Repair guide
RV plumbing and water system repair
Whether you have a leak, a pressure fault, or freeze damage.
The cycling-pump diagnostic and the park-pressure problem. A pump that cycles with every tap closed is a specific, readable signal, and unregulated park water pressure is a leading cause of the damage owners then blame on the fittings.
What brings owners here
- The water pump cycles on and off with all taps closed
- The pump runs continuously and never builds pressure
- Water pressure is poor on the pump but fine on city water, or the reverse
- You have found water on the floor or in a cabinet base
- Nothing works properly since the first cold night of the season
What to observe and write down
These are observations, not repairs. Each one narrows the problem before anybody charges you for time.
- 01
Watch the pump with everything closed
Close every tap, switch the pump on, and let it build up and stop. If it clicks back on after a pause with nothing running, water is leaving the system somewhere — either a leak or a check valve letting pressure back. That is a definite finding, not a guess.
- 02
Confirm whether a pressure regulator is fitted
On city water, note whether there is a regulator at the connection and, if it is adjustable, what it is set to. Park supply pressure can substantially exceed what RV plumbing is designed for, and this is a common cause of blown fittings and burst lines.
- 03
Check the low-point drains and the water-heater bypass
A low-point drain left open or a bypass valve still set for winterisation explains a surprising number of "no water" and "no hot water" calls in spring. Both are quick to check and cost nothing.
- 04
Look in the cabinet bases and along the floor edges
Water tracks along the floor and shows up far from its source. Note where it is wet, where it is dry, and whether the wet area grows when the pump runs — that difference distinguishes a pressure-side leak from a drain leak.
- 05
After a freeze, pressurise and watch before using
Split lines and cracked fittings often hold while frozen and let go on thaw. Bring the system up to pressure while you are watching it, rather than discovering the failure when the coach is unattended.
How a technician works through it
Knowing the order matters: it tells you whether a quote skipped a step, and it tells you what a technician still has to establish before anyone can say what is wrong.
- 01
Pressurise and isolate
The system is brought up to pressure and then sections are isolated to find where pressure is lost. It converts "there is water somewhere" into a specific run of pipe.
- 02
Check the pump’s own components
Cycling can be the pump rather than the plumbing: a failed check valve, a worn diaphragm, or a pressure switch out of adjustment all produce it. These are inexpensive and are eliminated before chasing lines.
- 03
Inspect fittings at the points that move
RV plumbing lives on a vehicle that flexes and vibrates. Failures concentrate at fittings, at transitions between materials, and where lines pass through structure — not randomly along the run.
- 04
Assess for consequential damage
Water that has been running behind a wall or under a floor causes far more expensive damage than the fitting that caused it. Establishing how long it ran, and what is now wet, drives the real scope of work.
What drives the cost
We publish no dollar figures anywhere on this site, because real prices vary by market, season, and technician, and a number we invented would look authoritative and help nobody. What is stable is what moves the number.
- Whether the leak is accessible or behind a wall, under the floor, or inside a slide-out
- How long the leak ran, which determines whether flooring and framing are involved
- Freeze damage, which is typically multiple failures rather than one, and often in the least accessible places
- Whether the system uses fittings that need a specific crimp or expansion tool
- Whether the water heater, pump, and tanks need to be addressed as a system rather than a single part
Before you weigh any of that, settle who is paying. Warranty, insurance, or you works through the order that protects a claim — because authorising a repair before you have the answer is what turns a covered failure into one you funded.
Mobile or shop?
Leak location, pump replacement, fitting and line repairs, regulator and valve work, and winterisation are all routine mobile jobs. Extensive freeze damage inside walls and floors, or water damage that has reached the structure, may need shop time — but the diagnosis and the make-safe should still happen where the RV is.
Where this plays out differently
A handful of markets change the advice on this system rather than merely hosting it.
- Denver Front Range, CO
When to winterise, given that elevation and daily cycling both move the deadline earlier than the calendar suggests.
- Elkhart–Michiana, IN
Whether the winterisation that was done is actually complete, since here a partial job will certainly be found out.
Common questions
- Why does my water pump keep cycling when no tap is open?
- Because pressure is escaping. Either water is leaving the system through a leak, or a check valve — commonly in the pump itself or at the city-water inlet — is letting pressure bleed backwards. It is a genuinely useful symptom: it tells you there is a definite pressure loss rather than a vague complaint, and it narrows quickly.
- Do I really need a water pressure regulator?
- Yes, and it is among the cheapest protective devices you can fit. Park pressure varies enormously and some parks deliver far more than RV plumbing is built for. A regulator is the difference between a normal stay and coming back to a flooded coach, and the failures it prevents are exactly the ones that damage floors and cabinetry.
- The water heater bypass — how do I know if it is set wrong?
- The classic sign is plenty of cold water and no hot water at all, with the water heater apparently working. In winterisation position the bypass routes water around the tank so the tank stays empty. It is worth checking before anything is diagnosed, especially on the first trip of the season, because it looks exactly like a failed water heater.
- How much freeze damage should I expect after one hard night?
- It depends far more on where the plumbing runs than on how cold it got. Lines in a heated basement compartment can survive what lines in an unheated bay will not. The honest answer is that it has to be pressure-tested and inspected — and that finding one split is a reason to look for others, not a reason to stop.
Sources for the claims on this page
Campground water supply pressure can exceed the pressure RV plumbing systems are designed for, which is why an inline pressure regulator is standard recommended equipment.
Industry consensusIndustry-wide consensus; regulators are standard RV supply equipment
Freeze damage in RV plumbing commonly presents on thaw rather than during the freeze, because ice temporarily seals the split it created.
Professional judgmentWidely documented failure pattern; professional judgment applied to RV systems
Related systems
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.