Frozen water lines are one of the most expensive RV repairs there is — cracked pipes, burst fittings, and damaged pump heads can run $500–$2,000+ to fix. Winterizing takes 1–2 hours and costs about $20 in antifreeze. It's the most cost-effective RV maintenance you'll do all year.
When to Winterize
Winterize your RV when overnight temperatures in your storage area will consistently drop to 32°F (0°C) or below. Water expands 9% when it freezes — that expansion is what cracks pipes, fittings, and pump chambers. Even a single hard freeze can cause damage if the system isn't protected.
For most of the continental US, the safe window is late October through early November. In the Mountain West, Midwest, and northern states, September is not too early.
Before You Start
- Dump and clean the black water tank (full guide here)
- Dump the gray tank
- Turn off and drain the water heater — allow it to cool fully before draining
- Remove and bypass any inline water filters (antifreeze can damage filter media)
- Gather your supplies: RV antifreeze (2–3 gallons), pump converter kit or hand pump, water heater bypass wrench if needed
Method 1: Antifreeze (Recommended for Most RVs)
Step 1: Drain the Fresh Water Tank
Open the fresh water tank drain valve — usually a petcock under the RV — and let it drain completely. Some RVs also have a low-point drain on the water lines; open these as well. Tilt the RV if possible to get as much water out as possible before adding antifreeze.
Step 2: Bypass the Water Heater
Your water heater holds 6–10 gallons. Without a bypass, you'd use 6–10 extra gallons of antifreeze just to fill it. A water heater bypass kit routes antifreeze around the heater — you protect the pipes without wasting antifreeze on the heater tank (the heater has a sacrificial anode that protects it when empty). Most RVs built after 2010 have bypass valves already installed. Confirm yours are in bypass position before proceeding.
Step 3: Connect the Antifreeze Supply
Use a pump converter kit — a piece of tubing that replaces the pump's inlet filter and drops into the antifreeze jug. Turn on the water pump (12V) and it will pull antifreeze directly from the jug and pressurize the lines. Alternatively, a hand pump (non-electric) does the same job without needing battery power.
Step 4: Run Antifreeze Through Every Fixture
Starting with the faucet closest to the water pump, open the cold side until pink antifreeze flows steadily, then the hot side. Move to the next faucet and repeat. Work your way through every fixture in this order:
- Kitchen sink (hot and cold)
- Bathroom sink (hot and cold)
- Shower (hot and cold)
- Toilet — flush until antifreeze appears in the bowl
- Outdoor shower (if equipped)
- Icemaker water line (if equipped) — disconnect and blow out or run antifreeze through
- Washing machine connection (if equipped)
Step 5: Protect P-Traps and Tank Valves
Pour 1–2 cups of RV antifreeze directly down each sink drain, the shower drain, and the toilet bowl. This protects the P-trap (the U-shaped pipe under each drain) and the tank inlet valves from freezing. Don't skip this step — P-trap cracks are a common winterizing failure point.
Step 6: Turn Off and Disconnect
Turn off the water pump. Close all faucets. Disconnect the shore water connection if you have one and blow it out. Remove any external water filters. Leave a note on your dash or by the entry door reminding you the system is winterized and needs de-winterizing before use.
Method 2: Compressed Air Blowout
The compressed air method blows all water out of the lines instead of replacing it with antifreeze. It uses no antifreeze (saving $15–$25 and avoiding the pink staining some people dislike), but requires an air compressor and is less forgiving — any water left behind will freeze.
Connect an RV blowout plug (a $5–$10 fitting at Camping World) to your city water inlet. Connect your compressor (regulated to 30–50 PSI). Open each faucet one at a time — starting closest to the inlet — and hold until only air flows. Move to each fixture in the same order as the antifreeze method. After blowing out all fixtures, add 1–2 cups of antifreeze to each P-trap drain as a safety measure since air blowout can't fully protect P-traps.
Which Method Should You Use?
| Antifreeze Method | Compressed Air Method | |
|---|---|---|
| Cost | $15–$25 | $0 (if you own a compressor) |
| Equipment needed | Pump converter kit ($5–$15) | Compressor + blowout plug ($5–$10) |
| Protection level | Very high — antifreeze in all lines | High — but P-traps still need antifreeze |
| Risk of incomplete job | Low — pink antifreeze visible in lines | Higher — can't see if all water is removed |
| Spring cleanup needed | Yes — flush antifreeze out before use | Minimal |
| Best for | Most RVers; less experienced | Experienced RVers; warm but wet climates |
Frequently Asked Questions
Most RV owners can winterize their own rig with the antifreeze method — it requires no special tools beyond a pump converter kit (under $15) and 2–3 gallons of RV antifreeze. RV shops charge $75–$150 for winterizing service. Doing it yourself takes 1–2 hours the first time, 45 minutes once you know your rig.
Properly stored RV antifreeze (sealed jug, kept out of extreme heat) remains effective for several years. Leftover antifreeze from last season is fine to use this year — check that the jug is still sealed and the liquid is still pink and clear. Cloudy or discolored antifreeze should be replaced.
First, do not turn on the water pump. Pressurizing lines that may be cracked will cause flooding. Inspect all visible lines for cracks or splits. If no damage is visible, slowly warm the RV interior (electric heat only — no open flame) and let frozen lines thaw naturally. Once fully thawed, turn on the pump at low pressure and check every fixture and line for leaks. If you find damage, shut off the pump and call an RV repair shop.
If the storage space will reliably stay above 32°F all winter, you don't technically need to winterize the water lines. However, you should still sanitize the fresh water tank, drain and treat the black and gray tanks, and disconnect from water supply. A single cold snap in an unheated garage can cause significant damage — when in doubt, winterize.