10 Common RV Winter Prep Mistakes (and How to Fix Them Before It’s Too Late)

When fall rolls around, it’s time to think about parking the RV for winter. Unfortunately, a lot of owners either rush through winterizing or skip a few key steps—and that’s when expensive damage happens. 

Freezing water lines, ruined seals, cracked fittings, or even a burst water heater tank can all result from simple mistakes. The good news? With the right prep, you can avoid them all. 

Here’s a detailed look at the most common winterizing errors RV owners make—and how to prevent them so your rig stays road-ready for spring. 

Why Winterizing Is More Than Just Draining the Tanks 

When temperatures drop below freezing, any water left in the plumbing, tanks, or appliances can expand and split fittings, burst lines, or crack tanks. 

But water isn’t your only concern. Batteries can lose charge and freeze, tires can develop flat spots, and even the seals and roof seams can deteriorate if left unchecked. Mold, pests, and bad odors can creep in too. 

Taking the time to properly winterize your RV ensures you’ll have fewer headaches, no surprise repair bills, and a smooth start when it’s time to hit the road again. 

1. Forgetting to Drain and Bypass the Water Heater 

A water heater full of water can crack if it freezes—and a ruptured tank is one of the priciest repairs on any RV. Some owners remember to drain but forget to bypass, wasting gallons of antifreeze. Others bypass but forget to drain first, leaving water to freeze inside. 

How to do it right: 

  • Make sure the water heater is off and cooled down before draining. 
  • Turn off the 120V breaker or power switch for the water heater to avoid burning out the element. 
  • Open the drain plug and pressure relief valve to completely empty the tank. 
  • Use the bypass valve to divert antifreeze away from the heater. 
  • For tankless heaters, some manufacturers recommend running antifreeze through the unit since they’re harder to drain fully. 
  • Once done, leave both the drain and relief valve open during storage to ensure no water remains inside. 

2. Not Clearing All Water Lines 

Even after draining tanks, small amounts of water can remain trapped in the plumbing—especially at low points or in outdoor showers and ice makers. When this water freezes, it can easily crack lines and fittings. 

Best practice: 

  • Use an air compressor (around 40 PSI) to blow out all water lines. 
  • Open every faucet, drain, and valve while blowing out the system. 
  • Don’t forget hidden lines: outside showers, ice makers, and filtered water taps often get overlooked. 
  • After blowing out, many RVers also pump RV antifreeze through the system for added protection. 
  • Leave low-point drains open and faucets slightly open so any condensation can escape. 

Extra tip: 

 Keep the toilet flush valve slightly open with a stick or heavy shoe—this prevents trapped water from damaging the valve. And before storage, clean and deodorize your black tank to avoid springtime odors. 

3. Using the Wrong Antifreeze 

This one’s simple but serious: automotive antifreeze is toxic and never safe for RV plumbing systems. It can poison water lines, damage fittings, and is hazardous to humans and pets. 

Solution: 

Only use RV/marine antifreeze labeled as non-toxic and safe for potable water systems. It’s specially designed to protect pipes without leaving harmful residue and flushes out easily in spring. 

4. Forgetting the Water Pump and Holding Tanks 

It’s easy to focus on pipes and faucets, but the water pump and holding tanks need attention too. Any moisture left in these areas can freeze, cracking valves or internal seals. 

To prevent this: 

  • Run the water pump until it’s dry or circulate RV antifreeze through the entire system. 
  • Pour a cup or two of RV antifreeze into the gray and black tanks to protect the dump valves. 
  • If you’re not using antifreeze, set up a drop light with a 60-watt incandescent bulb near the water pump to provide mild warmth (make sure it’s in a protective cage and not touching anything flammable). 

5. Skipping Exterior and Roof Maintenance 

Even a small crack or worn seal can let in water during the freeze-thaw cycle, causing rot, mold, or delamination. Many owners skip this step—and regret it later. 

What to check: 

  • Examine all window, roof, and vent seals for cracks or peeling. 
  • Apply RV-grade sealant where needed. 
  • Check roof seams and repair weak spots. 
  • Use a breathable RV cover or, better yet, store indoors under a carport or in a garage. 

6. Ignoring Battery Maintenance 

RV batteries—especially lead-acid types—can lose their charge in cold storage. If fully discharged, they can freeze and crack. Replacing them isn’t cheap. 

What to do: 

  • Disconnect batteries and store them in a dry, heated space. 
  • Keep them at about 50–80% charge and check monthly. 
  • Use a trickle charger or battery maintainer for long storage periods. 
  • Clean terminals and coat with dielectric grease to prevent corrosion. 
  • For lithium batteries, follow manufacturer storage recommendations—some shouldn’t be charged below freezing temperatures. 

7. Overlooking Tire Care 

When an RV sits for months, tire pressure drops and flat spots can form. Cold weather only makes it worse. 

How to avoid damage: 

  • Inflate to the recommended PSI before storage. 
  • Move the RV occasionally to redistribute weight. 
  • Use tire blocks or pads to prevent direct contact with frozen ground. 
  • Add tire covers to protect from UV rays and ice. 

8. Leaving Food or Organic Debris Inside 

Even “non-perishables” can attract pests, and canned goods can split in freezing conditions. Once rodents find their way in, they can chew wires, insulation, and fabric. 

Prep checklist: 

  • Remove all food, including canned, boxed, and sealed items. 
  • Vacuum and wipe all surfaces to remove crumbs. 
  • Clean out drawers, cabinets, and the fridge. 
  • Place rodent traps or natural repellents like peppermint oil packs to deter intruders. 

9. Closing the RV Too Tightly 

Sealing your rig airtight might seem smart—but it traps moisture and leads to condensation, mildew, and a musty smell. 

Simple fix: 

Install vent covers that let your RV breathe while keeping rain and snow out. Crack windows slightly if stored indoors to promote airflow and reduce humidity. 

10. Waiting Too Long to Get Started 

Procrastination is one of the most expensive winterizing mistakes. Just one unexpected freeze can burst pipes before you’ve even pulled out the antifreeze. 

Avoid the rush: 

  • Start winterizing in early to mid-fall, even if you plan one last trip. 
  • If a warm weekend comes up, you can always de-winterize temporarily. 
  • In case of an early cold snap, get to your RV fast—turn on interior heat, and if equipped, use tank heaters and the water heater to protect plumbing. 

Keep Your RV Safe All Winter 

Winter prep doesn’t have to be stressful—it just needs to be thorough. From draining your water heater to sealing the roof, each small step protects your rig from damage and costly repairs. 

Follow these guidelines, and when spring returns, your RV will be clean, dry, and ready for another season of adventure.