A burst tank, water spreading across the garage, or a gas smell near the heater is an emergency — shut off the cold supply valve on top of the unit and the gas control or breaker, then call. The companies flagged 24/7 in this guide publish round-the-clock availability; same-day responders cover most other failures.
Turn the cold water supply valve on top of the heater clockwise to stop the flow. On a gas unit, turn the gas control knob to off; on electric, flip the breaker. Move anything water can ruin off the floor. Those three steps end the damage — everything after is repair, not crisis.
A tank leaking from the body, active flooding, no gas shutoff you can reach, scalding-hot output, or any combustion smell — call immediately, day or night. A unit that simply stopped making hot water overnight is urgent but survivable until morning, and same-day service usually costs less than a 2 a.m. dispatch.
Plenty of companies advertise 24/7; fewer staff overnight technicians rather than an answering service that books you for morning. Our directory records who publishes a 24/7 commitment — recorded as the company's claim — and our profiles note what we could verify. Asking "is a technician dispatched tonight, or am I booked for tomorrow?" sorts the two in one question.
Browse every water heater company in the guide or see how we rank the top picks.
The companies marked 24/7 in our comparison table and directory publish round-the-clock availability — recorded from their own service commitments. Expect an after-hours dispatch premium. For non-flooding failures, booking the first morning slot with a same-day company is usually cheaper and nearly as fast.
It depends where the water comes from. A drip at a fitting or valve is urgent but contained once you shut the supply. Water from the tank body means the steel has failed; shut off water and fuel now, because that one floods. Either way, shutting the cold supply valve stops the immediate damage.
After-hours dispatch fees vary by company and are rarely published, which is why fee transparency is one of our ranking factors. Ask for the dispatch fee and whether it credits toward repair before confirming the visit. A burst tank usually ends in same-visit replacement, so ask what units are on the truck.