How to Prime a Pool Pump: Step-by-Step Guide
Pool pump priming means getting water into the pump so it can create suction and circulate your pool water. Most pumps prime in 30-60 seconds when the pre-conditions are right. When they don’t, it is almost always because air is somewhere it should not be — and we find the fix is straightforward once you know where to look.
A pool pump that fails to prime is almost always missing water on the suction side. The fix: fill the pump basket with a garden hose, seat the lid O-ring, and restart. We see most pumps prime within 30-60 seconds using this method.
Before you prime: checklist (do this first)
Skipping the pre-prime checklist is the most common reason priming fails. Address each item before adding water or restarting the pump.
- Water level: Pool water must be above the middle of the skimmer opening (the skimmer throat). If the water level is too low, the skimmer pulls air instead of water and the pump cannot prime regardless of what you do. Add water first if needed.
- Baskets: Remove and clean both the skimmer basket and the pump basket. Clogged baskets restrict flow even when the pump is running and prevent successful priming.
- Valves: All suction and return valves must be fully open. A partially closed valve creates an air lock that blocks prime.
- O-ring: Inspect the pump basket lid O-ring. It should be pliable and seated in its groove with no cracks or flat spots. Apply a small amount of Magic Lube (Teflon-compatible) if the O-ring is dry. Replace it if cracked. A damaged O-ring is the single most overlooked cause of prime failure.
- Filter valve position: If you have a sand or D.E. filter with a multiport valve, make sure it is set to FILTER — not BACKWASH or RECIRCULATE.
If you are starting your pool after winter, check our guide to opening pool for the season for the full startup sequence before attempting to prime.
This guide also assumes your pump turns on and runs. If the pump won’t turn on at all, that is a different issue — see our pool pump troubleshooting guide.
This guide is for you if… / this guide is NOT for you if…
This guide is for you if:
- You are priming the pump after the pool opening for the season
- You are priming after a repair (new seal, new pump head, or wet end work)
- The pump ran dry and lost suction
This guide is NOT for you if:
- The pump keeps losing prime repeatedly within minutes of starting — that is an air leak problem, not a priming issue. See pump won’t prime or keeps losing prime for that diagnosis.
- The pump won’t turn on at all — see pool pump repair and the electrical troubleshooting guides.
Video guide
Video: “How to PRIME a Swimming Pool Pump” by Hallmark Pool Supplies
How to prime a pool pump (self-priming pump)
Most in-ground pool pumps are self-priming, meaning they are designed to pull water up from below and create their own suction — but they need a water-filled starting point to do it.
What you need: Garden hose, flathead screwdriver
- Turn off the pump at the breaker or timer switch
- Open the pump basket lid by turning counterclockwise; some lids require pressing down while turning
- Fill the basket with water using a garden hose until water reaches the top of the pump basket housing
- Replace the basket lid and hand-tighten; press down firmly to seat the O-ring. Do not overtighten — you want a good seal, not a cracked lid
- Turn on the pump
- Watch the pump basket through the clear lid — water should begin filling the basket and circulating within 30-60 seconds
- If the basket does not fill within 60 seconds: turn off the pump, refill the basket with the hose, and try again. Heavily air-locked systems sometimes require 2-3 attempts
- Check for air bubbles at return jets — bubbles should clear within 2-3 minutes once the pump is primed
For a detailed walkthrough with photos, the INYOPools priming guide{:target=“_blank”} covers several pump model variations.
What success looks like: The pump basket is completely full of water with no air visible through the lid. The pressure gauge on the filter rises to its normal operating range (typically 8-15 PSI for a clean filter). You feel strong, steady flow from the return jets in the pool.
Systems with significant elevation between the pool and the pump (the pump is installed much higher than the water level) may need extra attempts because the pump must overcome more air column. This is normal — just refill and retry.
Priming an above-ground pool pump
Above-ground pool pumps are typically not self-priming in the same way as in-ground pumps because the pump sits above or beside the pool rather than below. Gravity does not help pull water up to the pump.
For Intex and Bestway cartridge filter systems (the most common above-ground pump setups):
- Close the return valve (if present)
- Open the suction valve fully
- Remove the inlet port plug on the pump body
- Fill the pump body through the inlet port with a hose until water runs out
- Reinstall the plug
- Open the return valve
- Start the pump
Above-ground pumps may require more patience. If the suction line is long or has several fittings, it holds more air and takes longer to clear. We recommend keeping the pump running (watching for overheating) for up to 3 minutes before turning off to refill.
For above-ground pump installation and setup guidance, Hayward pump support{:target=“_blank”} provides manuals for their aboveground pump line.
When the pump primes then quickly loses water
If the pump basket fills and the pump appears to prime, but then the basket empties within a minute or two, there is an air leak on the suction side pulling air back into the system.
Most common causes:
- O-ring not sealing: The pump lid O-ring is letting air past. Try lifting and reseating the lid, or applying more Magic Lube. If the O-ring is cracked or misshapen, replace it ($5-$10).
- Check valve not holding (elevated systems): Systems where the pump sits higher than the pool often have a check valve on the suction line. When the valve leaks, the water column falls back toward the pool when the pump slows or stops. The pump must re-prime every cycle.
- Suction line air leak: A crack, loose union, or failed fitting on the suction side allows air to enter while the pump is running. Use the shaving cream test: apply foam to suction joints while the pump runs; the foam disappears where air is being pulled in.
Consider pool pump seal replacement if you find the shaft seal area is weeping water, as a failed shaft seal can also allow air to enter on some configurations.
FAQ
How long does it take to prime a pool pump?
A pool pump in good condition with no air lock primes in 30-60 seconds. If the suction line has a large air pocket (common after winter storage or after opening union fittings), expect 2-3 attempts of 60 seconds each. If the pump has not primed after 5 minutes of total run time across multiple attempts, work through the pre-prime checklist again — water level, baskets, O-ring, and valve positions account for nearly every failure.
Why do I have to prime my pool pump every time?
Needing to manually prime at every startup is not normal for an in-ground self-priming pump. It indicates an air leak somewhere on the suction side that allows the water column to fall back toward the pool when the pump shuts off. Common culprits: cracked lid O-ring, loose union on the suction line, or a leaking check valve on elevated systems. See our guide on pump won’t prime or keeps losing prime for a systematic diagnosis.
Can I run my pool pump without priming it?
No. Running a pool pump dry — even for a few minutes — damages the impeller and the shaft seal. The shaft seal relies on water to lubricate and cool it. Without water, the seal overheats and warps. A shaft seal replacement costs $30-$80 in parts; an impeller replacement runs $20-$80. Neither is difficult to repair, but both are avoidable if you prime before starting. Never run a pool pump dry — impeller and shaft seal damage occurs within minutes.
My pump basket fills but then empties when I turn it off — is this normal?
Yes, this is normal for most self-priming pump setups. When the pump stops, the water in the basket and suction line can fall back toward the pool — especially on systems without a check valve. This is only a problem if the basket also empties while the pump is running (indicating a suction-side air leak) or if the pump cannot prime at the next startup without manual assistance.
For general pool equipment startup guidance during the season, including filter backwash timing and pressure baselines, see our pool filter maintenance guide.
For more help with your pump system, see our complete pool pump troubleshooting guide and the full troubleshooting framework.
For variable speed pump startup sequences and priming considerations, Pentair pump manuals{:target=“_blank”} cover their IntelliFlo and SuperFlo VS models in detail.