How are sump pumps typically used?
Sump pumps are installed particularly where basement flooding is seen as a problem, but are also used to ameliorate dampness by lowering the water table under the foundation. They pipe water away from the house to any place where it no longer presents a hazard, such as a municipal storm drain or dry well. Older properties may have their sump pumps connected to the sanitary sewer, but this is frowned upon now (and may be against the plumbing code) because it can overwhelm the municipal sewage treatment system. Though in some cases, a sump pump is used when a lower floor is below the sewer lines, to pump greywater or blackwater waste from that floor to the lines.