Filtration & Circulation /
Why Air Gets Into a Pool Pump System—and How to Fix It Safely
Air in a pool pump system usually points to a suction-side leak, low water level, or a lid seal problem. Start with safe checks and know when to call a pro.
Archive date: this article was written for PoolSkimmer on Oct 7, 2026 and given the earlier archive date of Jul 5, 2026 so the blog reads as an organized archive. It was not published on that date.
The meaning of air in the pump system
When air is present in the pump basket, circulation is poor or the pump has lost its prime, it is a sign that air is being drawn in on the suction side. In short, the system is taking in air from somewhere between the pool and the pump rather than water. While you may notice a little air on startup, persistent pockets are not to be expected; they will put undue stress on the pump, hamper the filter and leave the water in the pool without proper circulation.
Where to look for the cause
It is best to rule out the obvious before hunting for hidden damage. Here are the usual suspects:
- The pool water level: Should the skimmer begin to pull in air, the pump will follow suit.
- The skimmer basket: If it is clogged with debris or not seated right, it can create air pockets and interrupt flow.
- Pump or strainer basket lid: An O-ring that is dry, cracked, loose or simply dirty is one of the most frequent sources of an air leak.
- Suction side fittings: Unions, drain plugs and valve connections can let air in even if they are not visibly dripping.
- Cracks in the housing or plumbing: These can open up when the pump is in operation.
- *Restrictions*: A partial blockage will make the pump labour and can manifest as bubbles or erratic pressure.
How to check safely
Turn the pump off and allow it to come to a complete halt before touching any equipment. Put on the appropriate PPE like gloves and eye protection, particularly when dealing with wet components or clearing out debris. Be sure to observe any instructions in your manual or on chemical labels for water treatment products.
Proceed in this manner:
1. See if the water is at the proper operating level and top it off if necessary. 2. With the pump off, take a look at the skimmer basket. Clear out any debris and make sure it is in place. 3. Open the pump basket (pump must be off). Give the basket a clean and examine the lid O-ring for any signs of wear, flattening or dirt. 4. Put the lid back on and secure it per the manufacturer’s directions. 5. Once you have restarted, watch the return jets for any bubbles; their presence will confirm the issue is on the suction side. 6. Give a once over to any unions, valves or other points that have been serviced of late.
Reading the symptoms
The way the problem presents itself can be telling:
- Bubbles confined to the pump basket are often due to a small leak or a lid seal that is not holding.
- If the pump loses prime after being shut down, water is probably draining back while air comes in.
- Bubbles at the return jets mean air has made its way through the entire pump and filter run.
- A hot, surging or loud pump is likely starved for water because of a restriction.
Things to avoid
For your own safety and the good of the equipment:
- Never open the pump with it running.
- Keep your hands out of any operating suction outlet or equipment.
- Do not overtighten fittings or lids; you risk ruining the threads or seals.
- Check the water level first instead of assuming the pump is on the fritz.
- If there is any suspicion of an electrical fault or if the circulation is down, do not swim. Both the water and the electrical situation require attention before the pool is used.
Time to bring in a pro
There is no harm in calling a qualified technician if you spot a crack in the plumbing, housing or basket, or if the pump is overheating, tripping breakers or making odd noises. The same goes for moisture or burning smells, or if you cannot put your finger on the source of a suction leak despite having done the basic checks. A professional can do a pressure test on the suction plumbing and find internal damage that is not apparent from the outside.
In the end
Most of the time, air in the system is traced back to a bad seal on the pump basket lid, a low water level or some form of suction-side leak. Do the safe, elementary checks, but if you are faced with what looks like an internal failure or cracking, it is best to stop and get expert help.