Fix Common RV Plumbing Leaks & Clogs

1 Diagnose and Repair Freshwater Line Leaks

Water dripping under cabinets, or a freshwater pump that randomly cycles on and off with no faucet open, both point to a pressure-side line leak.

1. Turn off the city water connection.
2. Fill the freshwater tank and turn on the 12V water pump.
3. Listen carefully — if the pump runs or cycles every few minutes without a faucet running, you have a pressure-side leak.
4. Check the floor around the water heater, under the kitchen/bathroom sinks, and behind the toilet, using a dry paper towel to spot moisture.

• Loose Nuts: Most RV faucets use plastic hand-tighten swivel nuts. Reach behind the sink or shower and turn them clockwise. If they're cracked, unscrew them and replace the cone washer inside.
• Split PEX Pipe: If a pipe burst from freezing or vibration wear, use a small pipe cutter to remove the damaged section, then splice in a new piece of PEX tubing using a push-to-connect SharkBite union fitting for a tool-free, permanent fix.

2 Fix Toilet Leaks and Clogs

RV toilets drop waste directly into a holding tank and rely on a mechanical blade valve and a rubber seal to hold water and keep sewer gases out.

• Diagnostic: If the water in the bowl drains away within minutes, the rubber flush ball seal is dirty, out of alignment, or dried out.
• Repair: Shut off the water supply, then scrub mineral buildup and debris from the groove of the rubber seal with an old toothbrush and dish soap. If it still leaks, apply a coat of silicone-based plumber's grease to recondition the rubber. If the rubber is torn, use a toilet-specific seal replacement kit — turn off the water, unscrew the toilet base, and swap in the new seal.

• Diagnostic: Liquid drains slowly or bounces back up, but solids remain stuck directly beneath the toilet valve — usually because the black tank valve was left open, or too little water was used when flushing.
• Repair: Do not use harsh household chemical drain cleaners like Drano — they will destroy your RV's rubber seals and valves. Instead, pour hot water mixed with a heavy dose of enzyme-based holding tank treatment down the toilet and let it sit overnight. If that doesn't clear it, use a flexible RV holding tank swivel stick attached to a garden hose, inserted down through the toilet valve, to break up the solid mass with high-pressure water jets.

3 Fix Shower Leaks and Low Pressure

Shower pans are notorious for hidden water damage — they flex when you step on them, which cracks the fragile plastic drains underneath over time.

• Diagnostic: Run the shower while looking through the bathroom's lower access panel or the basement storage bay directly beneath the shower — look for drops pooling near the white P-trap or the drain flange.
• Repair: Access the underside of the shower pan, unscrew the loose P-trap slip nuts by hand, and replace any flattened rubber washers inside the joints. If the leak is at the drain flange itself, unscrew the metal drain basket from inside the shower cabin, scrape away the old brittle plumber's putty, apply a fresh ring of new putty, and tighten the basket back down.

• Diagnostic: If the sinks have great pressure but the shower doesn't, the issue is isolated to the showerhead or the mixing valve, not the whole system.
• Repair: Unscrew the showerhead from the flexible hose and look inside the handle connector for a small plastic water-saver disc — these frequently clog with calcium or construction debris, so clean it out. Then soak the showerhead itself in white vinegar for an hour to dissolve mineral deposits blocking the rubber nozzles.

4 Water Heater Bypass & Pressure Relief Valve Repair

The water heater is a common failure point for both leaks and a lack of hot water — always let it cool and shut off power/gas before working on it.

• Check the outside water heater access panel. If water is dripping from the brass valve near the top, your Temperature and Pressure (T&P) relief valve is failing or has lost its air pocket.

• Restoring the Air Pocket: Turn off the water heater and let it cool, then turn off the main city water supply. Open a hot water faucet inside the RV, then open the T&P valve outside by lifting the lever until water stops flowing. Snap it shut, turn the main water back on, and close the inside faucet.
• Replacing a Leaking Valve: If it continues to drip after restoring the air pocket, the valve spring is spent. Thread a new 3/4" T&P valve into the tank using Teflon tape on the threads.