Check the hot water unit’s age, model, energy source, temperature, pressure, leaks, unusual noises and signs of rust or damage. Confirm whether all taps are affected, whether the issue is constant or intermittent, and whether the circuit breaker or gas supply has tripped or been interrupted. Do not remove covers, adjust gas components or attempt electrical repairs yourself. Take photos of the unit and contact a licensed plumber or, for electrical faults, a licensed electrician for advice and repairs.