How to Winterize RV Plumbing: Complete Freeze Protection Guide

A single night of subfreezing temperatures can turn water inside your RV's plumbing system into ice — and ice expands with enough force to crack pipes, burst water heaters, and destroy pump seals. Winterizing your RV's plumbing system is the single most important seasonal maintenance task for anyone who camps in cold climates or stores their rig through winter. Done properly, winterization takes about an hour and costs less than $30. Done poorly — or not at all — it can result in thousands of dollars in freeze damage.

When to Winterize Your RV

The simple rule: winterize before the first hard freeze of the season. A hard freeze is defined as temperatures at or below 28°F for at least four hours. Even if daytime temperatures stay above freezing, overnight lows in the high 20s are enough to freeze water lines, especially in exterior compartments and unheated basement bays.

If you're actively camping through fall and winter, you don't necessarily need to fully winterize — but you do need to manage your water system aggressively. Use tank heaters, heated water hoses, and skirting to protect your plumbing during use. For storage or extended periods without use in freezing climates, full winterization is non-negotiable.

Two Methods: Compressed Air vs. RV Antifreeze

There are two primary approaches to winterizing RV plumbing. Most experienced RVers use a combination of both methods for maximum protection.

Method 1: Compressed Air (Blow-Out Method)

This method uses an air compressor to blow all water out of your fresh water lines. It's faster and uses no chemicals, but it doesn't protect your holding tanks or P-traps (the curved drain pipes under sinks that hold standing water).

Advantages: No antifreeze taste in water lines come spring, no chemicals to flush out

Disadvantages: Doesn't protect tanks or drain traps, requires an air compressor

Method 2: RV Antifreeze

This method uses non-toxic RV antifreeze (the pink stuff, never automotive antifreeze) to displace all water in the system. It protects everything — water lines, tanks, drains, and traps.

Advantages: Complete system protection, protects holding tanks and drains

Disadvantages: Requires flushing the system before use in spring, slight taste in water lines until fully flushed

Step-by-Step: Full Winterization Using RV Antifreeze

Step 1 — Drain All Tanks and Lines

Before adding antifreeze, you need to remove as much water as possible from the system:

• Empty your fresh water tank completely using the low-point drain valve
• Dump your black and gray holding tanks at a dump station (use our dump station finder to locate one near you)
• Open all hot and cold faucets inside the RV and let them run until water stops flowing
• Flush the toilet until the bowl is dry
• Drain the water heater by opening the drain valve and removing the pressure relief valve. Let it drain completely — this takes 10 to 15 minutes for a 6-gallon heater.

Step 2 — Bypass the Water Heater

Most RVs have a water heater bypass valve system. Locate the bypass valves (usually on the back of the water heater or in a nearby compartment) and turn them to the "bypass" position. This prevents antifreeze from filling your water heater — saving you 6 to 10 gallons of antifreeze and preventing contamination of the heater's potable water.

If your RV doesn't have a factory bypass, you can install an aftermarket kit for about $15. Brands like Camco and Shurflo make universal bypass kits that work with most water heaters.

Step 3 — Prepare the Antifreeze Pump

You'll need 2 to 3 gallons of RV antifreeze (look for non-toxic propylene glycol rated to at least -50°F). Pour the antifreeze into a bucket or container.

Locate your RV's water pump and find the inlet line that normally draws from the fresh water tank. Most RVs have a valve or quick-disconnect that lets you switch the pump's intake from the fresh water tank to an external source. Disconnect the inlet line from the tank and place the end into your bucket of antifreeze. If your RV doesn't have this feature, you can install a winterizing kit that includes a T-valve and hose specifically for this purpose.

Step 4 — Pump Antifreeze Through the System

Turn on your RV's water pump. Starting with the faucet closest to the pump, open the cold water tap and let it run until you see pink antifreeze flowing steadily. Then close the cold tap and open the hot tap until pink antifreeze flows. Repeat this process for every faucet, shower, and water outlet in the RV — including:

• Kitchen sink (hot and cold)
• Bathroom sink (hot and cold)
• Shower (hot and cold)
• Outside shower (if equipped)
• Toilet (flush until the bowl and lines show pink)
• Ice maker and washing machine hookups (if equipped)

Don't forget exterior outlets like the outdoor kitchen or shower. Once pink antifreeze flows from every tap, your water lines are protected.

Step 5 — Protect the Drain Traps

Pour a cup of RV antifreeze down each drain — kitchen sink, bathroom sink, shower drain, and any other drains in the RV. This fills the P-traps (the curved sections of pipe that hold water to prevent sewer gas from entering the living space) with antifreeze, preventing them from freezing and cracking.

Step 6 — Protect the Holding Tanks

Pour a gallon of RV antifreeze into the black tank via the toilet. Flush it down and let it sit in the tank. Pour another gallon down the various sinks and shower drains to protect the gray tank. This prevents any residual water in the tanks from freezing and cracking the tank walls or sensors.

For more on maintaining your holding tanks year-round, see our tank management guide.

Step 7 — Final Checks

• Turn off the water pump
• Close all faucets
• Check exterior compartments for any water filters, inline sediment filters, or water pressure regulators that may still contain water — drain or remove these
• If you use a portable ice maker or washing machine, consult the owner's manual for winterization instructions specific to that appliance

Common Winterization Mistakes to Avoid

• Using automotive antifreeze: Never use automotive antifreeze (green or orange) in an RV fresh water system. It is toxic. Only use RV antifreeze (pink) rated for potable water systems.
• Skipping the water heater bypass: If you don't bypass the water heater, you'll waste 6+ gallons of antifreeze filling it — and you'll contaminate the heater unnecessarily.
• Forgetting exterior outlets: Outdoor showers, exterior spray ports, and washing machine hookups are easy to overlook. Frozen exterior lines are just as expensive to repair as interior ones.
• Leaving water in the tanks: Draining the fresh tank isn't enough — you need to open low-point drains to get water out of the lines as well. Residual water will freeze even if the tank itself is empty.
• Not testing the system in spring: Before your first trip after de-winterizing, run water through all taps and check for leaks. Freeze damage doesn't always show up immediately — cracks can be hairline thin and only leak under pressure.

De-Winterizing in Spring

When temperatures warm up and you're ready to camp again, you'll need to flush the antifreeze from your system:

1. Drain all antifreeze from the system by opening all faucets and the low-point drains
2. Close all drains and faucets
3. Fill the fresh water tank with potable water
4. Turn the water heater bypass valves back to normal operating position
5. Turn on the water pump and run water through every faucet until it runs clear and no longer smells of antifreeze
6. Sanitize the fresh water system using a bleach solution (1/4 cup bleach per 15 gallons of tank capacity), let it sit for 12 hours, then flush completely

Winter Camping vs. Storage Winterization

If you're actively winter camping rather than storing your RV, you don't need to fully winterize — but you do need to manage freeze risk continuously. Use heated water hoses, tank heating pads, and heat tape on exposed pipes. Keep your furnace running overnight even when you're not in the RV. Add skirting around the RV's undercarriage to trap heat. For more on cold-weather dumping and tank management, see our winter dump station guide.