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How to Winterize an RV Water System: Drain, Bypass and Antifreeze

Updated October 31, 2026 · General information, not plumbing or legal advice

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The short answer: Drain the fresh tank, lines and water heater, bypass the water heater, then pump RV-approved non-toxic antifreeze through every faucet and drain. Never use automotive antifreeze. This page covers the water system only. Your owner's manual wins over any general guide, including this one.

Safety first. Never thaw a pipe with a torch or any open flame. They are a fire hazard and can release deadly carbon monoxide. Keep electrical cords away from water, and stay out of rooms where water is near outlets, panels or appliances.

Steps (Keystone RV and KZ RV)

Open the low-point drains and all faucets, including the outside shower if you have one, and empty the freshwater tank through its drain valve (Keystone RV).
Drain the water heater. Turn it off in both gas and electric modes, then remove the drain plug and open the pressure relief valve (Keystone RV). KZ RV says to confirm the heater hasn't run in the last 24 to 48 hours, and its page has model steps such as removing the anode rod. Tankless units need the maker's procedure (Keystone RV).
Set the water heater bypass valves on the lines entering the back of the heater to the bypass position, so antifreeze stays out of the tank (Keystone RV, KZ RV).
Remove the water filter cartridge and drain the filter base (Keystone RV).
Connect the antifreeze. With a pump bypass, connect the bypass hose to the antifreeze jug. Without one, close the freshwater tank drain valve and pour antifreeze into the tank (Keystone RV).
Run the pump until antifreeze reaches each faucet, cold side then hot side (Keystone RV). KZ RV says to start with the faucet closest to the pump.
Protect the drains. Pour about one quart into each drain and P-trap and the toilet (Keystone RV). KZ RV says one pint per drain. Flush the toilet and leave some antifreeze in the bowl to protect the seals (Keystone RV).
Run the washer cold and hot cycles until antifreeze appears, if you have one. Do not add antifreeze to a residential refrigerator's ice maker line; drain it (Keystone RV).
Close the valves and reinstall caps and plugs to keep pests out (Keystone RV).

Different makers, different amounts. Keystone RV and KZ RV give different quantities. Neither is wrong for its own RV. Follow your own manual.

Protect the pipes at home too

Pipe sleeves and UL-listed heat cable are the products Red Cross and extension services point to for exposed pipes. Read the label and follow the maker's instructions.

How to choose and use them See pipe insulation and faucet covers See UL-listed heat cable

Related guides

Common questions

What kind of antifreeze do I use in an RV?

Keystone RV says to use RV-approved, non-toxic antifreeze and never automotive antifreeze, which is toxic and unsafe for potable water systems. KZ RV also says to use non-toxic antifreeze.

How much antifreeze does it take?

It varies. Keystone RV says at least 4 to 6 gallons. KZ RV says two gallons or more, depending on tank sizes. Check your owner's manual.

Should antifreeze go in the water heater?

No. KZ RV says it's important that no antifreeze gets into your water heater, and Keystone RV says to set the bypass valves to the bypass position. Not every RV has a bypass; KZ says the kit is standard on some models and optional on others.

Can I drink the water after winterizing?

Not with antifreeze in the lines. KZ RV: "Do not drink water that contains antifreeze."

Sources