Why should you disconnect your downspouts from the storm drainage system?
Runoff from roofs, streets and driveways carries a wide variety of pollutants that is affecting our natural resources. State and local governments are now mandating stormwater treatment for new development - but what about our older homes?
In many cases, their impact is greater because the stormwater runoff is discharged (with little or no treatment) into the nearest creek, lake, wetland and eventually Puget Sound. By disconnecting your downspout, you take responsibility for your roof runoff, and create conditions within your landscape to properly absorb and filter the water.
Don’t disconnect if:
•you are within 500 ft. of steep slopes or landslide-prone areas.
•you have high groundwater or poor drainage in winter (puddles, springs, soggy lawns).
•runoff may flood neighboring properties or sidewalks (for example, high-density housing or condominiums).
•the ground around your house slopes back toward the foundation.
Things to consider before disconnecting:
Does the water have a place to go?
Plan for runoff to be directed to a rain garden, cistern or large landscape area with good drainage.
Can it get there?
Provide a swale, splash block or pipe to direct water away from the house.
Is there a backup exit, in case of a big storm?
Ensure that excess water can overflow to an approved discharge location, like a catch basin in the street.
Disconnecting downspouts can help protect our streams, but they need to be disconnected properly to avoid wet basements, flooding, erosion or damage to neighboring properties.
Tools and materials needed:
•drill or screwdriver
•sheet metal screws
•pipe or flexible downspout extension
•splash blocks and/or rocks
How to disconnect your downspout:
1. Cut the downspout pipe.
Measure about 9” from the top of the standpipe (which goes into the ground). Remove this section of downspout with the hacksaw. You may adjust the height to fit the new elbow.
2. Plug the sewer standpipe.
Measure the storm sewer standpipe diameter and install an expansion cap to plug it.
3. Install the new elbow and pipe to convey water away from the house.
Use similar downspout material or use plastic flexible downspout extension pipes which can also be found at hardware stores. If needed, crimp the downspout pipe with needle-nosed pliers so that it fits into the new elbow or extension pipe. Drill a hole on either side of the fittings, and install sheet-metal screws to attach. If the downspout needs further support, attach it to the house with a hanger bracket.
4. Slow and spread the stormwater.
Use a splash block, rock pad or perforated pipe at the end of the extended downspout to convey the water to landscape areas, a rain garden or rock-filled infiltration trench.
If you have any questions, consult the expertise of a professional, or contact the Community Conservation Team at the Snohomish Conservation District at 425-335-5634 or firstname.lastname@example.org.
Minimum Distances to Discharge
(more is better):
•5 ft. away from your home, if you have a crawlspace
•10 ft. away from your home, if you have a basement
•5 ft. away from a property line
•10 ft. from neighboring buildings
By disconnecting your downspout, you take responsibility for your roof runoff, and create conditions within your landscape to properly absorb and filter the water.
Better Ground is brought to you by the Snohomish Conservation District.
528 91st Ave NE Lake Stevens, WA | 425-335-5634 | www.betterground.or