Verified Compatibility

Dometic 385311658

Flush Ball Seal Kit

Dometic 385311658 is the flush ball seal kit for the 310 Gravity-Flush Toilet. The rubber seal the flush ball closes against at the bottom of the bowl. It is what keeps water sitting in the bowl between flushes, and it is the part that fails when the bowl drains dry.

Is it compatible?

Compatible with

  • 310 Gravity-Flush Toilet

Every model above is named in a manufacturer parts list, cited in full further down this page.

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Compatible models, and the document that says so

  • 310 Gravity-Flush Toilet

    Verified against Dometic Parts List, 310 Gravity-Flush Toilet (P/N 600346224, Rev. 01/10).

We have not verified 300, 301, 311, 320, 321. Retailers commonly list this seal as fitting the whole 300/310/320 range. Dometic’s parts list that we hold covers the 310 only. Check your model ID label before ordering.

How to tell which one you have

Dometic puts the model ID label on the toilet base, underneath the water valve. Read the model number off that label rather than guessing from the shape of the toilet.

Is this part still current?

Yes. 385311658 is listed in Dometic Parts List, 310 Gravity-Flush Toilet, P/N 600346224, Rev. 01/10, which is the current parts documentation we hold for this model. Dometic sells this number today: it is listed as Flush Ball Seal Kit (385311658) at $32.73 under spare parts on Dometic’s current US RV toilets page, read 2026-08-30. That page does not name the models it is compatible with, so the compatibility above still comes only from the 310 parts list.

Also worth having before you start

  • Disposable nitrile gloves

    General guidance for any waste-contact job, not specific to one manufacturer: wear protective gloves and eye protection when you touch anything that has been in contact with human waste, and disinfect your tools and work surface afterwards. If you do not already have a box in the camper, get one before you start.

These are supplies, not replacement parts. We have not matched them to your model, because they do not need to fit anything.

Check this before you order

  • Read the model number from the label on the base, under the water valve.
  • Confirm your toilet is a Dometic or SeaLand gravity-flush unit, not a Thetford.
  • If your model is not a 310, check the seal against your own model’s parts list first.

Before you start the job

Dometic notes that mineral deposits from hard water build up on the flush ball and seal and cause a slow leak. Cleaning the ball and seal sometimes fixes the leak without a new part.

Not the part you are holding?

Search by number, or check how to tell two similar-looking parts apart before you order.

Search by part numberWhy similar parts may not fit

Current marketplace inventory

Listings from eBay

We verified the part above from manufacturer documents. The listings below are current eBay inventory, and eBay sellers set their own titles, prices and shipping.

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Camper Replacement Parts is not the seller. Price, shipping, stock and item condition are set by the eBay seller and can change at any time. We may earn a commission if you buy through these links.

Manufacturer
Dometic
OEM part number
385311658
Part
Flush Ball Seal Kit
Compatible models
310 Gravity-Flush Toilet
Status
Listed in the most recent parts documentation we hold
Primary evidence
Dometic Parts List, 310 Gravity-Flush Toilet, P/N 600346224, Rev. 01/10; Dometic Installation and Operation Manual, 300/310/320 Series, Revision D, Form No. 600346504; Dometic RV Toilets, current spare parts and accessories
Last checked
2026-08-24

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Where our information comes from

We work from the manufacturer’s own documents. We have not installed this part ourselves, so everything here comes from the documentation rather than from a workshop.

Last checked 2026-08-24.