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Patio Flooding When It Rains? Add a Drain Before Water Pools

A patio that holds water usually has no slope and no exit. Find the low spot, fix what you can for free, then add a drain that carries the rest away.

By Jamilur Rahman Updated November 5, 2026 · 6 min read

Time
Half a day
Cost
$50-$150
Difficulty
Medium
A shallow puddle covering part of a wet paver patio next to a back door after rain
In this guide
  1. Quick answer
  2. Free vs. permanent fix
  3. What you'll need
  4. Why it happens
  5. Try this first (free)
  6. When free fixes aren't enough
  7. Buy the fix
  8. Channel drain or catch basin: pick by the shape of the puddle
  9. Standing water makes the patio slippery and the yard buggy
  10. What to skip
  11. FAQ
  12. Related problems

Quick answer

To stop patio flooding, find where the water collects, make sure gutters and downspouts stop dumping on it and level any sunken pavers. If water still pools, set a channel drain along the low edge, or a catch basin at one low spot, and pipe it to a lawn or storm outlet. A patio that keeps flooding has water with no exit, so the drain gives it one.

Free fix vs. permanent fix

Free fix · 1 to 2 hours

Find the low spot and move the roof water

  • Run a hose to find where water stops
  • Clear leaves and silt off the patio and out of gutters
  • Point downspouts onto the lawn, away from the patio
  • Relevel any sunken pavers

How long it lasts: Enough for light rain. A patio that sits flat or slopes toward the house will still pool in a heavy storm.

Most readers choose Permanent fix
Patio channel drain with a grate (illustration)
Illustration

A patio channel drain with a grate

A channel drain is a slim trough with a grate that sits flush with the surface. It catches water across the low edge of the patio and sends it down a pipe to a place it can go. That fixes the cause, no exit, instead of just chasing puddles.

What to get: Patio channel drain with a grate

How long it lasts: Years, if you clear the grate each season.

Check price on Amazon

As an Amazon Associate I earn from qualifying purchases.

What you'll need

  • Garden hose

    Run it on the high side to see where the water goes

    You have it

  • Long level

    Checks slope across the patio; use it on a straight board

    You have it

  • Push broom

    Clears leaves, silt and sand from the surface and drain

    You have it
  • Our pick
    Patio channel drain with grate (illustration)
    Illustration

    Patio channel drain with grate

    A slim trough that catches water along the low edge

    Check price
  • Square catch basin with grate (illustration)
    Illustration

    Square catch basin with grate

    For one low spot where water sits

    Check price
  • Solid drain pipe and fittings (illustration)
    Illustration

    Solid drain pipe and fittings

    Carries water from the drain to the outlet

    Check price

Why it happens

1

A patio that is flat or slopes toward the house

A patio should fall away from the house by about 1/4 inch per foot. A flat or reversed slope has nowhere to send the water, so it sits.

2

Settled pavers or slabs

The soil under a few pavers sinks, leaving a dip that fills with water and keeps the stones wet long after rain.

3

Roof water landing on the patio

A downspout that empties near or onto the patio adds a whole roof's worth of water to the surface.

4

A blocked or missing drain

An old drain full of leaves, sand and silt cannot take water. In many patios there is no drain at all.

5

A yard that slopes toward the patio

Higher ground above the patio sends runoff onto it in a hard rain.

Try this first (free)

Do these in order, starting with the simplest.

  1. Run the hose test

    Tool used: Garden hose

    Run a hose on the high side of the patio for several minutes and watch where the water goes. Mark the spot where it stops moving and pools. That is your low spot.

  2. Check the slope

    Tool used: Long level

    Lay a long, straight board across the patio and put a level on it. The surface should drop about 1/4 inch per foot away from the house. If it drops toward the wall or sits flat, a drain is the fix.

  3. Sweep the patio and clear the drain

    Tool used: Push broom

    Sweep leaves, sand and silt toward the lawn, not into a drain. Clear any existing drain and rinse it out, and clean the gutters above the patio.

  4. Redirect downspouts

    Make sure each downspout ends on the lawn or a garden bed, at least 4 to 6 feet from the patio and the house, using an extension if needed.

