RV Winterization 101: A Step-by-Step Guide for Montana’s Climate

Water left in an RV’s plumbing, water heater, or holding tanks will freeze and expand — and expanding water cracks pipes, fittings, and tanks with enough force to cause damage that’s expensive to find and fix. In the Flathead Valley, where hard freezes typically arrive well before winter officially does (Glacier’s Going-to-the-Sun Road, for reference, closes for the season each fall and doesn’t fully reopen until roughly June or July), it’s worth winterizing earlier than you might think.

The general sequence

1. Drain everything. Empty the fresh water tank, and drain the gray and black tanks completely.
2. Bypass the water heater. Most RVs have a bypass valve so you don’t waste antifreeze filling a tank you’re about to drain anyway. Drain and, if you have one, remove the water heater’s anode rod for inspection.
3. Clear the lines. Either blow compressed air through the water lines to push out remaining water, or pump RV-specific antifreeze through the system until it runs pink at every faucet, the shower, the toilet, and each drain’s P-trap.
4. Protect the batteries. Follow your battery manufacturer’s guidance on storage — many recommend disconnecting or removing batteries and keeping them somewhere temperature-stable rather than left in an unheated rig all winter.
5. Check the roof and seals. Do this before the snow starts, not after — a small gap around a vent or seam is a minor fix in October and a much bigger one after a winter of freeze-thaw cycles finds it first.
6. Shut off propane and seal up entry points that rodents use to get in over winter.

Related: your tires don’t get a pass just because the RV isn’t moving — RV tires age even in storage, so consider covering them or using tire covers to reduce sun and ozone exposure over winter.