A combined sewer carries both domestic sewage and stormwater.

For instance, one goal of the plan was separation of combined sewer and storm-drain systems in some cities.

A public combined sewer collects both foul and surface water drainage.

Especially in cities with combined sewers, treatment plants do not function properly after heavy rains.

A major project of this group is the removal of stream discharges from municipal combined sewers.

The only permanent solution is the installation of new larger combined sewers.

The tunnel provides a buffer to allow some combined sewers to remain in service.

Or maybe a combined sewer and drainage-tunnel - there were plenty of those in flood-conscious Derry.

This type of sewer design is no longer used in building new communities, but many older cities continue to operate combined sewers.

Ms. Sankovitch says she now focuses much of her attention on the problem of combined sewers.