How to Winterize an RV: A Step-by-Step Big-Rig Checklist

By Calvin Whitlock · Last updated July 7, 2026 · How we built this

TL;DR: Winterizing an RV means getting every drop of water out of the plumbing so nothing freezes, expands, and cracks a line or fitting over the winter. The order is what matters: drain the fresh, gray, and black tanks → drain the water heater (cool and depressurized) → bypass the water heater → clear the lines → pump non-toxic pink RV antifreeze through every fixture → protect the P-traps and toilet → seal it up. Use RV/marine "pink" antifreeze, which is propylene glycol and low-toxicity — not the toxic green or orange automotive stuff, which is ethylene glycol and will wreck your plumbing and poison your water system. Plan on 3–6 gallons of pink for a big rig (more plumbing than a small trailer), and always bypass the water heater first so you're not wasting 6–10 gallons filling the tank. For a 40-foot-plus Big-Rig Friendly rig, there's simply more to do — more line runs, often a second bathroom, bigger tanks, and more low points — so budget the extra time and the extra jug. Below: the full ordered checklist, the tankless-water-heater variant, whether you even need to do this if you live in the rig, and the batteries/tires/exterior work most checklists skip.

I've been living and driving a big rig full-time for years, and I winterize (or partially winterize) more often than most because I chase shoulder seasons into cold country. Here's the honest, in-order version — the way I actually do it, not a spec sheet.

How to read this: These are well-established procedures, but your rig is the final authority. Valve locations, the number of low-point drains, whether you've got a tank or tankless water heater, and how much antifreeze you'll burn all vary by model. Where I give a number — gallons, PSI, pounds — treat it as a range to confirm against your owner's manual, not a guarantee. I'm a full-time RVer, not your rig's service tech: when in doubt, check the manual or call the manufacturer.

How do you winterize an RV?

You winterize an RV by removing all the water from the plumbing system and replacing what you can't drain with non-toxic RV antifreeze, so nothing left inside can freeze and split a line. That's the whole game. Water expands about 9% when it freezes, and a pressurized water line, a P-trap, a pump head, or a water-heater fitting is exactly the kind of sealed space that cracks when the water inside it turns to ice. Winterizing is cheap insurance against a spring full of leaks.

There are two ways to clear the lines: blow them out with compressed air, or pump antifreeze through them. Plenty of people do both — blow out first to push the bulk of the water, then pump antifreeze to protect the traps and any low spots the air missed. That belt-and-suspenders approach is what I use on a big rig, because a long rig has more line and more places for water to pool.

Here's the sequence, start to finish. Do it in this order — draining before you bypass, bypassing before you pump, is the part people get wrong.

1. Drain the fresh, gray, and black tanks

Dump the black tank first, then the gray (the gray water helps rinse your sewer hose), at an approved dump station. Then drain the fresh-water tank via its drain valve. On a big rig these tanks are bigger than on a small trailer — a full fresh tank can be 80–100 gallons — so give it time to actually empty. While you're here, drain the water pump and, if your rig has a water filter cartridge, pull it and toss it (antifreeze will ruin it, and you'd taste it come spring).

2. Drain the water heater — cool and depressurized

Never drain a water heater that's hot or under pressure. Turn it off, let it cool, then release the pressure by opening a hot faucet inside. Now pull the drain plug (or open the drain valve) and open the pressure-relief valve on the heater to let air in so it glugs out fully. Big-rig water-heater tanks are commonly 6 or 10 gallons — that's 6–10 gallons of antifreeze you'd otherwise waste, which is exactly why the next step matters.

3. Bypass the water heater

Find the bypass valves on the water lines behind the heater (or, on some rigs, under a nearby cabinet) and set them to bypass. This routes antifreeze around the empty water-heater tank instead of filling it. Skip this step and you'll pump gallons of pink straight into the tank you just drained — a waste of antifreeze and a mess to flush out later. If your rig didn't come with a bypass kit, it's a cheap, worthwhile add.

4. Open the low-point drains and clear the lines

Open the low-point drain valves (usually a pair of colored caps or pull-valves under the rig — hot and cold) and open every faucet, high and low, to let the lines gravity-drain. If you're blowing out the lines, this is where you hook a blow-out plug to the city-water inlet and push regulated compressed air through, going faucet by faucet until only air comes out. Keep the pressure low: most guidance lands around 30–40 PSI, and manufacturers like Keystone advise no more than about 30 PSI — RV plumbing takes water pressure fine but air is harder on it, so use a regulator and don't crank it. Blowing out is about volume, not force. On a big rig with long runs, work methodically; there's more line to clear than you think.

