Every year in this country, thousands are treated for burns from scalding hot water. Children are more prone to be the victims of this, but it could happen to anyone. You have probably at one time or another experienced how your comfortable shower turns painful when someone else in the home turns on a faucet or flushes a toilet.
Your water heater might put out water in the range of 120-160 degrees fahrenheit. At 160 degrees, it will take less than a second for scalding to occur.
If you are running water at one place in your home and there is a sudden loss of water pressure, the water at your location could get dramatically hotter in a short period of time.
One way to prevent this is to install anti-scald valves, either at the fixtures, or at the water heater so as to cover the whole building. The way this works is that the valve mixes the cold water with the outgoing hot water to keep it at a stable temperature. Some of these devices are automatic, and will adjust the mixture depending on how hot the water leaving the tank is, while others can be manually set by the homeowner.