Your RV is Leaking: A Step-by-Step Guide to Finding & Fixing the Source

Understanding the Enemy: The Usual Suspects of RV Leaks

1. The Roof: Public Enemy #1

• Deteriorated Sealant: The lap sealant used around every opening on your roof is the first line of defense. Over time, UV rays & weather make it brittle, causing it to crack & pull away.
• Physical Damage: Low-hanging tree branches, hail, or even accidental damage from walking on the roof can create punctures or tears in the roof membrane.
• Aging Roof Membrane: Whether you have a rubber (EPDM/TPO) or fiberglass roof, the material itself degrades over time, becoming more susceptible to cracks & damage.
• Seams & Edges: The seams where the roof material meets the front, back, & side caps are notorious weak spots.

2. Windows & Doors: The Sneaky Intruders

• Weep Hole Clogs: Those little slots at the bottom of your window frames are called weep holes. They're designed to let water drain out. When they get clogged with dirt & debris, water backs up & spills inside.
• Failing Seals: The rubber gaskets & sealant around the window frame can dry out, shrink, & crack, creating a path for water. This is especially true in harsh climates.
• Improper Installation: Sometimes, a window isn't sealed correctly from the factory, or the clamp ring that holds it in place is the wrong thickness, preventing a tight seal.

3. Slide-Outs: A Moving Target

• Worn Gaskets & Seals: The rubber "wiper" seals on the outside & the bulb seals on the inside are constantly working. They can tear, get stiff, or get knocked out of alignment, allowing water to get past.
• Slide-Out Roof & Seams: The roof of your slide-out is just as vulnerable as your main roof. Pooled water from a sagging slide topper can overwhelm seals.
• Misalignment: If your slide-out isn't retracting evenly or is slightly out of alignment, it can create gaps in the seals that water will happily exploit.

4. The Plumbing System: Internal Threats

• Loose Fittings: The vibrations from travel are GREAT at loosening PEX pipe fittings, especially under sinks & behind the toilet.
• Cracked Pipes: Freezing temperatures are the biggest enemy of RV plumbing. If you don't winterize properly, water can freeze & crack pipes or fittings.
• Faulty Water Pump or Water Heater: The water pump can develop cracks in its housing, & the connections to the water heater can loosen or fail over time.

Playing Detective: How to Find the Source of the Leak

Step 1: The Visual Inspection (Your Most Powerful Tool)

• Inside First: Start inside the RV. Look for the obvious signs: water stains on the ceiling or walls, discoloration, or active drips. But also look for the subtle clues:
  • Bubbling or wrinkling wallpaper: This means moisture is trapped behind the wall panels.
  • Soft spots: Gently press on the ceiling, walls, & floor, especially around windows, slides, & in corners. Any sponginess or give is a HUGE red flag for rotted wood.
  • Musty odors: If you open a cabinet & it smells like a damp basement, you have a moisture problem.
• Outside Second: Get on the roof (carefully!). Look at EVERY inch of sealant.
  • Examine the lap sealant around every vent, skylight, antenna, & seam. Look for cracks, gaps, or areas where it’s pulling away.
  • Inspect the roof membrane itself for any punctures, tears, or cracking.
  • Check all your window & door seals. Are they pliable or are they cracked & brittle?
  • Check your slide-out seals for any visible damage or tears.

Step 2: The Water Hose Test (Simulating Rain)

1. Start at the bottom & work your way up. Begin by spraying the lower part of a window or a slide-out. Have your spotter inside watch for any water intrusion.
2. Work in small, methodical sections. Isolate one area at a time—one side of a window, then the top, then the other side. Wait a few minutes in each spot.
3. When testing the roof, focus on one sealed item at a time (one vent, then the A/C, etc.).
4. If a leak appears inside, you've found your general area. Now you can zero in on the exact point.

Step 3: The Pressure Test (The Professional Method You Can DIY)

• A powerful fan that can be sealed in an opening, like a carpet dryer fan or even a strong box fan.
• Cardboard & lots of duct tape.
• A spray bottle with a solution of soapy water (a good squirt of dish soap in water is perfect).

1. Seal the RV: Close all windows, doors, & roof vents tightly. You want to make the RV as airtight as possible. You might need to temporarily tape over drain pipes & the range hood vent.
2. Set up the fan: Pick a window or vent to mount your fan. Use cardboard & duct tape to create a seal around the fan, so it's blowing air into the RV.
3. Pressurize: Turn the fan on. It doesn’t take much pressure. You should be able to feel the air trying to escape if you hold your hand near a seal. The goal is to create positive pressure inside.
4. Go Bubble Hunting: With the fan running, go outside with your soapy water sprayer. Liberally spray every seam, seal, window frame, clearance light—EVERYTHING.
5. Watch for Bubbles: Wherever you see bubbles forming, that’s a leak! Air is getting out, which means water can get in. Mark these spots with a piece of tape or a grease pencil.

The Fix-It-Yourself Guide: Repairing Common RV Leaks

Fixing Roof Leaks

• Self-leveling lap sealant (for flat areas)
• Plastic putty knife or scraper
• Denatured alcohol or mineral spirits
• Rags
• Caulk gun
• Eternabond tape (for tears & bigger repairs)

1. Clean, Clean, Clean: The new sealant will not stick to dirty, old, or flaky sealant. Use your plastic scraper to gently remove any loose, cracked sealant. You don't have to remove all of it, just the bad parts. Then, clean the area thoroughly with denatured alcohol to remove any residue. The surface must be BONE DRY.
2. Apply New Sealant: For resealing around vents & seams, use the self-leveling lap sealant. Cut the tip of the tube to get a nice, thick bead (about 1/4" to 3/8"). Apply a generous bead directly over the old sealant & the seam. The sealant will flow & level itself out, creating a wide, waterproof seal. Don't be shy with it!
3. For Tears or Punctures: For a cut or tear in the roof membrane, Eternabond tape is a fantastic, permanent solution. Clean the area aggressively with alcohol. Cut a piece of tape with rounded corners (this prevents peeling) that overlaps the damage by at least 2 inches on all sides. Peel back a small part of the backing, stick it down, & then slowly peel the rest off while pressing the tape firmly into place. Use a small roller to activate the adhesive & get rid of any air bubbles.

Fixing Window & Door Leaks

• Butyl tape
• Non-sag Pro-Flex RV sealant or similar
• Plastic scraper
• Denatured alcohol
• Screwdriver

1. Clear the Weep Holes: First, try the easy fix. Use a pipe cleaner or a small wire to clean out the weep holes at the bottom of the window frame. This might be all you need to do.
2. Total Reseal (The Right Way): If the sealant is clearly the problem, the best fix is to remove the window, scrape off all the old sealant & butyl tape, apply new butyl tape to the back of the window flange, reinstall the window, & then run a bead of Pro-Flex sealant around the top & sides of the window frame. Leave the bottom unsealed so the weep holes can drain.
3. The "Good Enough" Fix: If you're not up for removing the whole window, you can scrape out the old, visible sealant & apply a new bead of non-sag sealant. It's not as good as a full reseal, but it can stop a leak in a pinch.

Fixing Slide-Out Leaks

1. Clean & Condition Seals: Regularly clean your slide-out seals with soap & water, then treat them with a rubber seal conditioner. This keeps them soft & pliable.
2. Inspect for Damage: Carefully inspect the wiper & bulb seals for any tears or sections that have pulled out of their track. Damaged seals need to be replaced.
3. Check for Pooling: If your slide topper is sagging & collecting water, you may need to adjust the tension or replace it. Pooling water will always find a way in.

Fixing Plumbing Leaks

• PEX pipe cutter
• PEX crimping tool & crimp rings (or SharkBite style push-to-connect fittings)
• Replacement PEX tubing & fittings
• Rags & a bucket

1. Turn Off the Water! Turn off your city water connection & your water pump. Open a faucet to relieve pressure in the system.
2. Tighten First: For leaky fittings, the first step is always to try & gently tighten them. Often, this is all it takes.
3. Repairing a Crack: If a pipe is cracked, use the PEX cutter to make a clean cut on either side of the damaged section. Use a PEX coupling & crimp rings (or a push-on fitting) to splice in a new piece of pipe. Make sure your cuts are straight & the pipe is fully seated in the fitting.
4. Test Your Work: Once the repair is made, turn the water back on slowly & check for any drips.

The Silent Destroyer: Recognizing Hidden Water Damage

• Feel the Walls & Floor: Routinely press on the walls around windows & slides. Any softness or sponginess is a bad sign.
• Use Your Nose: A persistent musty smell means mold, & mold means moisture.
• Look for Delamination: Bubbles or waves on the exterior fiberglass walls are a sign of delamination, where the fiberglass has separated from the wood substrate underneath due to water.
• Get a Moisture Meter: For under $50, you can buy a moisture meter. This little tool has two prongs you can press into a surface to get a digital readout of the moisture content. It can detect hidden moisture long before you see or feel it. It’s a game-changer.

Prevention is the Best Medicine: Your RV Maintenance Checklist

• Inspect Your Roof Sealant (Twice a Year): This is non-negotiable. Get up there in the spring & fall & touch up ANY crack or gap you see, no matter how small.
• Wash Your RV: Keeping your rig clean does more than just make it look nice. It removes dirt & grime that can hide developing problems & degrade seals.
• Clean & Condition All Rubber Seals: That means windows, doors, & especially your slide-outs.
• Protect Your RV from the Elements: Constant exposure is what kills an RV. When you’re not using it, storing it under cover is one of the best things you can do. If you don't have space at home, finding a covered spot can be tough. That’s where services like Prked come in. You can rent a covered driveway or even a large garage from a homeowner nearby, protecting your investment from sun & rain. It's a pretty cool way to find affordable, secure storage.