Driving around San Francisco, you may pass a house with its garage door open and be surprised by a toilet right in the middle of the garage. What gives?
One theory is that they are examples of "Pittsburgh toilet," which originated in the Pennsylvania city in the early 20th century. (Video above.) Back then, steelworkers and miners would use these loner loos and the accompanying wash basin to relieve themselves and wash off the day's grime before entering the home. But that may not be the case in San Francisco.
From SFGate:
San Francisco real estate agent Ciara Piron has a different theory for these toilets, at least for the ones prevalent in the Sunset District. She's seen plenty of these solitary toilets while selling homes in the area and took it upon herself to do some research. She found that on just one block, 26 homes were built in 1928. That's speedy construction, and she posits that the workers erecting these homes would need another place to "go" while the houses were being completed — portable toilets had yet to be invented.
Rather than get rid of the extra toilets when construction was complete, workers left it up to the new homeowner to decide its fate[…]
Another popular theory for these toilets' existence in San Francisco ties them back to a plumbing safeguard of sorts. If there's a sewage backup in the system in the home, it would likely erupt in that lower-level system, where less damage is likely to occur and clean-up is easier.
