Step zero: bypass the water heater
Before any antifreeze goes in, find the water heater bypass — usually two or three valves on the lines behind the heater. Flip them to bypass so antifreeze routes around the tank instead of into it. Skip this and the first six gallons of pink disappear into the water heater, wasting money and leaving lines unprotected.
Then drain the heater itself: power and gas off, let it cool, pull the drain plug or anode rod, and open the pressure-relief valve so it empties fully. Never drain it hot or under pressure.
Drain everything that holds water
Open the fresh-tank drain and both low-point drains (one hot, one cold — usually small lines under the rig, often colored red and blue). Open every faucet, hot and cold, plus the outside shower, and let gravity do its work. Flush the toilet until the line is empty and dump and flush the gray and black tanks.
This step alone removes most of the water — the antifreeze or air that follows is there to chase out what gravity can't reach: pump head, valves, traps, and horizontal runs.
The antifreeze method (most foolproof)
Use only pink RV/marine antifreeze — it's propylene glycol, rated food-safe for potable systems. Never automotive antifreeze, which is toxic. Two to three gallons does most rigs.
Connect the pump's winterizing siphon hose (or an inline kit) into the jug, turn the pump on, then work through the rig: open each faucet, hot then cold, until it runs solid pink; do the kitchen, bath, shower, outside shower, and toilet (hold the pedal until pink flows). Pour a cup of pink into every P-trap and a bit into the toilet bowl to protect the seals.
Don't forget the forgotten five: the outside shower, the low-point drains themselves (crack them until pink appears), the washing machine lines if you have one, the ice maker/water dispenser line, and the black-tank sprayer connection. Those five fittings account for most springtime "I winterized but it still cracked" calls.
The air blowout method (lighter, but less margin)
The alternative: screw a blowout plug into the city-water inlet and push compressed air through the lines at no more than 30–40 PSI, opening each fixture one at a time until it spits dry. It leaves no antifreeze taste and no spring flushing — but it leaves no safety margin either. Any water pooled in a low spot or valve stays there, and 50+ PSI can damage lines and the toilet valve.
Many owners do both: blow the lines mostly dry, then antifreeze the traps, toilet, and pump. Whatever you choose, the water heater still gets drained and bypassed either way.
Beyond the plumbing
Pull the batteries (or keep them on a maintainer) — a discharged battery freezes and cracks. Top the fuel tank and stabilize it, run the generator briefly to pull stabilized fuel into its carb, and leave the fridge doors propped open with the interior clean and dry. Mouse-proof every opening — steel wool in gaps beats poison every time.
In spring, sanitize the fresh system with a quarter-cup of bleach per 15 gallons of tank capacity, let it sit, and flush until the smell is gone. Then camp.
Stuck on this one? Put Major in your pocket.
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Frequently asked questions
What temperature do RV pipes freeze at?
RV plumbing can start freezing after several hours below about 32°F, and a hard overnight freeze in the low 20s is enough to split lines and fittings in an unheated, unwinterized rig. If the rig will sit unheated where temps drop below freezing overnight, winterize it — the job costs $20 and two hours; the damage costs thousands.
Can I use automotive antifreeze to winterize my RV?
Never. Automotive antifreeze (ethylene glycol) is toxic and has no place in a potable water system. Use only pink RV/marine antifreeze made from propylene glycol, which is rated food-safe. Two to three gallons winterizes most rigs.
Is blowing out RV lines with air as good as antifreeze?
It can work well if done carefully — 30–40 PSI max through a blowout plug, each fixture opened until it spits dry. But air leaves no margin for water pooled in valves and low spots, while antifreeze physically displaces it. The most foolproof approach combines both: blow the lines mostly dry, then run antifreeze through the pump, toilet, and traps.