RV OWNER’S FIELD GUIDE
Plumbing & Water System Troubleshooting
Low pressure, a pump that won’t stop running, no hot water, or a sulfur smell — most RV plumbing complaints trace back to one of a handful of causes. Here’s how to narrow it down.
Low Water Pressure
Pressure loss almost always has one of these causes, in rough order of likelihood:
— A clogged inline water filter — check and replace first, it’s the cheapest fix
— A failing water pump losing prime or worn internally
— A city water pressure regulator that’s failed or set too low
— A partially closed valve somewhere in the supply line
— A kinked or crushed supply line, common after storage or a rushed hookup
Water Pump Runs Constantly or Cycles Rapidly
A pump that won’t shut off almost always means there’s a leak somewhere downstream keeping the pressure switch from satisfying — the pump itself is rarely the actual problem.
— Check every visible fitting, faucet, and toilet valve for a slow drip while the pump is running
— A leak inside a wall or under the floor won’t be visible — listen for the pump cycling with everything off
— Rapid short-cycling (on/off every few seconds with no leak found) usually means a failing pressure switch or waterlogged accumulator tank
— A pump that runs continuously and never builds pressure at all suggests a lost prime or a cracked impeller
No Hot Water
Check the bypass valve position before anything else — it’s the single most common cause and the easiest to miss.
— Water heater bypass valve left in the winterized (bypass) position — the tank never fills
— No hot water on gas only: check LP supply, igniter, and thermocouple
— No hot water on electric only: check the heating element and thermostat
— Sulfur smell in hot water specifically: the anode rod (on tank-style heaters) needs replacing
Sewer Odor or Slow Drains
Sewer smell inside the RV is a venting or trap problem, not a tank problem — chasing the black tank won’t fix it.
— Check P-trap water levels first — a dry trap after sitting unused lets sewer gas straight through
— Inspect the roof vent for blockage — insect nests are a common culprit
— A cracked or separated vent line inside a wall will smell but isn’t visible without opening the wall
— Slow drains with gurgling point to the same venting problem, not a clog
Winterizing Basics
If you’re in a climate where temps drop below freezing, winterizing is not optional. Either blow out the lines with compressed air or use RV antifreeze — never automotive antifreeze. Verify the water heater bypass is set correctly before adding antifreeze, or you’ll fill the tank with it for nothing. Miss one low-point drain and you’ll be replacing split lines in the spring.
When to Stop and Call a Professional
Leaks inside walls or under flooring, a pump that won’t hold prime after basic checks, or any sign of water damage on ceilings or floors are worth a proper diagnosis before they get worse. A full system pressure test finds the actual source instead of chasing symptoms.