Winterizing an RV means draining the fresh, gray and black tanks and the water heater, bypassing the heater, then either pumping nontoxic RV antifreeze through every line or blowing the lines dry with compressed air, and pouring antifreeze into each drain trap and the toilet.
How to Winterize an RV: The Antifreeze and Blow-Out Methods, Step by Step
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At a glance
- When: Jayco, Winnebago and Grand Design all say to winterize before the RV sees 32°F (0°C), and Jayco adds that freeze damage is not covered by warranty.
- Two methods: RV antifreeze (wet) or compressed air (dry); Jayco calls antifreeze the preferred method and Airstream says many owners do both.
- Bypass the water heater: it keeps the 6 or 10 gallon tank from swallowing several gallons of antifreeze.
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How to winterize an RV, step by step
These are the steps the builders' manuals share. Where your own RV's manual differs, follow it: it is written for the valves you actually have.
For the antifreeze method, plan on 4 to 6 gallons of nontoxic RV antifreeze, as Keystone's 2027 owner's manual and Forest River's travel trailer and fifth wheel manual both say. Less if you blow the lines out first.
- Switch the water heater off, gas and electric, and let the water cool.
- Level the RV, drain the fresh water tank and open the low point drains. On a Jayco, labels on the sidewall mark where they are.
- Dump the gray and black tanks at a proper dump facility.
- Lift the pressure relief valve lever, then remove the water heater drain plug. On a Suburban tank the anode rod is the drain plug and takes a 1-1/16 inch socket. Never pull the plug while the heater is hot or under pressure: the water scalds.
- Set the water heater bypass valves to the bypass position.
- Take the cartridge out of a canister water filter and leave the housing empty. Jayco and Keystone both warn that antifreeze ruins the cartridge.
- Close the fresh tank drain and the low point drains and refit the heater drain plug, so the pump can pull suction.
- Feed the pump from the antifreeze jug, through a siphon valve and hose at the pump, an EZ winterizing port, or a bypass hose on the pump's suction side. Camco's hand pump kit instead pushes antifreeze in through the city water connection.
- Switch the pump on and open one fixture at a time, highest to lowest, until antifreeze runs steadily. Include the outside shower, an outside kitchen and the washer hookups.
- Hold the toilet lever until antifreeze runs into the bowl.
- Pour antifreeze into each drain trap and down the toilet (amounts below).
- Pump off, siphon valve back to normal, and wipe the antifreeze out of the sinks, shower and toilet so it does not stain.
Tip: Never run the pump dry for long. Jayco's 2027 towable manual says 15 to 20 seconds; Keystone says about 30 seconds and warns that longer can damage the pump.
Antifreeze or blowing out the lines?
Air pushes out the water left after draining; antifreeze replaces it. Jayco prefers antifreeze because it needs no compressor, and Airstream says owners who keep camping in the cold often blow the lines out first, then cycle antifreeze through.
For the air route, do steps 1 to 6 above, open the drains and taps, run the pump briefly to clear its suction line, fit a blow out plug to the city water inlet and let the compressor push the lines dry, usually 5 to 10 minutes. The traps and toilet still need antifreeze.
One hard rule from Jayco: never apply air pressure with a valve, faucet or low point drain closed. Pressure against a closed valve can damage seals and cause leaks.
Where builders disagree
Check your own manual on these four steps before you start.
| Step | What builders say |
|---|---|
| When to drain the water heater | First, before filling the lines (Jayco, Keystone, Forest River, Winnebago). Camco's guide says not to drain it until the pipes are filled with antifreeze, with the heater bypassed. |
| Air pressure for blowing out lines | Around 20 lbs psi (Winnebago); 30 PSI (Jayco, Keystone, Forest River, Grand Design); 40 PSI maximum on the Nautilus P4 sheet bound into Grand Design's manual; under 60 psi (Airstream). |
| Antifreeze in the fresh water tank | Never (Jayco, which siphons past the tank). A gravity fill into the tank is one accepted route (Keystone, Forest River). |
| Bypass setting for the air method | Normal, so air passes through the heater (Jayco). Bypass (Keystone, Forest River). |
Sources: Winnebago 2026 towables manual, Grand Design Momentum fifth wheel manual and Airstream's winterizing guide.
Does antifreeze go in the water heater?
