Boston and surrounding areas have been working on that for years, with good results. Here's some info if you're interested: http://www.mwra.state.ma.us/03sewer/

Boston and surrounding areas have been working on that for years, with good results. Here's some info if you're interested: http://www.mwra.state.ma.us/03sewer/html/sewcso.htm#16southdorchesterbay http://www.mwra.state.ma.us/03sewer/html/sewcso.htm#16southd... The specific project I linked to involved installing over 25 miles of storm drain to avoid combined sewer/storm overflows into the ocean. We lived on one of the impacted streets. Older houses had gutter downspouts that dumped all rainwater into the combined storm drain/sewer system. The MWRA came to neighborhood association meetings, and helped residents to re-aim downspouts onto green space.