DIY: How to Disconnect Your Downspout to Protect Rivers

Published on June 2nd, 2009 | by

Where do the downspouts off of your house’s gutters flow?  Do they enter into the city’s sewer system?  For many cities, this is a problem.  The city of Portland, Oregon explains:

A large part of Portland has a combined sewer system that carries sewage and stormwater runoff in the same pipes. When it rains, the combined sewers fill to capacity and some of the stormwater and sewage mixture overflows to the Willamette River.

Downspouts on many homes are connected directly the combined sewer system and roof runoff from those homes contributes to combined sewer overflows (CSOs). Disconnecting those downspouts reduces the amount of water entering the system and reduces CSOs.

Image by francis storrPortland promotes downspout disconnection
Portland promotes downspout disconnection

Disconnecting your home’s downspouts allows roof water to be used for lawn irrigation and filter pollutants, similar to planting a rain garden.  Just one disconnected downspout can redirect thousands of water a year.  Over 58,000 homes have disconnected their downspouts in Portland.

Portland has a Downspout Disconnection Program in which incentives are available for DIYers or the city will do the work for free!  According to the city, the following steps should be followed to safely disconnect your downspouts:

1.  Observe your property:

  • Where do your current downspouts flow to?  If they are not connected to the city sewer system, then they may not need to be disconnected.
  • What is the slope of your property? Downspouts should not be disconnected if the slope of your property is over 10%.
  • How much area is available for drainage?  Disconnected downspouts should discharge water at least six feet from the home’s basement or two feet from a slab foundation.  You need at least 10% of the roof area in your yard size to safely absorb the stormwater.
  • Where are your property lines?  Your disconnected downspout extension must be at least five feet from your neighbor’s property and three feet from any public sidewalks.
  • What kind of access may be affected by the relocation of the water?  Obviously, you wouldn’t want your relocated roof water flowing over your driveway, patio, walkway, etc.
  • Do other hazards exist?  You need to consider the location of retaining walls, septic systems, etc. in relocating your roof water.

2. Design your disconnection:

  • You will need the following tools:  a hacksaw, a drill, pliers or crimpers, a tape measure, and a screwdriver.
  • Based upon your design, you will need a variety of elbows and extensions to match your gutters. Be sure to use durable, gutter-grade materials.
  • Mark the downspouts to be disconnected and lay out the path for the extensions, including obstacles you may need to circumvent.

3.  Disconnect!

  • Cut the downspout with a hacksaw about nine inches above where it enters the sewer system.
  • Plug the standpipe where it enters the sewer system at the cut.
  • Attach an elbow OVER the downspout to prevent leaking. You many need to crimp the downspout with needle nose pliers to make it fit inside the elbow.
  • Measure, cut, and attach extensions OVER the elbow.
  • Secure the elbows and extensions with sheet metal screws.
  • An optional splash block at the end of the extension can be used to prevent erosion.

4.  Maintain your gutters and disconnected downspouts:

  • Clean gutters at least twice a year; monitor downspouts and extensions for clogging.
  • Caulk holes.
  • Ensure gutters drain into downspouts.

Portland offers discounts on city utility bills if you disconnect your downspouts.  For more information and technical assistance on disconnecting downspouts, including detailed how to brochures,  visit CleanRiverRewards, Downspout Disconnection Program, and Rainwater Harvesting for Drylands and Beyond.  This low maintenance project offers a great solution for reusing stormwater and preventing it from burdening city sewer systems.


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