  5. Relevel sunken pavers

    Lift the sunken pavers, add compacted base material and a layer of sand to raise the spot, and set them back. Filling a dip with loose sand on top will wash away.

When free fixes aren't enough

If the patio is a flat slab, slopes toward the house or sits in a low corner of the yard, no amount of sweeping fixes the shape. A channel drain along the low edge handles a wide area, and a catch basin handles one dip. Both need a pipe to a place the water can go. Call 811 before you dig, and never send the water against the house foundation or onto a neighbor's property. If water enters the house or basement, or you see wet foundation walls or new cracks, call a pro. That is a bigger problem than a patio.

Buy the fix

Still stuck after the free fixes? These are the products we would look at.

Our picks compared
PickProductFixesWho it's forBuy
Best pick
Patio channel drain with a grate (illustration)
Illustration
Patio channel drain with a grate
a patio that floods along a whole edge or at a door threshold Patios that collect water across a wide area or along the house wall. Check price
Budget pick
Square catch basin with a grate (illustration)
Illustration
Square catch basin with a grate
one low spot where water sits A single dip, corner or step where water collects. Check price
Best pick
Patio channel drain with a grate (illustration)
Illustration

Patio channel drain with a grate

Fixes: a patio that floods along a whole edge or at a door threshold

Look for: Sections long enough to span the low edge; A grate rated for foot traffic and furniture; An end outlet that fits 4-inch pipe; Narrow grate slots that do not catch heels or chair legs.

Who it's for
Patios that collect water across a wide area or along the house wall.
Honest downside
The water pools in one small dip. A catch basin is cheaper and simpler.
Check price on Amazon
Budget pick
Square catch basin with a grate (illustration)
Illustration

Square catch basin with a grate

Fixes: one low spot where water sits

Look for: A grate that sits flush with the pavers; An outlet that fits 4-inch pipe; A sturdy plastic body.

Who it's for
A single dip, corner or step where water collects.
Honest downside
Water spreads along the full edge of the patio. A single basin will not catch it all.
Check price on Amazon

As an Amazon Associate I earn from qualifying purchases. We don't show prices because they change, so use the button to see today's price.

How we picked: How we picked: this page is based on patio drainage and paver installation guides, slope recommendations from landscaping extension services, and the pooling problems and fixes people report in owner reviews. We do not test products by hand.

Channel drain or catch basin: pick by the shape of the puddle

  • Water along a whole edge or a door threshold: a channel drain.
  • One dip or corner: a square catch basin.
  • Both a dip and a wide area: a channel drain along the edge, with the dip leveled.

Standing water makes the patio slippery and the yard buggy

Water that sits on a patio grows algae, which makes the surface slick, and it gives mosquitoes a place to breed. Drain it within a day or two. If algae has already formed, scrub it off before you set any drain.

What to skip

Sealers, and drains that dump at the foundation

A surface sealer does not move water, and a puddle will still form. A drain that empties against the house wall or into a neighbor's yard just moves the flooding to a worse place.

Frequently asked questions

Why does my patio keep flooding?
Most often the patio is flat or slopes toward the house, a few pavers have sunk, a drain is blocked or a downspout empties onto it. A hose test shows which one is to blame.
How much slope should a patio have?
About 1/4 inch per foot away from the house is the usual target, and not less than about 1/8 inch per foot. Check yours with a level on a straight board.
Where should a patio drain empty?
Away from the house onto a lawn or garden, into a dry well or to a storm drain where your local rules allow. A sanitary sewer is usually not allowed.
Can I add a drain to an existing patio?
Yes. For pavers, lift a row along the low edge, dig the trench and set the drain. For poured concrete you need to cut a slot, which is heavy work, so many people hire a contractor.
Do I need a permit for a patio drain?
Some areas require one for drainage changes. Call 811 before you dig and ask your local building office about discharge rules.

As an Amazon Associate I earn from qualifying purchases. Affiliate disclosure

Patio channel drain with a grate (illustration)
Illustration

Our pick: Patio channel drain with a grate

Check price