How come all sewers don’t stink?


Sometimes ones in the city do. But like, why not all sewers? Do the good ones have valves that hold all the poop and pee back?

In: 0

If there’s poo and pee, then it’ll stink.

Water traps can prevent gases from escaping, but sometimes for the smell to really spread you just need a hot day.

Sanitary sewers (toilets, your home, etc.) and storm sewers are independent systems. Well typically. With sanitary systems, yes, there is a valve of sorts. The water in all the drain traps is your “valve.” The whole purpose of drain traps is to literally trap water to prevent sewer gas from coming into your home.

Storm sewers are just for rainwater runoff.

As mentioned already, the toilet but also water sinks have a trap which avoids this. The waste water line needs to have a venting line to the roof which prevents that another trap gets sucked empty by flushing. It may also stink if the water in a trap gets evaporated over long time .

I’ve worked around a few sewers before, one thing that did often stand out was the smells of detergents and soaps. On a cold day in the morning, you’d get the showers and washing water, and it would be pretty warm in them too.
There would be more soaps and shower gel than crap, so they wouldn’t be all that bad.