Causes of a Leaking Pool Pump and How to Fix It

Do you have a leaking pool pump? I know it can be frustrating, and it may seem like there isn’t anything you can do about it, but don’t worry! You’re in the right place.

This post is all about easy and effective fixes for a leaking pool pump. It might sound daunting, but I’ll walk you through the process step by step to ensure success! I’ll explain the three main types of leaks, help you identify possible problem areas, and give you ideas on how to fix them. Now, let’s get your swimming pool back up and running!

Main Takeaways

  • The three most common types of pool pump leaks include suction side leaks, pressure side leaks, and shaft seal leaks.
  • If you have a suction side leak, this may be due to a cracked pump lid, cracked pipes or valves, low water level, or issues with the o-ring of the strainer basket drain plug or pump lid.
  • Pressure side leaks may occur due to issues with the impeller, the housing o-ring or gasket, the discharge pipe, or the pump housing.
  • If you do not have a suction side or pressure side leak, you may have a shaft seal leak.

Suction Side Leaks

The first thing to remember about suction side leaks is that they usually don’t show up when your pump is running. That’s because when the pump is running, it creates a vacuum inside the pipes on the suction side. When the pump is on, water travels through the pipes so fast that it usually doesn’t escape through any cracks or leaks. However, when the pump is off, the water on the suction side isn’t moving, which means it’ll find those cracks. Hence, the leaks.

One way to tell if you have suction side leaks is to look at the water inside the pump while it’s running. If you notice any bubbles, that means air could be getting into your system through a leak on the supply side.

If this looks like the problem, you’ll want to look at a couple of different potential problem areas.

Pump Lid

You’ll first want to check the lid on the pump itself. If it’s cracked, that’s likely the source of at least one of your leaks. You’ll have to either fix the crack or replace the lid.

The next thing to check is the rubber O-ring underneath the lid. The O-ring keeps the cover sealed nice and tight on the pump. If it’s old and cracked, you’ll need to replace it. If it looks okay, you might be able to lubricate the lid with a Teflon-based pool lubricant to ensure that the lead seals tightly.

Cracked Pipes & Valves

Once you’ve checked the pump lid, your next stop should be the pipes and valves. Air leaks in pipes and valves are common, but luckily, you can quickly identify them. To do this, pour water over the pipes and valves and watch for bubbles. You’ll need to replace the leaky pipe or valve if you see bubbles.

Low Water Level

You want to be sure not to overlook your pool’s water level. If it’s too low, air can enter the skimmer, causing a leaking pool pump. To fix this, fill up the pool, so the water level is between a third and halfway up the opening of your skimmer. If only all pool pump leaks were this easy to fix!

Strainer Basket Drain Plug

Finally, locate your strainer basket drain plug. What’s the condition of the O-ring? Is it cracked or not sitting right? If so, air could enter the system, leading to leaks. The easiest way to fix this is to replace the drain plug O-ring itself.

Pressure Side Leaks

If you’ve determined that the suction side is okay, it’s time to see if there are any leaks on the pressure side.

While suction side leaks are air, leaks on the pressure side are water. The extreme pressure can push water out of any place downstream of the pump strainer that’s compromised. You can tell you have a problem if you have any of the following:

  • Dripping coming from the discharge pipe
  • A pool of water underneath your pump
  • An uncharacteristically low water level in your pool

If you notice any of these, the next step is to check out these four possible problem areas.


Your impeller is on the pump’s motor shaft. Its job is to create water pressure. However, sometimes debris can damage the impeller, causing the pump to leak water. Additionally, impellers don’t last forever. They can break down after a while, creating a water leak.

If you see that the impeller is damaged or worn, your best bet is to take the motor off the pump and replace the impeller. Sometimes, the impeller might just be blocked. If that’s the case, you might just need to unclog it. Head over to my article on how to clean a pool pump impeller for step-by-step instructions.

Housing O-Ring or Gasket

Your pool pump motor lid isn’t the only place where you need to worry about a bad seal. There is another one located between the pump housing and the motor. This seal can wear down or crack over time, causing a water leak. If you replace this seal, it’s a good idea to replace the diffuser O-ring simultaneously.

Discharge Pipe

If your housing gasket looks good, your next step is to check the discharge pipe. The fitting on the discharge pipe can come off the pump, causing a water leak. Sometimes this is because of an ill-fitting seal. However, it might be due to your PVC pipe shrinking because of excessive heat. You might see this more often if you’re using a schedule 40 pipe. One way to fix this is to use schedule 80 nipples at both the suction and discharge ends. Schedule 80 is more robust and less affected by heat than schedule 40.

Pump Housing

If all the fittings and pipes coming out of the pump look good, you’ll need to check the pump itself. Unfortunately, even with new pumps, you can get hairline cracks in the pump housing. Grab a flashlight and shine it on the pump housing, looking closely for cracks.

While some people claim you can repair these types of cracks with epoxy, I haven’t had luck doing this myself because of the plastic used for the pump and the fact that it’s such an extreme-pressure environment. Most likely, you’ll have to buy a new pump housing.

Shaft Seal Leak

If you can rule out suction side and pressure side leaks, your next stop is the shaft seal. This seal sits between the pump motor and the impeller. This seal is important because it keeps water from entering the motor. When this seal fails, water can enter and cause motor failure. Any water inside the motor is bad, so you’ll want to get this fixed as soon as possible.

One way to see if this is the cause of your leaking pool pump is to listen to the motor. Does it sound abnormal? If so, it could be the motor bearings trying to work in water. The fix here is simple. Replace the old shaft seal with a new one. Just make sure you get the right one for the pump you have. I have a complete guide that you can check out on finding the right pool pump shaft seal.

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Final Thoughts

Leaking pool pumps are not fun. However, if you systematically approach the possible causes, you’ll be able to find out what exactly is causing the leak and your pump to have low water flow. Once you figure that out, you’re well on your way to enjoying your pool again! If you find out that you might need to replace the whole thing, head over to my recommendations for the best pool pumps. You can also read my guide on pool pump troubleshooting if you’re having other issues too.

Questions about a leaky pump? Drop me a line.

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