How RV Plumbing Systems Work
Learn how fresh water, gray water, and black water systems work together, and why proper maintenance prevents leaks and odors.
RV plumbing is a self-contained system that manages fresh water supply and waste disposal. Unlike a home connected to city utilities, your RV must carry its own water and hold its own waste until you reach a dump station.
The Fresh Water System
Your fresh water system consists of a holding tank, a 12V water pump, and city water connection. When camping off-grid, the water pump draws from the tank to pressurize the lines. When connected to a campground faucet, the city water inlet bypasses the pump and pressurizes the system directly.
Waste Water Systems
Waste is separated into two categories: Gray water (sinks and shower) and Black water (toilet). Each drains into its own holding tank. Proper management involves keeping black tank valves closed until full to allow solids to break down, then dumping black first, followed by gray to rinse the hose.
PEX Piping and Fittings
Modern RVs use PEX tubing (red for hot, blue for cold) with crimp fittings. This material resists freeze damage better than rigid pipe but can still burst if water freezes inside. Fittings can vibrate loose over time, causing hidden leaks behind walls or cabinets.
Important Notes
- •Always use a water pressure regulator when connecting to city water
- •Sanitize your fresh water tank annually with a bleach solution
- •Never leave the black tank valve open when hooked up to sewer - solids will pile up (the 'poop pyramid')
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