RV water pump keeps running or cycles with taps closed
What this usually means
This is a genuinely useful symptom rather than a vague complaint. If the pump builds pressure, stops, and then clicks back on with everything closed, water is leaving the system. Either there is a leak, or a check valve is letting pressure bleed backwards. Both are definite findings and both narrow quickly.
Check this first
Close every tap including the outside shower and the toilet, run the pump until it stops, then switch the pump off at the panel and listen. If pressure holds with the pump off, the loss is through the pump itself. If it drops, you have a leak in the plumbing.
Most likely causes
Ordered by how often each one turns out to be the answer, with the tell that distinguishes it.
Failed check valve inside the pump
most commonCycles regularly with no water visible anywhere in the coach.
Leak at a fitting
commonDamp in a cabinet base or along a floor edge; the wet area grows when the pump runs.
Outside shower or low-point drain left partly open
commonFree to check and regularly the answer, especially after travel.
Toilet valve not sealing
commonWater audibly trickles into the bowl, or the bowl will not hold water.
Air in the system after a tank refill
commonStarted immediately after filling; usually settles once air is purged.
Failed pressure switch
less commonThe pump never settles at all, or cycles rapidly and continuously.
What you can safely check
- 01
Close absolutely everything, including the outside shower
The outside shower and low-point drains are the two most commonly overlooked openings, and both produce exactly this symptom.
- 02
Isolate the pump and see whether pressure holds
Pump off after it has built pressure. Holding means the loss is through the pump; dropping means it is in the plumbing.
- 03
Listen at the toilet
A toilet valve that does not seal lets water past continuously and is a frequent cause. You can usually hear it in a quiet coach.
- 04
Check cabinet bases and floor edges for damp
Water tracks along the floor and appears far from its source. Note where it is wet, where it is dry, and whether the wet area grows as the pump runs.
What needs a technician
Pressure-testing and isolating sections to locate a leak behind a wall or under the floor, pump rebuild or replacement, and assessing any consequential damage where water has been running unnoticed.
Parts typically involved
So you know what a quote should be naming. We publish no prices — real costs vary by market, season and technician, and a number we invented would look authoritative and help nobody.
- Water pump
- Pump rebuild kit or check valve
- Pressure switch
- PEX fittings and crimp rings
- Toilet valve or seal kit
- Accumulator tank
When to stop troubleshooting
- You can hear water running but cannot find it — switch the pump off and close the city water connection before continuing
- Flooring feels soft near a suspected leak
Can you still travel?
Switch the pump off before driving. A pump cycling unattended on the road can empty a tank into the coach, and a leak that is a nuisance while you are watching becomes serious damage over a few hours of travel.
Common questions
- Why does the pump cycle if I have not used any water?
- Because pressure is escaping. Either water is leaving the system through a leak, or a check valve — commonly inside the pump or at the city-water inlet — is letting pressure bleed backwards. It is a definite finding rather than a vague symptom, which is exactly why it is worth acting on early.
- Should I just switch the pump off and use city water?
- It is a reasonable short-term move and it stops the cycling, but be careful about what it hides. If the cause is a leak, city water will feed it continuously and at higher pressure than the pump produces — which makes the damage worse rather than better. Fine as a stopgap while you are present; not something to leave unattended.
Related failures
For the whole system rather than this one symptom, see RV plumbing and water system repair.
Next step
Work through structured triage for this system and you will end up with a written service brief: what you observed, in what order, and what has not been established yet. It is the document that lets a technician quote properly instead of guessing on arrival.
Being straight about what this is. No technician is signed to any territory yet — not one. We do not match you, dispatch anyone, or promise a call. What you get is the brief, and a request form that copies it to us so we know the demand is real. If you need someone today, take the brief and send it to a local technician directly; it works just as well that way.