5. Pump antifreeze through every fixture

Close the low-point drains and faucets. Set your water pump to draw from the antifreeze jug (via a winterizing kit / siphon hose, or by pouring pink into the fresh tank if you don't have the bypass-to-jug setup). Then open one fixture at a time, starting with the one closest to the pump, until pink runs out steadily — then close it and move to the next. Hit every fixture: kitchen, both bathrooms if you've got them, the outside shower, the washer inlet, the icemaker line, the toilet(s). This is the step where big-rig owners get caught out: forget the second bathroom or the exterior shower and that's your one cracked line in March. Don't forget to run pink until it's visible at each spot.

6. Protect the P-traps and toilet

Pour a cup or so of RV antifreeze down each sink and shower drain to fill the P-traps (the U-bends that hold water to block sewer gas), and into the toilet bowl and holding tank so seals stay lubricated and the trap water doesn't freeze. A splash in each is enough.

7. Seal it up

Close the faucets, reinstall the water-heater drain plug and the low-point caps you opened, and shut the water-heater bypass back to its normal position for storage if your manual calls for it. That's the plumbing done. Total pink used on a typical big rig runs 3–6 gallons with the water heater bypassed — more if you skipped the bypass, more again if you have two baths and a washer.

Is RV antifreeze toxic?

No — the pink RV/marine antifreeze you use for winterizing is propylene glycol, which is low-toxicity and considered safe to run through a potable-water system. That's the whole reason it exists. It's a completely different chemical from the toxic automotive antifreeze (the green, orange, or yellow stuff), which is ethylene glycol — that one is genuinely poisonous, and you must never put it anywhere near your RV's fresh-water plumbing.

Two things are true at once here, so let me be precise:

• RV pink antifreeze (propylene glycol) is low-toxicity and formulated for plastic and rubber plumbing — it even lubricates the toilet seal. It's the correct product. Propylene glycol turns up in tiny amounts in some foods and cosmetics, which is why it's the "non-toxic" choice.
• "Low-toxicity" is not "drink it." RV antifreeze isn't a beverage, and in quantity it can make people and especially pets sick, so store it sealed and flush and sanitize your fresh-water system before you use it again in spring. Low-toxicity means it won't destroy your plumbing or leave a poisonous residue the way ethylene glycol would — not that it's food.

The mistake that costs people a plumbing system: grabbing automotive antifreeze because it's in the garage. Ethylene glycol is corrosive to RV plastic and rubber and toxic in the water lines. Pink only. If the jug doesn't say it's safe for RV/marine potable-water systems, it doesn't go in your rig.

How do you winterize a tankless (on-demand) RV water heater?

A tankless or on-demand RV water heater winterizes a little differently: there's no 6–10 gallon tank to drain, but there's a small internal water path and often a filter that must be drained or removed, and you follow the manufacturer's specific procedure rather than the tank-heater routine. More big rigs run these now (Truma AquaGo, Girard, and similar), so this variant matters.

The general shape, using the common Truma AquaGo as the example:

1. Turn the unit off and let it cool completely.
2. Depressurize — turn off the pump or incoming water and open all the hot and cold fixtures.
3. Set it to bypass per the manufacturer's instructions (Truma's bypass valves are typically under a nearby cabinet).
4. Drain the unit. On the AquaGo you swing the yellow "Easy Drain Lever" down, which empties the mixing vessel and ejects the filter cartridge. Store that filter separately over the winter.
5. Some tankless units can be fully winterized by draining alone, no antifreeze needed in the heater itself — Truma advertises exactly that for the AquaGo. You'll still run pink through the rest of your fixtures and traps.

The catch: procedures genuinely vary by brand and model year, more than they do for a standard tank heater. Don't assume your on-demand unit works like the AquaGo. Pull up your specific model's winterizing instructions in the manual before you drain anything — this is the one component where guessing can crack an expensive part.

Do you need to winterize your RV if you live in it?

If you're living in the rig and keeping it heated through the winter, you generally don't do a full antifreeze winterize — a system full of pink antifreeze is unusable, and you can't live without running water. Instead you shift to cold-weather use: keep the interior heated, protect the exposed plumbing, and only winterize if you're going to leave it cold and unoccupied. Winterizing and living aboard are two different modes.

Here's the honest breakdown for a full-timer in cold country:

• Staying and heating the rig? Don't fill the lines with antifreeze. Keep the furnace running (the belly/underbelly on a four-season big rig is usually heated by ducted furnace air), use the tank heating pads if you've got them, heat-tape or insulate the exposed hose and the city-water connection, and lean on your fresh tank with the internal pump on the coldest nights instead of a frozen city hose. A genuinely four-season big rig with an enclosed, heated underbelly handles this well; a three-season rig needs more babysitting.
• Leaving it cold — even for a week or two of travel, or if the furnace could fail? Then winterize it properly, or at minimum blow out the lines. A power outage or a dead furnace with the rig full of water is how full-timers come home to burst pipes.
• Somewhere in between — parked but occupied, mild-cold climate — a lot of full-timers do a partial: drain and bypass the water heater, keep the cabin warm, and protect the traps. Match the effort to how cold it actually gets and how reliable your heat is.

