Why Your Well Pump Keeps Losing Prime

Experiencing this problem right now? Call us for immediate assistance.

If your pump runs but takes a while to deliver water—or delivers air before water—it's losing prime. Prime is the water column that allows a pump to move water to the surface. When it drains away, the pump runs but moves nothing. This is particularly common with jet pumps but can affect any system.

Common Causes

Failed Foot Valve: The foot valve at the bottom of the well prevents water from draining back. When it fails, the water column drops after the pump stops.
Check Valve Failure: Check valves higher in the system serve a similar function. Failure allows water to drain back down the well.
Cracked Drop Pipe: A crack or separation in the pipe allows air to enter and water to drain out.
Low Water Level: If the water table has dropped, there may not be enough water to maintain prime.
Air Leak in Suction Line: For jet pumps, any air leak in the suction line prevents the pump from creating the vacuum needed to lift water.
Worn Pump Impeller: A worn impeller can't create enough vacuum to pull water, especially on first start.

Warning Signs to Watch For

Pump runs but no water for several seconds or minutes
Air sputters from faucets before water flows
Problem is worse after pump sits overnight
You need to manually prime the pump to get water
Pressure builds slowly compared to before

How to Fix This Problem

1. Check After Overnight Idle

Prime loss that happens overnight points to foot valve or check valve failure. The water is draining back while the pump is off.

2. Listen for Air in the System

Air sputtering before water indicates either a suction leak (jet pumps) or a cracked drop pipe (submersible pumps).

3. Inspect Visible Components

For jet pumps, check all connections on the suction side for tiny leaks. Even a pinhole can prevent proper priming.

4. Test the Foot Valve

A professional can pressure-test the system to determine if the foot valve is holding.

5. Check Water Level

Have your well's static water level measured. If it's dropped near or below the pump intake, prime loss is inevitable.

When to Call a Professional

While some minor issues can be addressed by homeowners, well system problems often require professional diagnosis. Call Southern California Well Service if:

You're not comfortable working with electrical systems
The problem persists after basic troubleshooting
You notice multiple symptoms at once
Your well is over 10 years old and hasn't been serviced

We offer same-day emergency service throughout San Diego, Riverside, and San Bernardino counties.

Frequently Asked Questions

Why does my well pump lose prime overnight?

The most common cause is a failing foot valve or check valve allowing water to drain back into the well while the pump is off.

How do I prime a well pump?

For jet pumps, fill the pump housing and suction pipe with water, then start the pump. Submersible pumps are self-priming but may need the system flushed if air has entered.

Can a submersible pump lose prime?

Technically submersible pumps don't prime the same way, but they can draw air through cracked pipes or if the water level drops below the intake.

How much does it cost to replace a foot valve?

Foot valve replacement typically costs $400-800 for a submersible system, as it requires pulling the pump. For jet pumps with accessible foot valves, costs are lower.

Need Help Now?

Southern California Well Service provides expert well pump repair and diagnostics. We've been solving well problems across Southern California since 2006.

Call (760) 463-0493 for Service