If your water heater is set at 160 degrees how long would it take to burn you seriously?

If you were to immerse your hand into 160F water, that would be sufficient to burn you most seriously, generating 2nd degree burns in under a minute -- easily. Given enough immersion time, 3rd degree burns are inevitable. However, that's not how you framed the question. If the water in your water heater is 160 degrees, that doesn't mean that's what's coming out of the tap, and it would be impossible to fill most sinks with 160F water if the water in the heater was 160F. Here's why: First, there's a lot of water in the pipes between the heater and the sink. That water will range from less than 160F near the heater to room temperature at the sink. However, in winter, the water nearest the outside wall may well be far below room temp. Even if you run the cooler water down the drain, the hot water from the heater is passing through colder pipes, and dropping calories all the way. Naturally, the material the pipes are made from, and the amount of insulation plays a part too. Once it hits the sink, it'll shed a huge amount of heat as it averages the temperature of the sink and its own higher temp, in order to reach stasis. In my house, where I run the heater at 140F, I can't get water out of the tap at over about 110F, over about a 30' run. So the answer is (and I don't mean to be too literal -- this is a problem my wife and I discuss a lot -- I like hotter baths :} ), that while 160F water is WAY over what you can safely stand as a human, setting your water heater to 160F doesn't mean that's what your bath temp is going to be.