While water heaters are common in many places ALL over the world, in many countries, just running water that's clean would be an improvement.... As I'm typing this, most reading it are much luckier than they know. In the US, most houses I've been in have big tanks where water is kept hot for whenever it is needed. When I say 'big,' I mean 40 gal or about 141 liters. Our water heater here is actually a pretty small one too. When I was in Japan, most water heaters I saw burned natural gas and heated water as needed.