Easy leaking toilet fix: Replace the ‘ball seal’ on your RV’s toilet

Welcome to “In the RV Shop with Dustin”. We recently had a customer in the shop with a Dometic 310 toilet that was leaking water from the bowl into the holding tank. After performing a simple operation and visual inspection, we narrowed down the culprit to the “ball seal.” Did you know this replacement is so easy that just about anyone can do it?

Dometic Toilet bowl seal on a 310 model.

Here is a simple, step-by-step installation guide to help you with this repair

Dometic 300/310/320 Flush Ball Seal Installation


  1. Turn off water supply before working on the unit.
  2. Hold flush pedal down to keep flush ball open and to release the water pressure in system.
  3. Grasp inside edge of seal and pull upward to remove from toilet. Remember to use rubber gloves.
  4. Thoroughly clean lower bowl rim area where seal was located; you can even use an old toothbrush.
  5. Release flush pedal to close flush ball. Thoroughly clean surface of flush ball.
  6. Insert new seal in base, making sure seal is firmly pressed outward against lower bowl rim.
  7. Press flush pedal to open flush ball, and spread thin layer of silicone grease or petroleum jelly under the seal where it will contact flush ball. Release flush pedal.
  8. Lightly press down around circumference of seal to insure seal is in proper position.
  9. Turn on water supply.
  10. Add water to bowl and check for leaks.

Here is the Dometic Flush Ball Seal Replacement for 300 310 320 RV toilets. In addition, if you want to extend the life of your toilet bowel seal, I recommend that you use a toilet bowl lubricant and seal conditioner.

More from Dustin

Make sure you check out my website, California RV Specialists, and our YouTube channel for more helpful information, and see our published articles on RVtravel.com and other social media pages.