Your RV water pump is humming but nothing comes out, or it runs and never shuts off. Before you replace anything, work through this troubleshooting guide — most pump problems have a fixable cause that isn't the pump itself.
Your RV water pump is one of those things that's completely invisible until it stops working — and then it's the only thing you can think about. No water pressure. Or worse: the pump runs constantly without stopping, draining your batteries overnight while you sleep.
Before you order a replacement pump, work through this. Most pump problems have a fixable cause that doesn't require a new pump.
Symptom 1: Pump Runs But No Water Comes Out
This is almost always an air-in-the-lines or empty-tank problem — not a pump failure. The pump is doing its job; it just has nothing to push.
Check your fresh water tank level
Obvious, but frequently overlooked. Many RV tank gauges read inaccurately, especially when the tank is below 25%. If you're not sure, manually check or fill it before proceeding.
Check the pump inlet strainer
Most RV pumps have a small inline strainer on the inlet side. If it's clogged with debris, the pump can't draw water. It unscrews, rinses clean in 30 seconds, and goes back in.
Check for air leaks on the inlet side
A loose fitting or cracked line between the tank and pump inlet lets air in, breaking the pump's prime. Inspect every connection on the suction side of the pump and tighten or repair anything loose.
Check the pump inlet valve
Some RV setups have a shutoff valve between the fresh tank and the pump. Make sure it's fully open.
Symptom 2: Pump Runs Constantly (Won't Shut Off)
The pump has a pressure switch that tells it to stop when the system reaches the target pressure. If it's running continuously, the system isn't building pressure — which means there's a leak somewhere, or the pressure switch has failed.
- Walk through every faucet, toilet, and water connection in the rig — look and listen for drips
- Check under sinks and at the water heater connections
- Check the toilet fill valve — a stuck or failing valve leaks water continuously into the bowl
- Check the water heater pressure relief valve — if it's weeping, it may need replacement
- If no visible leak is found, the pressure switch on the pump may be faulty and need replacement
Running pump = running clock on your batteries
A 12V RV water pump draws 5–8 amps while running. If it runs continuously overnight because of a small leak or failed pressure switch, that's 60–96 amp-hours drained from your battery bank before you wake up. If you notice the pump cycling when no water is in use, shut it off at the pump switch or breaker before going to bed and investigate in the morning.
Symptom 3: Pump Runs But Pressure Is Low
- Check for partially blocked strainer (same as above)
- Check for a kinked or partially crushed water line between pump and faucet
- Check for a partially closed shutoff valve somewhere in the system
- Low pressure can also mean the pump is at end of life and losing output — a pump that runs hot, makes grinding noises, or vibrates excessively is probably failing
Symptom 4: Pump Makes Noise But Won't Run
If you hear a click (relay energizing) but the pump motor doesn't turn, check your 12V supply to the pump. Use a multimeter to verify voltage at the pump terminals when the pump switch is on. Below 12V under load suggests a wire, connection, or fuse problem — not a pump failure. No voltage at all means trace back to the fuse, breaker, or switch.
How to Prime an RV Water Pump
After winterizing, running dry, or replacing the pump, you'll need to prime the system to get air out of the lines. Here's how:
Fill your fresh water tank
The pump needs water to pull. Make sure the tank has at least a quarter tank before starting — less than that and gauges may lie to you.
Open a faucet
Turn on a faucet closest to the pump (usually a kitchen sink). This gives air an exit route as the pump pushes water through the lines.
Switch the pump on and wait
The pump will sound like it's working hard with no load — that's normal. Let it run. Water should appear at the faucet within 15–30 seconds as air clears.
Run each fixture until flow is steady
Once water flows at the first faucet, work through the rest of the rig — other sinks, shower, toilet. Each one may have trapped air that needs to clear.
Pump won't prime after more than 60 seconds?
If the pump runs for a full minute without producing water, stop it. Either the inlet strainer is clogged, there's an air leak on the suction side, or the tank is emptier than the gauge shows. Running the pump dry for extended periods wears the impeller and shortens pump life significantly.
When to Replace vs. Repair
The decision is usually straightforward. Repair if the issue is a clogged strainer, a bad pressure switch, a blown fuse, or a loose fitting — all cheap fixes. Replace if the pump motor is mechanically dead, the pump runs hot and vibrates, or pressure has dropped significantly despite a clean strainer and no leaks.
Replacement pumps (Shurflo 2088 series or Flojet equivalents) run $60–$120 and a mobile tech can swap one on-site in under an hour. Compare that to the cost of a tow to a shop and a week wait time.
Common Question
Why does my RV water pump run but no water comes out?
The most common causes are an empty or near-empty fresh water tank, a clogged inlet strainer, an air leak on the suction side of the pump, or a closed shutoff valve between the tank and pump. Check these in order before assuming the pump has failed.
Common Question
Why does my RV water pump run constantly and won't shut off?
A pump that won't shut off means the system isn't reaching its target pressure — almost always because of a water leak somewhere. Check every faucet, the toilet fill valve, and all under-sink connections. If no leak is found, the pump's pressure switch may be faulty and need replacement.
Common Question
How do I prime my RV water pump?
Fill your fresh water tank, turn on a faucet to give air an exit, then switch the pump on. Let it run until water flows steadily from the faucet — this pushes air out of the lines. If the pump runs more than 60 seconds without producing water, check the inlet strainer and suction-side connections for an air leak.
Common Question
How much does RV water pump replacement cost?
A replacement 12V RV pump (Shurflo 2088 or Flojet equivalent) runs $60–$120 for the part. Labor for a mobile tech to swap it is typically 1–1.5 hours. Total cost in Northern California is usually $180–$280 all-in, depending on location and access difficulty.
Common Question
How long do RV water pumps last?
A quality 12V RV pump typically lasts 5–10 years with normal use. Running the pump dry frequently, poor water quality (sediment), or winterization damage shortens that considerably. If your pump is older and losing pressure or running rough, budget for a replacement soon rather than being caught without water at a campsite.
Common Question
Can I replace my RV water pump myself?
Yes — most RV water pumps are accessible and straightforward to swap. Turn off the pump, disconnect the 12V wires (note polarity), and unclamp the inlet and outlet hoses. Reverse to install. The main risk is cross-threading hose fittings or reversing polarity, so go slow. If the pump is buried behind a cabinet or the system has multiple valves, a mobile tech can do it on-site in under an hour.
If you've worked through the checklist and still can't get your water system running right, give us a call. We diagnose and repair RV plumbing on-site throughout Redding and all of Northern California. Learn more about our RV plumbing repair service.
BossBros RV Team
Redding, CA