Sewage
From SimCity Wiki
All sims produce wastewater called sewage.
If sewage is not properly disposed of, it turns into ground pollution.
Sewage output pipe can be constructed to transport the sewage to a remote part of the city.
Sewage Disposal Structures
Sewage Maps
Sewage - shows sewage levels and where sewage is flowing to.
Ground pollution - shows the location and severity of ground pollution and the building producing it.