Why do cities want downspouts disconnected?

In cities with combined sewers, roof water from connected downspouts adds to the load during storms, which can cause sewer overflows and basement backups.

Is downspout disconnection required?

In some places, yes. Detroit’s water department says state law requires disconnecting downspouts from the combined sewer, and St. Louis MSD treats connected downspouts in combined-sewer areas as a code violation. Check your local rules.

How much does it cost to disconnect a downspout?

Detroit’s water department estimates about $40 for most houses if you do it yourself. Some cities and utilities offer free help or materials.

Where should a disconnected downspout drain?

Onto a lawn or planted area several feet from the house that slopes away from the foundation, not onto a neighbor’s property or a walkway.

Disconnecting Downspouts: City Programs Explained

Disconnecting downspouts from the sewer: city programs explained

In many older cities, roof downspouts run straight into the sewer. During heavy storms that water helps overload the system and can back up into basements. Here is why cities want downspouts disconnected, what several programs offer, and how to do it without creating new problems.

By Local Gutter Network · Updated September 30, 2026

Why downspouts were connected in the first place

For decades, many cities required downspouts to be piped into the sewer. The City of Chicago explains that its old code required gutter downspouts to be connected to a house’s private sewer drain. In cities with combined sewers, which carry both sewage and stormwater in the same pipes, that meant roof water from every house went into the system during every storm.

When a big storm fills those pipes, the water has to go somewhere. It overflows into rivers and lakes, or it backs up into basements. That is why many older cities now encourage, pay for, or require disconnection.

What some cities offer

Program details and budgets change, so always check the current rules with your city or utility.

Detroit: the Detroit Water and Sewerage Department says residents are required by state law to disconnect downspouts leading to the combined sewer. Residential parcels get an automatic 25% drainage-charge credit, which homes without disconnected downspouts may lose in the future. DWSD estimates the do-it-yourself cost at about $40 for most houses.
Chicago: the City encourages homeowners to disconnect downspouts and send water to yards and gardens. The Metropolitan Water Reclamation District has offered free rain barrels to Cook County residents who disconnect downspouts connected to the sewer.
St. Louis: under MSD’s Project Clear, downspouts connected to the combined sewer are now a code violation in affected areas, and MSD has paid to correct connections made when they were still allowed.
Washington, DC: DC Water’s Downspout Disconnection Program disconnects eligible downspouts in its Rock Creek project area, and participants can get a free rain barrel. DOEE’s RiverSmart Homes program helps with rain barrels and rain gardens.
Philadelphia: the Water Department’s Rain Check program offers free rain barrels and helps pay for downspout planters and rain gardens after a workshop.

How to tell if your downspouts are connected

Look where each downspout ends. If it disappears into a pipe in the ground, often a clay or cast-iron standpipe next to the foundation, it may be connected to the sewer or to a separate storm drain. A downspout that ends in an elbow on a splash block or extension is already disconnected. If you are not sure where an underground pipe goes, ask your utility or a plumber before you change anything.

How disconnection works

A typical disconnection, as described by DC Water and Detroit’s program, looks like this:

Cut the downspout a few inches above the standpipe.
Cap the standpipe so debris and water cannot get in.
Attach an elbow and an extension that carries water away from the house.
Direct the water onto a lawn, garden or other area where it can soak in, or into a rain barrel with an overflow that also drains away.

Many programs require specific steps or inspections to qualify for credits or free materials, so read the rules first.

Doing it without creating new problems

Keep water away from the foundation. The discharge point should be several feet from the house on ground that slopes away. Otherwise, disconnecting just moves the water from the sewer into your basement.
Mind your neighbors. Do not send water onto a neighbor’s property or a shared walkway.
Think about winter. The City of Chicago reminds homeowners that cold weather causes icing. Keep discharge off sidewalks and driveways.
Handle overflow from rain barrels. A full barrel overflows in every storm. Route the overflow away from the house.
Check the lot. Some lots are too small or too flat to disconnect safely. Programs often exempt those, and an installer can suggest alternatives.

New gutters are the right moment

If you are replacing gutters anyway, plan the downspout locations around where the water should go, not just where the old standpipes are. Adding a downspout or moving one to a corner with a lawn can make disconnection easy. Larger 3x4-inch downspouts also clog less and move water faster. See downspouts and drainage and gutters overflowing in heavy rain.

When you cannot disconnect

Not every lot can take the water. Row houses with no yard, homes on very small or flat lots, and downspouts that would discharge onto a sidewalk or a neighbor’s property are common problem cases. Many programs recognize this and exempt such properties or offer alternatives. Options include:

Rerouting the downspout to another corner of the house where there is lawn
A longer extension or buried line to a safe discharge point, where local rules allow it
A rain garden or planter that holds and soaks up the water
Leaving a connection in place where the program or utility says it is the safer choice

Talk to your utility or city before making changes if you are unsure. Some cities also have rules about discharging water toward the street or public sidewalk.

Who can do the work

Many disconnections are simple enough for homeowners, and programs like Detroit’s explain the steps. A gutter installer can do it as part of a new gutter job, and a plumber may be needed if the underground pipe also carries other drains or needs a proper cap. If the downspout is being moved or the gutters are being replaced, it is usually easiest to have the gutter installer plan the new outlet locations with disconnection in mind.

Check before you dig

If a disconnection plan includes burying a drain line to carry water farther from the house, call 811 before digging so underground utilities are marked. Keep buried lines sloped so they drain, give them an outlet that will not freeze shut or erode the yard, and make sure the discharge point meets your city’s rules.

Rain barrels: useful, with limits

A standard rain barrel holds about 55 gallons. That fills quickly during a heavy storm, so a barrel reduces runoff in small rains but does not replace a proper discharge path. Use a barrel with a screened top, a spigot for watering and an overflow hose that leads away from the foundation. Empty it before big storms if you can.