The Department of Buildings

Disconnect Your Downspout

Disconnecting a downspout

The City of Chicago was the first major metropolitan area in the country to successfully implement an inlet control system to relieve basement flooding. The system works by installing restricters to slow the flow of stormwater into the sewer system. Stormwater is detained on city streets for brief periods before flowing back into the sewer system. This measure helps relieve the burden on the sewer system and reduce the frequency of basement flooding and combined sewer overflows into our waterways.

The effectiveness of the inlet control system depends on the number of roof downspouts that are disconnect-ed from the sewer system. While impractical in some places (where there are only hard surfaces or where drainage could impact neighboring property), the potential to reduce basement flooding and increase natural infiltration is great.

The City actively encourages homeowners to disconnect their downspouts from the sewer system and direct the water instead to their yards or gardens. Public service announcements, community meetings, instructional video tapes, brochures and discounts on materials for downspout disconnection have all been provided to homeowners. The City will continue and expand its efforts to educate citizens on the benefits of disconnecting existing downspouts and on alternative uses of stormwater.

Guide to Downspout Disconnection

Downspout disconnection can help prevent basement sewage backup. Before you disconnect your downspout, consider where you are directing the water, and that cold weather will cause icing conditions. When you are completed, your project should be a permanent solution which is beneficial to your grass, flowers, shrubbery and trees.

The following illustrations will demonstrate that the physical disconnection is relatively simple, inexpensive, does not require a permit, and can be accomplished with a minimum of inconvenience. 

Important Things to Remember:  

  1. Direct Downspout extensions towards the street or alley to prevent seepage into building foundations or adjacent properties. 
  2. Firmly anchored splashblocks should be installed if downspout drainage is to travel over landscaping or dirt.  
  3. Do not allow water to splash or pond on adjacent private property. 
  4. Make sure downspout extensions end at least three feet away from basement foundations, and water is being directed on ground that slopes away (downward) from your building.