this is completely off topic from coffee, but i find this very interesting.
this is a shower head in my hotel room in Quetzaltenango.

mostly, in most of regular homes or hotels, there is no hot water tank/boiler. so basically, all the sink has only one knob for cold water and for shower, this is how it looks like. there is a small device connected to the shower head and you will see couple of electric wires going into this device. so, when you turn on the water for shower, the electricity bottle (i call it that) sends electricity to heat up the water and semi-hot water comes out. it is not hot, just warm. gian phoi thong minh

but if you turn the water all the way up, then, the power of electricity is too weak to heat up the amount of water pouring down, so you got to make it drizzle. 

I wonder whether this type of shower is allowed in USA, whether FSA permits this kind of devise. 

for me, so far so good. I have not electrified yet. That is a good thing.

PS : FSA (Federal Shower Agency). I just made that up.