Question

When did they install bathrooms on airplanes

Answer 1

donno dude
:P

Answer 2

At the time of the first passenger planes they had a bucket at the back of the plane. At the end of the 1930s they put in the first bathroom that was apart from the rest of the plane. They had a bowl that was removable and the crew would dump it after the flight. :P In 1945 there was the first fixed toilet bowl with poo poo going into a tank, and then in 1958 the first modern-ish airplane toilette was installed.

Answer 3

somewhere around 1930, when long distance flying began.

Before that there were no proper toilets but sort of "bucket" toilets, not as hygienic and smell free as today.

Before that it is speculated people used bottles to relieve themselves in flight..

Answer 4

which do you want, simple buckets, or the modern lavatories of today?