Safety boundary: Do not rely on the control dial alone. Water temperature should be checked at a fixture, and anti-scald protection may be appropriate.
Why settings are complicated
Stored-water temperature, distribution losses, plumbing codes, appliance needs and occupant vulnerability all matter. A single internet number is not a universal answer.
Scald risk
Young children, older adults and people with reduced sensation can be injured quickly by very hot water. Mixing valves and pressure-balanced or thermostatic shower valves can reduce risk.
Legionella considerations
Very low storage temperatures can create microbial concerns in some systems. Follow public-health, code and manufacturer guidance for your installation.
Professional adjustment
Ask a plumber or qualified contractor to evaluate storage temperature, mixing, recirculation and fixture protection as a system.
Useful questions to record
- Is the problem at one fixture or throughout the home?
- Is there active leakage or relief-valve discharge?
- What fuel, capacity and age is the unit?
Related guides
Tank, Tankless and Heat-Pump Water HeatersA Canadian comparison of storage tanks, on-demand systems and heat-pump water heaters.Sizing a Water HeaterHow first-hour delivery, recovery and peak demand matter more than tank volume alone.No Hot Water or Inconsistent TemperatureSafe observations that distinguish whole-house, fixture and capacity problems.Water Heater Leaks and MoistureHow to identify the source area and protect the building without unsafe repairs.