Thermador Steam & Combi Oven Water Tank Refill Safety Notice

Thermador steam oven water tank notice — owners of Thermador Steam & Combi wall ovens, including Masterpiece Steam and Professional Combi models, are advised on safe water tank refill procedure, approved water types, and burn prevention during refill operations.

Why this matters

Steam & Combi wall ovens use a removable front-mounted water tank that supplies steam to the cooking cavity through an internal heater and atomizer system. Refilling the tank during a hot cycle — or refilling with water containing minerals or contaminants — can cause sudden steam bursts, scale buildup in the steam generator, and reduced steam oven performance over time.

Approved water types

Distilled water: the only Thermador-approved water type for the steam tank
Filtered water: NOT approved — even high-quality filtered water contains dissolved minerals that scale the steam generator
Tap water: NOT approved — causes accelerated scale buildup and shortens steam generator service life dramatically
Bottled spring water: NOT approved — contains dissolved minerals
Reverse osmosis water: generally acceptable as a substitute for distilled if RO is the only water source available, but distilled is preferred

Safe refill procedure

Refill the water tank only when the oven is cool — never during an active steam cycle
Pause any active cycle and allow the cavity to cool to room temperature before opening the water tank compartment
Slide the tank out using the front release latch — the tank should slide smoothly without resistance
Pour distilled water to the maximum fill line — do not overfill
Wipe any spilled water from the exterior of the tank with a clean dry cloth
Reinsert the tank fully into the compartment until the latch clicks into the closed position
Resume the cycle only after the tank is fully seated and the front display confirms tank presence

Burn prevention

Never open the water tank compartment during an active steam cycle — residual steam pressure can release suddenly
Never refill the tank with hot water — use only room-temperature distilled water
Wear an oven mitt when handling the tank if a previous cycle was recent — the tank exterior can be warm
Keep children away from the steam oven during and after steam cycles

Tank cleaning

Empty the tank between long periods of non-use. Wash the tank with a mild soap solution monthly to prevent biofilm buildup. Never run the dishwasher on the steam tank — the high heat can damage the tank seal.

When to call a technician

If the steam oven displays a water tank error after a properly performed refill, or if the steam output is noticeably reduced, schedule a Thermador-certified technician — the tank presence sensor or the steam generator may need service.