Pump Sucking Air? Why That Little Leak at the Pump Points to a Bigger Problem

Quick Takeaways

• If your pump is sucking air or leaking at the unions, it’s usually a symptom of a pool leak, not just bad equipment.
• When the pool leaks, the water drops, the skimmer pulls air, and the pump and PVC fittings around it get cooked by heat.
• Those heated unions and fittings warp, and now you see a “leak at the pump” or hear constant air in the system.
• Do not pay for a replumb until you’ve ruled out or addressed the underlying pool leak, or you risk cooking the new plumbing too.
• Most equipment pads use 1½” or 2″ PVC. With good instructions, simple pump-side repairs can be DIY — if the leak situation is under control.

What “Pump Sucking Air” and Leaks at the Pump Actually Look Like

Most homeowners describe the same handful of symptoms:

• Gurgling at the skimmer when the pump is running.
• Bubbles in the pump basket that don’t clear out.
• The pump loses prime or surges, then “catches” again.
• Visible drips at the unions/fittings on the pump’s suction or return side.
• The system just “sounds wrong” compared to how it used to run.

From your point of view, all the action is at the equipment pad. It’s natural to think,
“My pump or these fittings went bad, that’s the problem.”
But in a healthy, non-leaking pool that stays at the proper water level, those pump fittings almost never just decide to start leaking on their own.

The Old-Timer Rule: “If It’s Leaking at the Pump, You’ve Got a Leak in the Pool”

Here’s the “old man wisdom” that sounds crazy until you’ve seen it a few hundred times:

If you’ve got water leaking at the input or output of the pump, you almost always have a leak in the pool first.

When I first heard that, I thought, “No, the leak is right here at the pump!” But over years of service, one pattern keeps showing up:

• Non-leaking pools that stay at the right water level and keep the pump fully primed almost never develop random leaks at the pump unions.
• When I do see a leak at the pump fittings, there is nearly always a real leak in the pool behind the scenes.

That’s why old-school leak guys don’t even argue with it. If the pump unions are leaking, they assume the pool has been leaking long enough to start cooking the plumbing.

The Chain Reaction: How a Pool Leak Cooks Your Pump Plumbing

Here’s the chain reaction in simple terms:

1. You have a real leak in the pool system.
   The net effect: water level drops more than normal evaporation.
2. The water line gets low near the skimmer.
   On and off, the skimmer starts pulling air along with water.
3. The pump runs with air in the system.
   Less water is moving through the pump and equipment, so it can’t cool itself properly.
4. Heat builds up at the pump and nearby plumbing.
   Those PVC fittings and unions (especially at the pump) are getting hot. Plastic expands and shifts.
5. The unions and fittings warp and the seals give up.
   Now you’ve got drips and air leaks at the pump. The pump is sucking air, and it looks like “the pump is the problem.”

In reality, the pump-side leak is the last step in a leak story that started in the pool. Ignore that first part and you’ll chase your tail on equipment repairs.

Why Replumbing the Pump First Is Usually a Waste of Money

Here’s the hard truth a lot of people find out the expensive way:

If you replumb a leaking pump without fixing the pool leak that caused it, there’s a good chance you’ll cook the new plumbing too.

If the pool keeps leaking, the water keeps dropping, the skimmer keeps pulling air, and the pump keeps running hot. The new fittings you just paid for end up in the same situation as the old ones.

That’s why the order of operations matters:

1. Confirm whether you have a real leak in the pool.
2. Make a plan to address the leak (full repair, short-term plan, or at least understand what you’re living with).
3. Then fix the equipment plumbing so it has a fair chance of staying tight.

Anyone who jumps straight to “let’s replumb this” or “you need a new pump” without asking about leaks and water level is skipping the most important part of the story.

Step 1: Confirm If You Really Have a Leak

Before you spend money on a pump repair, you want to know if the pool is actually leaking more than normal. The easiest way to start is with a simple bucket test.

• Run a bucket test to compare pool water loss vs. a control.
• Pay attention to how fast water drops when the pump is on vs. off.
• Make a note of how low the water gets relative to the skimmer mouth.

If your bucket test suggests a real leak, or your water line keeps creeping down, treat the equipment leak as a side effect, not the root cause.

Need help with the bucket test? Start here:
How to Run a Pool Leak Bucket Test

After the Leak Is Addressed: DIY vs Hiring a Pro for Pump-Side Leaks

Once you’ve dealt with the leak situation (or at least know what you’re dealing with), then it makes sense to talk about the actual pump-side plumbing.

The good news is that basic pump pad plumbing is not complicated on most residential pools:

• Most pads use 1½” or 2″ PVC on the pump suction and return side.
• Repairs often come down to cutting out a warped section and gluing in a fresh piece with new unions or couplers.
• With a hacksaw or PVC cutter, primer, cement, and the right fittings, many homeowners could handle straightforward fixes.

Where people get stuck is:

• Not knowing if they have 1½” or 2″ pipe.
• Having a tight, crowded equipment pad where one bad cut means a much bigger job.
• Trying to replumb while the pool is still actively leaking and cooking everything again.

That’s why we strongly suggest:

• First: Confirm / address the leak.
• Second: Decide if your pad is “simple DIY” or “call a repair tech.”

We’ll have a full DIY union repair guide and pipe size cheat sheet here:

• DIY: How to Fix Leaks at Your Pump Unions (Step-by-Step)

Who You Actually Need: Leak Detector vs Equipment Repair vs Pool Service

One more way people get burned is by calling the wrong type of company for the wrong job. In plain English:

• Pool service / cleaner (like me):
  Skimming, brushing, chemistry, filters, basic eyes-on-the-pool. Not a full-time leak repair crew.
• Leak detection pro:
  Finds and pinpoints the actual leak in the pool system. Some also do repairs; some only diagnose and patch.
• Equipment repair tech:
  The person who loves replumbing pads, replacing pumps, and fixing heaters, filters, and valves. They don’t want to make $20 cleaning leaves.

In a “pump sucking air + low water” situation, you often need both:

• A leak detection visit to confirm and address the leak.
• An equipment repair visit to clean up the cooked plumbing once the leak situation is under control.

That’s exactly where a smart directory like PoolLeakFix comes in: we help you understand the problem, then connect you to the right kind of help instead of guessing.

In time, this page will also link to:

• Leak Detection vs Equipment Repair vs Pool Service: Who to Call for What

Related Guides We’re Building Around This Problem

This “pump sucking air” topic is a whole little world by itself. As we build out PoolLeakFix, this page will plug into a full set of guides:

• Do You Really Need a New Pump or Just a Replumb?
• DIY: How to Fix Leaks at Your Pump Unions (Step-by-Step)
• How a Pool Leak Cooks Your Equipment: Skimmer Gurgles, Air in Pump, and Hot PVC
• Leak Detection vs Equipment Repair vs Pool Service: Who to Call for What
• Why You Shouldn’t Replumb the Pump Until the Leak Is Fixed

All of those are just different angles on the same truth:
if your pump is sucking air or dripping at the unions, treat it like a leak-in-the-pool story first, then fix the equipment the smart way.