# Plumbing Repair for Laguna Niguel owners Fresh water, waste tank, fixture and pump repair on RVs, trailers and vans, from $285 to $4,500 across one to eighteen hours. Leaks inside a wall are located by pressure testing rather than exploratory holes, and a tank sensor reading full is usually fouled rather than accurate. ## Finding a leak inside a wall without cutting holes A wet spot on the floor tells you almost nothing about where the water came from. Water runs along the underside of a lauan floor, follows a wire loom, and surfaces two metres from the actual failure. Rather than cut exploratory holes, we isolate and pressure test. The system gets drained, capped at the fixtures, and charged with air to a low test pressure with a gauge on it. A system that holds for thirty minutes has no leak. One that bleeds down has one, and closing valves section by section narrows it to a single run before anything is opened. Owners who have had a leak chased by trial and error usually arrive with several patched holes and a floor that is still wet. Every one of those holes was a guess billed as labour. Pressure testing costs an hour or two and turns the rest of the job into a known quantity, which is most of the difference between the bottom and the middle of the $285 to $4,500 band. - System drained and capped at every fixture before air goes in - Low test pressure held on a gauge for thirty minutes - Valves closed section by section to narrow the leak to one run - Floor or wall opened in a single place, after the run is identified ## Fresh water lines, fittings and the city water inlet Fresh water plumbing on a modern coach is PEX, and the fitting type decides the repair. Crimp fittings use a copper or stainless ring squeezed with a dedicated tool: quick, cheap, and slightly less forgiving of a poor cut. Expansion fittings stretch the tubing over the fitting and let it shrink back, giving a full bore joint with no restriction, and they need their own tool and a warm shop to behave properly. Mixing both systems on one coach is common, because two different people worked on it, so we carry both and match what is already there instead of introducing a third standard. The city water inlet is the most abused component in the system. Park pressure in some Orange County parks runs high enough to split a fitting, and a coach without a regulator at the inlet will eventually find its weakest joint on somebody else's water supply. Fitting a regulator and a gauge is inexpensive and it is the single best thing an owner can do to a fresh water system. The other regular find is a winterisation bypass plumbed backwards, which produces a pump that runs happily and no water at the tap. ## Pumps, check valves and the cycling complaint A water pump that cycles on and off with every tap closed is telling you one of two things: there is a leak downstream, or the check valve in the pump head has failed and pressure is bleeding back into the tank. Separating them takes about ten minutes. Close the valve between pump and system, and if it still cycles the pump is at fault. If it stops, the leak is out in the plumbing. Pumps get replaced over this complaint constantly, and often the pump was fine. Pump work covers the pump itself, the inlet strainer, the accumulator tank where one is fitted, and the flexible sections either side that keep noise out of the cabinetry. A pump bolted hard to a floor without those sections telegraphs through the whole coach and then gets blamed for being loud. Gate valves and their cables are the other recurring item: the cable stretches or the handle pulls off the blade, and the valve reads closed at the handle while it is actually sitting partway open. ## Black and gray tanks, flanges and sensors Tank complaints divide into three. The first is a crack, usually at the black tank flange where the toilet bolts down, because that flange is the highest stress point in a moulded tank and a toilet that has worked loose levers it every time somebody sits down. A cracked flange means dropping the tank, which is why black and gray tank repair or replacement runs $750 to $8,500. The second is the dump valve, where a stretched cable or a seized blade leaves a valve that will not seal properly. The third is not a fault at all. A tank sensor reading full on an empty tank is fouled, not broken: tissue and solids bridge across the probes and it reads continuity for good. Replacing the sensor changes nothing, and neither does a tank treatment poured down the bowl. What works is a proper back flush and, on a bad one, dropping the tank to clean it internally. We say this before an owner authorises a sensor kit, because selling a part that cannot fix the complaint is a short conversation now and a long one at pickup. - Black tank flange inspected with the toilet removed, not through the bowl - Dump valve blades and cables checked for stretch and seizure - Tank vent verified clear, since a blocked vent slows every dump - Sensor probes back flushed before any sensor part is quoted ## Toilet, sink and shower replacement work Toilet replacement runs $300 to $1,500 across one to six hours, and the range is almost entirely about what is underneath the old one. Thetford and Dometic are the two families we fit most, and going brand to brand means the bolt pattern and flange height change, so a spacer or a new flange gets added. A gravity flush unit going in where a macerating unit was is a plumbing change rather than a swap. On a coach where the toilet has been seeping quietly for a year, the flooring under it is soft and that becomes its own line on the estimate. Shower and pan work runs higher, $750 to $5,500, because a one piece pan was usually installed before the walls went up. Replacement means cutting and rebuilding the surround, and on some coaches fabricating a pan is genuinely cheaper than sourcing a discontinued moulded one. Faucets and fixtures are the cheap end at $200 to $800, and the only real warning is that a residential fixture will fit an RV thread with an adapter but its higher flow rate empties a fresh tank faster than the owner expects. ## Plumbing differences from a van build to a fifth wheel A fifth wheel or a Class A gives you underbelly access, a real basement, and tanks on hangers that can be dropped. Work gets billed straight and there are few surprises once the coroplast is down. A camper van conversion is the opposite: tanks strapped under the floor or built into cabinetry, lines running inside furniture, and nothing standard because a builder invented it. Diagnosis on a van build frequently costs more than the repair itself does, and that is worth knowing before authorising. Food trucks and mobile medical units bring a different constraint again. Their fresh water and waste systems are inspected against health code requirements rather than RV convention, so sizing, backflow protection and sanitary fittings all matter and an improvised repair does not pass. We plumb those to the code the unit is licensed under, which occasionally means telling an owner that the quick fix they had in mind is simply not available here. ## Related - [class-c-motorhome](https://ocrv.guru/vehicles/) - [standard-fifth-wheel](https://ocrv.guru/vehicles/) - [travel-trailer](https://ocrv.guru/vehicles/) - [camper-van-conversion](https://ocrv.guru/vehicles/) - [food-truck](https://ocrv.guru/vehicles/) --- Source: https://ocrv.guru/services/mechanical-systems/plumbing-repair/ OCRV Center, 23281 La Palma Ave, Yorba Linda, CA 92887. (949) 799-3387. Serving Laguna Niguel, California. All work performed in shop. No mobile or roadside service. Licences: California Bureau of Automotive Repair ARD00288521; EPA CAL000367879. Published ranges are ranges, not quotes. Every figure traces to https://ocrv.guru/prices/.