So the real answer to "do I need to winterize if I live in it" is: not if you're keeping it warm and occupied — but have a cold-weather plan, because the risk isn't the calendar, it's an unheated rig full of water.

What about batteries, tires, and the exterior?

Winterizing isn't only plumbing — if the rig is going into storage, the batteries, tires, and exterior need attention too, or you'll trade a cracked pipe for a dead battery and flat-spotted tires. This is the part the plumbing-only checklists skip, and on a heavy big rig it's the part that costs real money.

• Batteries. Parasitic loads (clocks, detectors, propane sensors, control boards) will slowly drain a battery all winter, and a discharged battery can freeze and be ruined. Either flip the main battery disconnect, or in hard-freeze country pull the batteries and store them somewhere dry and above freezing on a maintainer. Lead-acid batteries store best fully charged (a charged battery resists freezing); lithium (LiFePO4) stores best around a partial charge and, note, most lithium BMS units stop charging below about 32°F — so don't count on charging them in a frozen bay. Check them periodically.
• Tires. Big-rig tires are expensive and heavy-loaded. Inflate to spec, and if you can, get the weight off them or put a barrier (boards) under each to fight flat-spotting during a long sit. UV/tire covers matter if the rig sits outside — sun and ozone age sidewalls even in winter.
• Exterior and the rest. Reseal any roof/seam gaps before the wet season (water intrusion is the true rig-killer, especially on a big rig with a large roof), cover or park smart to keep snow load and UV off, add roof-vent covers, and toss moisture absorbers or a low-draw dehumidifier inside to fight interior condensation. Pull perishables and anything that can freeze-and-burst (canned drinks, that bottle of water in the door).

None of this is exotic — it's just more of it on a big rig, because there's more roof, more tire, more battery bank, and more square footage of interior to keep from turning into a damp, moldy box by spring.

Quick answers RVers also ask

How do you winterize a motorhome specifically?

Same plumbing sequence as any RV — drain tanks, drain and bypass the water heater, clear the lines, pump pink through every fixture, protect the traps — plus the chassis side a motorhome adds. Because a motorhome has an engine, if it's going into long storage also think about the engine and generator: full fuel tank with stabilizer, fresh oil where the interval calls for it, and run or properly store the generator per its manual. A towable trailer skips all of that. The water system, though, winterizes identically.

How much does a gallon of RV antifreeze weigh?

Roughly 8.3 to 8.6 pounds a gallon — a hair heavier than water, which is about 8.34 pounds a gallon. Treat that as a ballpark; the exact figure varies a little by formula and temperature, and jugs are usually sold in gallon sizes. It matters mostly for two reasons: buying enough (a big rig may need 3–6 gallons, so that's a 25–50 lb armful) and remembering that any antifreeze you leave sitting in a tank is weight you're hauling — one more reason to bypass the water heater rather than fill it.

Can you use regular automotive antifreeze to winterize an RV?

No. Automotive antifreeze is ethylene glycol — toxic, and corrosive to the plastic and rubber in RV plumbing. It will contaminate your fresh-water system and can damage seals and lines. Use only pink RV/marine antifreeze (propylene glycol), which is made for potable-water plumbing. There is no shortcut here worth a poisoned water system.

Do you have to use antifreeze, or can you just blow out the lines?

You can winterize with compressed air alone, and many people do — but blow-out doesn't protect the P-traps, and it can miss low spots in a long rig's plumbing. The safest approach on a big rig is both: blow out the bulk of the water, then pump a little antifreeze to fill the traps and backstop anything the air didn't clear. If you go air-only, still pour pink into every drain trap and the toilet.

How we built this

This guide lays out the standard RV winterizing sequence and reads it through a big-rig lens — because a 40-foot-plus rig has more line runs, often a second bathroom, bigger fresh and holding tanks, and more low points than the small trailer most checklists are written for, so there's simply more to drain, more fixtures to reach, and more antifreeze to budget.

I write from years of full-time big-rig RVing — I winterize and cold-camp more than most because I chase shoulder seasons into freezing country — so the sequence, the "don't forget the second bathroom" warnings, and the live-in-it-vs-store-it call are first-hand. I'm a full-time RVer, not your rig's service technician or its manufacturer — where a number is a range (gallons of antifreeze, blow-out PSI, antifreeze weight) I've said so rather than inventing a precise figure, and I point you to your owner's manual for valve locations and model-specific steps, especially on tankless water heaters where procedures really do differ. Research and drafting for this page were AI-assisted and reviewed by a human (me) before publishing. No brand paid for a mention here, and nothing on this page was written to sell you a product.

