We have been needing plumbing and sewer systems even longer than we’ve had them, of course, but what could we do? Wandering hunter-gatherers tend not to think much about the plumbing problem. They just walk on, hunting and gathering as they go, and no problem exists. But when you stay in one place, something has to be done.
In Europe and the US, the need to develop sanitary sewer systems arose as cities became larger and populations more dense, especially as a result of the Industrial Revolution. In the US, it has been standard practice to have good sanitary sewers in our cities since about the middle of the twentieth century, perhaps a little earlier. It seems hard to believe, but it is true, that is has not been all that long since the bathroom was out back in a little shack of its own.
But since then, we’ve learned a lot about sewer systems and plumbing, and now we have all the modern conveniences. And fortunately, we have qualified plumbing contractors to install those conveniences and keep the plumbing in good order.