What is a combined sewer overflow?

A combined sewer overflow (CSO) refers to a discharge of partially treated or untreated waste water prior to treatment. CSO's generally occur in response to wet-weather events.

Combined sewer overflows occur far less frequently than they did in the past. For information regarding improvements Milwaukee Metropolitan Sewerage District (MMSD) has made to the regional collection system in an attempt to reduce overflows, please access their resource.

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1. What is a combined sewer?
2. Where is Shorewood's combined sewer system?
3. How does a combined system deal with stormwater?
4. What is a combined sewer overflow?
5. Why disconnect downspouts?