Why Do It

downspout.jpgRoof gutters can deliver a high volume of rainwater to downspouts. Downspouts are often directly piped to streams, and during storms the force and volume of water can contribute to erosion and flooding. South Portland has made great strides in eliminating Combined Sewer Overflow (CSO) areas, but for the time being there are a few that remain. In these CSO areas, downspouts are piped into combined storm and sewer pipes which are designed to overflow into Casco Bay during heavy rains.

In both of the above cases, disconnecting your gutter from its downspout is a way to protect your neighborhood's environment, provided you have a suitable location for diverting rainwater.

In South Portland, downspout disconnection is recommended as a voluntary retrofit, and as part of a Drainage Plan permit application.

See other Drainage Plan options here.

Basic Features

Downspout disconnection involves cutting your gutter pipe just above the downspout pipe, and redirecting the water to a suitable natural or landscaped location.

Site Suitability

With some planning and consideration of location, downspout disconnections are generally suitable for any site with currently connected downspouts. A key requirement is a suitable location for rain from your roof to infiltrate into the ground. If you do not already have such an area, you consider creating a rain garden, conducting soil quality restoration, or installing a dry well. For information on dry wells, see Maine DEP Stormwater Manual, Volume 3, Chapter 6, Section 6.2.1.

Design and Installation

Disconnecting a downspout requires common tools and no special experience. You may need a splash block, downspout elbow, or a downspout extension to redirect water safely to your infiltration area.

Download detailed design specifications for Downspout Disconnection.


Basic gutter, downspout, and landscaping maintenance are required to keep the gutters clear of debris, ensure no erosion is occurring, and that rainwater is being effectively infiltrated into the landscape.