Sources (last verified July 2026):

• Keystone RV — How to Winterize Your RV with Antifreeze and …with Compressed Air (procedure, blow-out PSI guidance): keystonerv.com
• Camping World — Everything You Need to Know About RV Antifreeze and How To Winterize an RV Tankless Water Heater: blog.campingworld.com
• Truma — Time to Winterize: Truma AquaGo (tankless drain/bypass procedure): truma.com
• RV LIFE — How Much RV Antifreeze Do I Need? and RV Antifreeze: Not All the Same (quantities, propylene vs. ethylene glycol): rvlife.com
• etrailer / RV Trader — RV antifreeze facts (propylene glycol, low-toxicity): etrailer.com, rvtrader.com

Verification status (last verified July 2026): The winterizing sequence and the propylene-glycol (RV/pink, low-toxicity) vs. ethylene-glycol (automotive, toxic) distinction are cross-checked against the manufacturer and RV-service sources above. All quantities — antifreeze gallons, blow-out PSI, gallon weight, water-heater tank size — are stated as ranges because they vary by rig and are not asserted as universal specs. Model-specific steps, especially for tankless water heaters, are deferred to each reader's owner's manual by design. No fabricated figures appear on this page.

Frequently asked questions

How do you winterize an RV?

Drain the black, gray, and fresh tanks; drain the water heater once it's cool and depressurized; set the water-heater bypass; open the low-point drains and clear the lines (blow them out with regulated air at roughly 30 PSI and/or pump antifreeze); then run non-toxic pink RV antifreeze through every fixture until it flows out, and pour some into each P-trap and the toilet. Reinstall the drain plugs and caps. Do it in that order — drain before you bypass, bypass before you pump. A big rig usually takes 3–6 gallons of pink with the water heater bypassed.

Is RV antifreeze toxic?

No — RV/marine "pink" antifreeze is propylene glycol, which is low-toxicity and safe to run through a potable-water system; that's why it's used for winterizing. It's a different chemical from automotive antifreeze, which is ethylene glycol and genuinely poisonous. "Low-toxicity" doesn't mean drink it — it can still make people and especially pets sick in quantity, so store it sealed and flush and sanitize your fresh-water system in spring. Never use automotive antifreeze in RV plumbing; it's toxic and corrodes plastic and rubber.

How do you winterize a tankless RV water heater?

Turn the unit off and let it cool, depressurize by opening the fixtures, set it to bypass, and drain it per the manufacturer's instructions — on a Truma AquaGo you drop the yellow Easy Drain Lever, which empties the unit and ejects the filter cartridge to store separately. Some tankless units, including the AquaGo, can be fully winterized by draining alone with no antifreeze in the heater itself. Procedures vary by brand and model year more than tank heaters do, so follow your specific unit's manual.

Do I need to winterize my RV if I live in it?

Not with a full antifreeze winterize if you're keeping the rig heated and occupied — a system full of pink is unusable, and you need running water. Instead, run the furnace, use tank heating pads, insulate or heat-tape the exposed hose and city-water connection, and lean on the fresh tank and internal pump on the coldest nights. Do winterize (or at least blow out the lines) any time you'll leave the rig cold and unoccupied, since a power outage or furnace failure with the lines full of water is what bursts pipes.

How do you winterize a motorhome?

The plumbing steps are identical to any RV — drain the tanks, drain and bypass the water heater, clear the lines, pump pink through every fixture, and protect the traps. A motorhome adds the chassis side if it's going into long storage: fill the fuel tank and add stabilizer, keep up with engine oil, and run or store the generator per its manual. A towable trailer skips the engine and generator steps entirely.

How much does a gallon of RV antifreeze weigh?

About 8.3 to 8.6 pounds a gallon — just slightly heavier than water at roughly 8.34 pounds a gallon. The exact number varies a little by formula and temperature. It's worth knowing when you buy: a big rig may need 3–6 gallons, so that's a 25–50-pound armful, and it's one more reason to bypass the water heater rather than fill a 6–10 gallon tank with antifreeze you'd only have to haul and flush.

Compare across the directory: What "Big-Rig Friendly" means (the standard behind every score) · RV Rules Explained (the 3-3-3, 10-year, and 80/20 rules through a big-rig lens) · Can You Live in an RV? (the full-time and cold-weather-living reality) · RV Weight Explained (GVWR, tanks, and why every gallon aboard counts). Winterizing is the seasonal chore; those pages cover how a big rig travels, parks, and lives the rest of the year.

[ Submit a correction → ]   Do a step differently, run a tankless unit I didn't cover, or winterize a big rig with quirks worth adding? Tell me and I'll update the checklist.