Standing water on concrete

It matters for three reasons at once. Saturated concrete is the precondition for freeze-thaw damage, so ponding accelerates surface deterioration in a cold climate. Standing water grows algae and becomes slippery. And ponding usually means the fall has gone, which is a geometry problem that will not improve on its own.

The useful work is establishing whether the slab was built without adequate fall or has lost it, because that determines whether lifting can fix it.

What it is

Exterior flatwork is built with a deliberate slope so water leaves. When that slope is absent, reversed, or interrupted by a low spot, water collects and stays until it evaporates or soaks away.

Ponding is either original or acquired. An original low spot has been there since the pour and tends to be a single localised dish. An acquired one follows settlement and tends to sit where the ground beneath has moved — often near a downspout, a trench line or the house.

The depth is less important than the duration. Water that clears in an hour is very different from water still there two days later, because contact time drives the damage.

What seeing this cannot establish

• The presence of ponding does not tell you whether it is original or acquired, and that distinction determines the options.
• Nothing visible establishes whether there is a void beneath a settled low spot.
• Ponding on a slab does not establish that water is reaching the foundation, and its absence does not establish that it is not.

What this can be associated with

Candidate explanations, not findings. Nobody can establish which applies to your concrete without seeing it.

• Settlement creating a low spot, which can be associated with backfill consolidation, a trench line, or base washout
• Fall that was inadequate when built, so the slab drains slowly even undamaged
• Curled panel edges creating a dam at a joint
• Downspouts or surface water delivering more water than the slope was designed to shed
• A raised edge, new landscaping, or an added step blocking the original drainage path

What you can safely check yourself

• Photograph the puddle at its full extent and mark the outline with chalk once it dries. That outline is your low-spot map.
• Measure the depth at the deepest point with a ruler and note it.
• Time it. Note how long after rain the water is still there. Duration is the number that matters.
• Lay a level across the ponding area in two directions and photograph, to establish whether the slab falls the wrong way or is simply flat.
• Note whether the low point is near a downspout, a service trench, or the house.
• Check whether the water is on the slab or against a wall. Water against a wall is a different and more consequential finding.

When this is frequently cosmetic

• Shallow ponding that clears within a few hours, away from the house, on a slab in good surface condition
• A minor low spot in a mild climate with no salt exposure and no slip concern

When professional evaluation matters more

• Water ponds against the house, a foundation wall, or a garage door
• The area stays wet for more than a day after rain
• Surface deterioration — scaling, pitting, spalling — is concentrated in the ponding area
• The ponding is new or growing, which indicates settlement rather than original geometry
• The area is a walking route and becomes slippery

When replacement enters the conversation

• The required change in fall is more than lifting can deliver across the area
• The slab has broken up around the low spot
• Surface deterioration in the ponding area is already extensive

Evidence worth having before you ask for estimates

Every item here is something you can produce without tools or risk, and every one of them makes an estimate more accurate.

• A photograph of the puddle at full extent plus a chalked outline once dry
• Depth at the deepest point, and how long it persists after rain
• Level readings in two directions, photographed
• A note of downspout and surface-water discharge points
• Whether the water reaches a wall or door

Questions to ask whoever comes out

• Was this slab built with enough fall, or has it lost it? What are you measuring?
• Can lifting restore the fall here, or is grinding or replacement the realistic option?
• What fall will I have when you are finished and how will you verify it?
• Does the roof drainage need changing so this does not simply recur?
• If the low spot is filled rather than lifted, how will the patch weather compared to the rest?

Where estimates for this commonly differ in scope

These are the places two prices for apparently the same work stop being comparable.

• Filling a low spot, grinding a high edge and lifting a settled area produce similar drainage outcomes by different means with different appearance and lifecycle consequences.
• Drainage work upstream of the slab is usually a separate trade and usually the cheaper half of the solution.
• "Level" and "draining" are not the same target, and only one of them keeps water off the concrete.

Who tends to do this work

• A drainage contractor or landscaper who does grading
• A concrete leveling specialist
• A residential flatwork concrete contractor

ConcreteOwner does not inspect, certify or approve contractors. This describes which trade usually holds this work, not a recommendation of anybody in particular.