If you start smelling foul odors coming from your RV's waste holding tank, it may have cracked. Waste holding tanks in modern RVs are typically made from acrylonitrile butadiene styrene (ABS), which is a very strong form of plastic. Despite its strength, ABS can still crack and cause your waste tank to leak. This often happens when you go over a bumpy road and the waste tank is nearly full since the weight of the contents sloshing around inside the tank can create enough pressure to crack it. Thankfully, ABS is very easy to repair. To learn how to patch a crack in your RV's ABS holding tank, read on. 

Clean the Holding Tank and Let It Dry

The ABS cement you'll need to patch the crack in your holding tank won't adhere to the tank if it's wet. The first step to repairing the crack is to completely drain the tank, wash it out with water, and then let it fully air dry. Opening the lid of the tank will make it dry faster.

Wear a Respirator

Patching cracks in any plastic, including ABS, requires using solvents that are hazardous if you inhale them. You'll need to wear a respirator that's been rated to block organic compounds when you're patching your holding tank. You can buy one at a home improvement store.

Drill Holes Near the Crack

Drill two tiny holes at both ends of the crack. The holes will prevent the crack from spreading underneath the cement you'll use to patch it, which is a common cause of patches failing.

Sand the Damaged Area and Apply Acetone to It 

Use steel wool or a wire brush to lightly scrape the area around the crack. This will help the ABS cement adhere better to your holding tank. After sanding the area lightly, wet an old washcloth with acetone and rub the portions you've sanded. This will slightly dissolve the plastic, which also helps the ABS cement adhere to the tank. The washcloth will be covered in plastic once you're done, so you'll have to throw it away.

Patch the Prepared Area Using ABS Cement

Finally, you're ready to patch the crack using ABS cement. Apply a thin layer of ABS cement to the area you've prepared using an old paintbrush, and then wait for it to dry. Repeat this process using several thin layers of ABS cement, allowing them to dry completely between each new layer. You'll slowly build up a thick layer of ABS cement on your holding tank that will patch the crack and prevent your holding tank from leaking.

Once your final layer of ABS cement is completely dry, you're ready to start using your holding tank again. If you don't feel comfortable working with hazardous chemicals or if you want to ensure the repair is perfect, you should take your RV to an RV repair shop to have the crack in your holding tank patched. RV repair professionals will be able to provide you with a long-lasting repair that will stop your holding tank from leaking.

Contact a local RV repair service to learn more.