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Fix a downspout that backs up

We'll clear the downspout, check the outlet, and tell you when to call a plumber.

Troubleshooting · Home plumbing
15–30 min
What you'll need
  • Hose
  • Plumber's snake (if needed)
Step 1 of 4

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Steps

Goal: Clear the downspout and drain outlet.

  • Flush the downspout from the top or bottom. Remove debris.
  • Check the drain outlet. If it connects to an underground drain, snake it.
  • Good: Water flows. Bad: Call a plumber.

Clear downspout

Goal: Remove blockages from the downspout.

  • Flush with a hose. Use a snake if needed.
  • Good: Backup cleared. Bad: Check the outlet or underground drain.

Check outlet

Goal: Clear the drain outlet. Where the downspout discharges—ground, splash block, or underground—must be clear. If it connects to an underground pipe, snake it or call a plumber.

  • Good: Outlet clear, water flows. Bad: Underground drain clogged—call a plumber.

When to get help

Call a plumber or drainage professional if:

  • The downspout connects to an underground drain that will not clear.
  • You cannot access the drain.

Verification

  • Water flows through the downspout during rain.
  • No backup at the gutter connection.

Escalation ladder

Work from the device outward. Stop when the problem is fixed.

  1. Clear downspout Flush from top or bottom; remove debris.
  2. Check outlet Clear the drain outlet; check the connection.
  3. Snake underground drain If connected to underground drain, snake it.
  4. Call a plumber Underground drain will not clear—call a plumber or drainage professional.

What to capture if you need help

Before calling support or posting for help, have these ready. It speeds everything up.

  • Downspout condition
  • Outlet condition
  • Underground connection (if any)
  • Steps already tried

Is the downspout clogged?

Debris in the downspout is the most common cause of backup.

Flush the downspout from the top or bottom. Remove debris. Clogged: flushing should fix it. Clear: check the drain outlet and underground connection.

Yes No

You can change your answer later.

Clog was the cause

Clearing the downspout should fix the backup. Clean gutters and downspouts at least twice a year.

Done

Does the downspout connect to an underground drain?

Underground drains can clog and cause backup.

Check the drain outlet. If it connects to an underground pipe, that pipe may be clogged. Snake it or call a plumber. If it discharges to the ground, ensure the outlet is clear.

Yes No

You can change your answer later.

Call a plumber

Call a plumber or drainage professional if: the downspout connects to an underground drain that will not clear, or you cannot access the drain. Snaking may need a pro.

Done

Reviewed by Blackbox Atlas

Frequently asked questions

Why would a downspout back up?
Common causes: debris blocking the downspout, a clogged drain outlet, or a blocked underground drain pipe. Leaves and debris are the most common cause.
Can I fix a downspout backup myself?
Yes. You can clear the downspout and the drain outlet. Flush with a hose. If the downspout connects to an underground drain that is clogged, a plumber or drainage professional may need to snake it.
When should I call a plumber for a downspout?
Call a plumber or drainage professional if: the downspout connects to an underground drain that is clogged, or you cannot clear the backup by flushing. Snaking an underground drain may need a pro.

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