. If the brackets or screws break, the retainer lets water out of the hose.
  4. The valve is cracked. Multiport and diverter valves are quite durable, but they can break. Direct pressure or improper use can permanently damage the valve. These small cracks let water through, causing the pump and filter to leak every time you turn it to the backwash setting.

How To Fix

Try these suggestions to fix a leaky backwash on a filter pump:

  • Get a new backwash hose with the correct dimensions as labeled by the company.
  • Replace all leaky O-rings and coat them in the aforementioned O-ring lubricant.
  • Place a new retaining bracket around the backwash hose every year to prevent rust from ruining it.
  • Annually inspect the valves for cracks and twist on a new one if there are signs of damage.

9. Pool Pump Leaking When Off? Here’s What To Do

Does your pool pump leak when it’s off? Most pump leaks occur from the high pressure when the motor is running.

However, severe leaks and poor plumbing can cause water to drip out of the pump. These leaks usually occur near the bottom of the pump since gravity pulls the water downward.

If your pump leaks when it’s not operating, these are the most common explanations:

  • The pump has a crack in the housing. Pump housing cracks are rare because they require a strong blow to the pump. If you didn’t drop the pump or there wasn’t an earthquake recently, it’s probably not the cause.
  • One of the unions is loose. If there’s a loose union, it can’t hold the water, even if the water isn’t moving.
  • The pump housing has loose screws connecting to the motor. Stripped screws can let water through the pump housing. If you recently had work done on the motor, housing, O-rings, or impeller, these screws might’ve not been tightened enough.

How To Fix

If the pump housing is cracked, it has to be replaced. You can’t repair a cracked pump housing because it handles too much PSI.

However, loose unions can quickly be tightened clockwise to prevent leaks. Don’t forget to check if the O-ring is misaligned since loose unions typically let the gaskets fall out of place.

You could also tighten the pump housing screws every time someone works on the motor, impeller, pump housing gasket, or pump seal.

Never tighten the screws with a power tool since they can crack the pump housing. Instead, use a Phillips screwdriver to tighten each screw until it’s snug and doesn’t leak.

Additional Pool Pump Troubleshooting Resources

If you have any other issues with your pool pump, check out our other pool pump troubleshooting articles: