How to Repair a RV Holding Tank

by Lynda Altman
RV tanks can be damaged when driven over rough terrain

RV tanks can be damaged when driven over rough terrain

RV holding tanks are durable. Sometimes leaks occur due to rough terrain, road debris or freezing. Translucent polyethylene and black ABS plastic are the most common materials used for holding tanks. Before starting any repairs to a holding tank, drill a hole in each end of the crack to prevent it from becoming larger. Drain the holding tank. Perform the repair in a well-ventilated area.

Repairing Translucent Polyethylene Holding Tanks

  1. Clean the damaged area completely using acetone or rubbing alcohol.

  2. Use sandpaper to rough-up the surface of the tank.

  3. Cut a piece of fiberglass cloth that is slightly larger than the damaged area.

  4. Put on gloves. Using the Syon Seal-N-Place kit, break off the tip of the metal tube contained in the resin bag. Keep the bag sealed.

  5. Turn the key at the end of the metal tube to empty the contents into the resin bag. Knead the bag until the resin and contents from the tube are completely mixed. It takes a few seconds to do this.

  6. Brush a layer of resin mixture over the damaged area. Lay the fiberglass cloth over the resin layer.

  7. Cover the fiberglass cloth with a layer of resin. Keep the fiberglass cloth smooth and flare-out the edges with a brush to create a smooth finish.

Repairing Black ABS Holding Tanks

  1. Clean completely the area around the crack or break. Use acetone or rubbing alcohol to rid the area of road grime.

  2. Cut a piece of fiberglass cloth slightly larger than the area requiring repair.

  3. Put on gloves. Saturate the fiberglass cloth with the cyanoacrylate adhesive. Place the cloth over the damaged area. Smooth out the fiberglass cloth so there are no ridges or bumps. Use a gloved hand for this.

  4. Using a brush, cover the fiberglass cloth with the accelerator that came with the cyanoacrylate adhesive. The accelerator reacts with the adhesive to harden it within a few minutes. Once hardened, the repair is complete.

Items you will need

  • Disposable gloves
  • Cordless drill
  • Tank draining kit
  • Scissors
  • Acetone or rubbing alcohol
  • Shop rags
  • Cyanoacrylate adhesive
  • Fiberglass cloth
  • Sandpaper
  • Syon Seal-N-Place
  • Small paintbrush


  • Syon Seal-N-Place hardens completely within six minutes. Work quickly.
  • Cyanoacrylate adhesive is available at most hobby shops.
  • It is possible to weld polyethylene plastic tanks with specialized equipment. A qualified RV center can weld the tank.


  • Large cracks (longer than a dollar bill) or holes cannot be repaired, and the tank must be replaced.
  • Cracks in the tank must be drilled before emptying the tank to prevent further damage. It is messy: Wear old clothes.


  • "Trailer Life's RV Repair & Maintenance Manual," 4th Edition, by Bob Livingston, 2002.

About the Author

Lynda Altman started writing professionally in 2001, specializing in genealogy, home-schooling, gardening, animals and crafts. Her work has appeared in "Family Chronicle Magazine" and "Chihuahua Magazine." Altman holds a B.A. in marketing from Mercy College, a black belt in taekwondo, master gardener certification, a certificate in graphic arts and a certificate in genealogy.

Photo Credits