Hot water systems in homes are generally set to not go hotter than 120F, because much hotter than that could burn somebody in seconds. 120F is a bit more than

Hot water systems in homes are generally set to not go hotter than 120F, because much hotter than that could burn somebody in seconds. 120F is a bit more than "lukewarm" (which I take to be an exaggeration), but is nevertheless cooler than anybody serves standard coffee at. 140F (60C) water can give you third degree burns in 5 seconds.