Commercial connections

Commercial or multi-unit building sewer connections and roof drain information.

Roof drains

One common situation for commercial or multi-unit buildings still connected to the sanitary sewer system is to have a roof drain that runs down through the building and into the sanitary sewage lines.

Commercial/Industrial/Multi-unit flat roofed buildings with rain leaders connected to the Sanitary Sewer diagram

The two disconnect routes

There are two routes for disconnection in this case.

1. Redirect the rainwater

One is to redirect the rainwater onto grade. This method is appropriate if there is sufficient drainage at grade to handle the flow during rainfall.

Roof drain disconnected and redirected onto grade diagram

2. Install plumbing to direct rainwater

The second route is to install plumbing that directs rainwater to a storm drain underneath the street.

Roof drain redirected into storm drain underneath the street diagram

Request accessible format

If you need help with this information, please email 311, or call 311 or 612-673-3000.

Please tell us what format you need. It will help us if you say what assistive technology you use.

Contact us

Surface Water & Sewers

Public Works




Public Service Center
250 South 4th St, Room 300
Minneapolis, MN 55415

Office hours

Monday – Friday
7 a.m. – 3:30 p.m.