Redirect Downspouts

Rain, roofs and runoff

Did you know that each downspout on a house can drain approximately 12 gallons of water per minute during a one-inch rainfall?

 Fortunately, there are many things that property owners can do to put rainwater to good use while reducing the amount of stormwater runoff that ends up in local waterways.

If managed properly, the water that flows off rooftops can help keep lawns and gardens green while lowering water bills during spring and summer months. However, most downspouts direct rainwater down driveways and sidewalks to underground pipes that lead to storm drains or sanitary sewer lines. What’s more, these paved surfaces increase the speed and amount of water that rushes into streams, causing stream bank erosion and harming wildlife habitats.

This “stormwater runoff” picks up pollutants from motor oil, lawn chemicals and pet waste along the way, before entering lakes and streams — untreated. The large amount of untreated water entering the storm sewer system — and eventually our streams and lakes — has lasting health, safety, environmental and economic impacts on communities.

Combined sewer overflows

Combined sewers are older systems that carry both stormwater and wastewater to treatment plants. When rainstorms fill combined sewers beyond capacity, the result is a Combined Sewer Overflow — a discharge of untreated wastewater and stormwater into local waterways. Combined sewers are costly to replace and are still in use in older areas of the region.

Why disconnect your downspout?

Downspouts that connect directly to sewer pipes increase the risk of sewer overflow and flooding. Disconnecting your downspout from a sewer intake pipe (standpipe), then redirecting the flow of water to a grassy area or garden is a simple process that makes a big difference to the environment.


  • Hacksaw
  • Cordless drill
  • Tape measure
  • Pliers
  • Sheet metal screws
  • Downspout elbow
  • Downspout extension
  • Standpipe cap

There are different types, lengths and sizes, of standpipe caps, so be sure to take measurements before shopping. Capping the standpipe prevents water from going in while keeping pests (such as rodents) from entering/exiting the pipe.


  1. Cut the existing downspout approximately 9 inches above the sewer standpipe with a hacksaw.
  2. Cap the sewer standpipe.
  3. Attach elbow by crimping the downspout with pliers to ensure a good fit. Connect elbow to downspout using sheet metal screws. It may be necessary to pre-drill holes.
  4. Attach the elbow INTO the extension and secure with sheet metal screws. Water should drain at least five feet away from the house, so direct the extension accordingly. A splash block may help direct water further away from the house.