No. Every builder sets the bypass valves so the tank stays out of the loop. On a tank water heater the bypass valves sit behind the unit.
Suburban adds that antifreeze can be very corrosive to the anode rod. With no bypass kit, remove the anode for the winter and fit a 3/4 inch drain plug before adding antifreeze.
Tip: Without a bypass kit, Keystone says you need an additional 6 to 10 gallons of antifreeze, the size of the tanks in Dometic's WH series.
Which antifreeze goes in the lines
Use RV antifreeze only. Camco makes it from propylene glycol, which, Camco says, the U.S. government considers generally safe; that is why Camco sells it for drinking water systems.
Automotive antifreeze (ethylene glycol) and windshield washer antifreeze (methanol) are toxic and potentially fatal if swallowed, and must never go into the fresh water system. Jayco, Keystone, Forest River, Grand Design and Airstream all say so.
Not every RV antifreeze is propylene glycol. Star brite's Winter Tech is alcohol based, and Star brite says to check it is compatible with your water system first.
Toilet, traps, ice maker and washer
Every drain trap needs its own antifreeze; use your manual's amount and leave a little in the toilet bowl so the seals stay wet, as Keystone says.
| Where it goes | Amount | Maker |
|---|---|---|
| Each sink drain P-trap | 1 cup | Jayco |
| Each shower, tub and sink drain | About 1 quart | Keystone |
| All sink and shower drains | At least 2 pints | Camco |
| Toilet, for the black tank | 1 quart | Keystone |
| Toilet and each sink drain, for black and gray | 1 gallon each | Forest River |
Winnebago confirms antifreeze will not harm the plastic holding tanks.
The ice maker is the exception: Keystone says to switch it off and drain its line, with no antifreeze in it. For a dishwasher or washing machine, Camco and Jayco send you to the appliance manual.
Tankless heaters and the water pump
Follow the heater maker, because these instructions conflict.
| Heater | What the maker says |
|---|---|
| Truma AquaGo | Drain it and separate it from the water system with a bypass; winterizing fluid is only possible with a bypass kit fitted. |
| Truma AquaGo in a Jayco Class C | Do not blow the unit out with air; Jayco says it may damage the appliance. |
| Girard GSWH-2 | Either compressed air or nontoxic antifreeze, and no bypass kit is needed. |
| Suburban ST tankless | Compressed air is the preferred purge, at no greater than 40 PSI. |
| Fogatti, in Grand Design Momentum | Grand Design recommends not bypassing the unit while winterizing. |
Sources: Truma's AquaGo instructions, Girard's GSWH-2 manual, Suburban's ST-42/ST-60 manual and the Grand Design manual above.
For the water pump, Shurflo and Remco describe draining rather than pumping antifreeze: run the pump with the taps open until it purges, disconnect the inlet and outlet fittings and leave them off. Remco adds that antifreeze deteriorates its pump parts, so rinse the pump with fresh water.
De-winterizing in spring
Fill the fresh tank, run the cold side of every fixture, then the hot side, and flush the toilet. Star brite says to flush for 15 to 20 minutes until no color shows. Dump the tanks, sanitize with household bleach as your builder specifies, and fit a fresh filter cartridge.
Then turn the water heater bypass valves back to normal and let the tank fill before you light it: Keystone warns that lighting an empty heater can damage it. If there is no hot water after storage, check for a bypass valve left in the winter position first.
Common questions
At what temperature does RV antifreeze freeze?
Camco says its -50 RV antifreeze starts forming ice crystals around +10°F and looks like solid ice around -10°F to -15°F. It does not expand enough to burst pipes until -50°F, the figure on the label. Star brite explains the same difference.
Can I pour RV antifreeze down the drain?
Yes, into the RV's own drains and toilet; that is how builders protect the traps and toilet seals. If some spills on a driveway or grass, Camco says to hose the area thoroughly with water.
Do I put RV antifreeze in the fresh water tank?
Only if your builder's method calls for it. Keystone and Forest River fill the tank by gravity above the pump's minimum level, while Jayco keeps antifreeze out of the tank entirely.
Is blowing out the lines enough to winterize an RV?
Not on its own, because air cannot empty a drain trap or protect the toilet seals. Camco also notes that water left by an incomplete blow out dilutes any antifreeze that follows.