Avoiding Burns
Set your water heater temperature to 120 degrees F (or the low setting). This setting is hot enough to discourage any bacteria yet will help avoid scalding members of your household. Most people shower with 103-degree F water, so a maximum setting of 120 degrees F isn't likely to reduce comfort. Washington State law requires that all new water heaters be preset to 120 degrees F.
For addition information, contact the National Electric Safety Foundation