Description
Genuine Dometic Water Valve & Vacuum Breaker Assembly for Moderno 8500 Series Toilets
Restore reliable water fill and backflow protection to your Dometic MasterFlush Moderno (8500 series) toilet with this genuine OEM 24VDC water valve and vacuum breaker assembly. A worn or failing water valve is a common cause of a toilet that won't add water, runs continuously, or won't complete its flush cycle — while the integrated vacuum breaker acts as a critical anti-siphon check valve, preventing backflow of contaminated water into your fresh water supply. This kit includes the water valve, vacuum breaker, and the required 1/2" sealing grommet, so you can restore full flush function on your boat or motorhome with everything you need in one box.
Compatible With:
- Dometic MasterFlush 8540 (Moderno, 24V systems)
- Dometic MasterFlush 8541 (Moderno with bidet, 24V systems)
Important — voltage-specific part: This kit is for 24VDC systems only. If your toilet is a 12V system, you'll need part #385312135 instead. Check your toilet's data sticker or existing wiring for voltage confirmation before ordering.
What's Included:
- Water valve / vacuum breaker assembly
- 1/2" sealing grommet
Key Features:
- Genuine Dometic OEM replacement part
- Integrated anti-siphon vacuum breaker protects your fresh water supply
- Includes sealing grommet — no separate purchase needed
- Direct fit for Moderno 8500 series toilets
- 24V configuration — common on larger vessels and commercial coaches
How to Find Your Model Number
Before ordering, check the data sticker on the base or rear of your toilet — it will list a model number such as 8540 or 8541, along with the voltage (12V or 24V). This kit is specific to 24V systems and the Moderno (8500 series) toilet — it is not the same water valve used on the standard MasterFlush 8600/8700/8900 lines. If you're unsure of your voltage or model, contact us with a photo of your toilet's data sticker and we'll help confirm fitment.
Frequently Asked Questions
How do I know if my toilet is 12V or 24V?
Check the data sticker on your toilet's base — voltage is listed alongside the model number. 24V systems are more common on larger vessels, commercial coaches, and some motorcoaches, while 12V is standard on most RVs and smaller boats.
What does the vacuum breaker actually do?
The vacuum breaker is an anti-siphon check valve that prevents dirty or waste water from being drawn backward into your fresh water supply line if water pressure drops elsewhere in the system — it's a critical safety component, not just a water-flow part.
Is the sealing grommet included, or do I need to buy it separately?
It's included in this kit — no separate purchase needed.
Will this fit my MasterFlush 8600, 8700, or 8900 series toilet?
No — this specific valve/vacuum breaker assembly is designed for the Moderno (8500 series) only. Other MasterFlush series use a different water valve assembly.
I ordered the 12V version by mistake — will it work on my 24V system?
No — these kits are voltage-specific and not interchangeable. Installing the wrong voltage part can cause the water valve to fail or not operate correctly. Please confirm your voltage before installation, or contact us to exchange for the correct part.
My toilet won't add water — is this definitely the part I need?
A failing water valve is one of the most common causes of "won't add water" symptoms, but a tripped tank-full shutoff or a failed control panel can cause similar symptoms. If your toilet shows no power or a full-tank indicator light, check that first before replacing this part.
You May Also Need
- 12VDC Vacuum Breaker/Water Valve Kit (part #385312135) — if your system is 12V
- Dometic Moderno Water Supply Hose (part #385311547)
- Dometic Moderno Control Module (12/24VDC)
Special Order – Estimated 7–14 Business Day Lead Time
Please note: This is a special order item.
- Estimated lead time: 7–14 business days
- Lead times may vary based on Dometic manufacturing and availability
- Special order items are non-cancelable and non-returnable once the order has been placed with the manufacturer, except in the case of a warranty issue or shipping damage
- Orders containing both in-stock and special-order items may ship separately or be held until all items are available
