You may not give a lot of thought to your downspouts, but the water that falls on your roof and through your gutters could be contributing to larger stormwater management problems. Keep reading to learn why stormwater is such a big deal and how disconnecting your downspouts could be an easy first step! In many older neighborhoods, roof runoff goes directly into a combined sewer and stormwater system. During a big storm, rainwater can overwhelm the system causing sewer overflows. Newer neighborhoods and developments might have a dedicated stormwater system, but this water usually flows to local waterways, so reducing the amount of flow during a major rain can help prevent stream erosion.
By disconnecting your downspouts you keep the water on site, but before you pull out your hacksaw, make sure you have a plan for where that rainwater will go. To avoid problems with settling and wet basements, water should always be directed away from the foundation - just make sure you're not directing it towards your neighbor's house either! Roof runoff should also not be dispersed towards sloped areas (to prevent erosion) or parts of your yard that you know tend to be soggy after a good rain.
As always, the best method for keeping water on site will vary depending on where you live, what kind of yard you have and what is recommended by your town or city. It's always a good idea to do a little investigating first to see if there are any local guidelines or regulations.
Steps 1. & 2. - Use a hacksaw to cut the downspout at least 9" above where it goes into the sewer standpipe. Install a plug or cap over the standpipe to block sewer gases.
Step 3. - Install a new elbow and pipe to lead water away from the house. A minimum distance of 10' should be used if you have a basement, 5' if you don't.
Step 4. - Add a splashblock (inexpensive and available and most home improvement stores), to disperse water and prevent erosion.
That's it, you're done! While splashblocks are one solution, there are several other methods to safely capture or infiltrate rainwater. Look for these in future Green Your Drainage posts!
For more information, check out the Seattle RainWise website. Also, several cities now offer downspout disconnection programs - check with your local municipality to see what might be available.