Standing Water on Your Parking Lot? Here's Why It Matters and How to Fix It
Water that sits on asphalt after a storm soaks into cracks and the base, softens the pavement and speeds up failure. Ponding usually comes from low spots, settled areas or flowlines that lost their slope. Small low spots can be patched to grade; larger areas need the asphalt and base rebuilt with proper slope to a drain.
A puddle in the parking lot looks harmless. But asphalt lasts longest when water runs off it quickly. Water that sits on the pavement finds every crack, soaks into the base and starts the process that ends in potholes.
Why ponding damages asphalt
- It feeds the cracks. Standing water has time to soak down into the base.
- It softens the surface. Pavement that stays wet wears faster under traffic.
- It spreads. Wet base settles, which deepens the low spot, which holds more water.
- It is a slip hazard for people walking to their cars and on accessible routes.
What causes it
- Areas that settled over time or over an old utility trench.
- Flowlines that lost their slope or were never built to grade.
- Drains that are clogged or set too high.
- Overlays that buried the original slope.
How it gets fixed
- Clean the drains first. Sometimes that is the whole problem.
- Patch small low spots to grade so water moves again.
- Rebuild larger areas by removing the asphalt, repairing the base and paving back with slope to the drain.
- Add or adjust drains where water has nowhere to go.
Then protect it
Once water runs off again, keep the cracks filled every year so water can't get in. Our article on crack filling vs sealcoat explains why that habit does the most to make asphalt last.
How we help
We fix ponding, rebuild flowlines and repair, pave and maintain parking lots across Greater Los Angeles. Send us a photo after the next rain, and call (800) 606-3880.
Sources
JFPEC field practice.