7 Critical Checks for Parking Lot Drains

Proper drainage is an essential part of preserving pavement. Check these 7 things regularly to prevent expensive water damage and make a safer parking lot.

Judson Burdon
Posted by Judson Burdon on May 26

Water can be both beneficial and disadvantageous to parking lot owners and managers. Water can be used to clear off mud, sand, fallen leaves, twigs, and any other form of vegetation and debris that clutter the parking lot’s surface.

On the other hand, water can also be a hazard if not drained properly. Shallow puddles that didn’t drain off completely can cause the surface to become very slippery. Vehicles can skid out and cause property damage, collision, and injuries to unsuspecting pedestrians. Do you own or manage a mobile home park or a car dealership? A rain-slick pavement can also cause tenants or customers to slip and fall, which can lead to lawsuits against you and your property.

Both scenarios will not only cost you money, but also your reputation among your customers and tenants. How you take care of your parking lot reflects how much you care for them, which is why having a properly installed drainage in your parking lot is essential. It keeps water from puddling after a heavy rain or storm, while preserving the longevity of your pavement.

Aside from regularly cleaning and sealcoating your parking lot, you also need to be sure that your drainage is functioning as intended. Here is a checklist that will help you determine if there is a need to clean or repair your drainage system.

Related: The Rising Risk of Parking Lot Litigation

How to Check Your Drains

1. Is water collecting around the drain?

Ensure that there is no water puddling around the ring. If water gets around the drain, it seeps along the side. When this happens, the pressure builds when it freezes during winter, causing the concrete sleeve to crack.

Drain off excess standing water to prevent any seepage that can cause more damage if left unchecked.

2. Is the asphalt flush with the parking lot drain?

The manhole needs to be flush with the asphalt surface; if it isn’t, you have to do a drain-drop. This means that you have to cut off a layer or section of pavement around the drain, until the drain’s rim is slightly lower or at the same level with the surrounding pavement.

This is to ensure that rainwater or water from hoses when cleaning the parking lot surface gets drained accordingly. Failing to do this can cause water to pool around the drain (cited in the first example above) and can cause flooding, as well as other potential long-term damages.

3. Need a patch?

If the asphalt has just settled and the ring is popping up above the grade, a simple asphalt patch can fix this issue. Make sure to tamp down well enough until the patch is compact and leveled so that it doesn’t create a collar that prevents water from getting drained off properly.


4. Anything inside the drain?

Inspect the inside of the drain – if there are build-ups due to fallen debris, vegetation or gunk and starts to smell, there is some draining issue. You need to get it cleared so it doesn’t create a mosquito nest. 

Test with water in a hose or several five-gallon pails, and see if it drains out.  If it doesn’t, call a professional pumping and cleaning company to drain it and find the blockage.


5. Is there loose aggregate?

Check around and inside the drain for accumulated loose pieces of aggregate material and sand. If your parking lot is near a highway or road, or if it is slightly lower than the main road or freeway, this loose debris might be brought along by runoffs after a heavy rain. However, it is best not to leave things to chance.

Check to see if there are sections in your lot that are crumbling or cracking. Clean those sections and repair accordingly. Small debris loosened from cracks or potholes can accumulate within the drains when washed off by rainwater and can cause clogging.

6. Does water pool in the center of the parking lot?

Parking lots are generally designed to slope slightly from one end to facilitate proper water discharge. In addition, it is also constructed to have a high point or “crown” to ensure that water gets directed away from the center of the parking lot, and into the proper drainage channels.

If water pools in the center and does not drain off as it should, this means that the “crown” has begun to sag due to various factors. It is possible that the foundation has been eroded which results in sagging, or the central section has unrepaired potholes that trap the water, thus, preventing it from running off to the sides.

We recommend to check and make necessary repairs to avoid repaving.

7. Are nearby drains blocked?

Check drain inlets that lead to streets or canals to make sure they are not obstructed by debris or vegetation. Blockage on this stretch of your drainage system can also cause flooding in your parking lot, and further compromise the integrity of the pavement.



Do not wait for extensive damages to happen to your asphalt pavement before taking action. A scheduled walkthrough of your entire parking lot can help you spot potential problems before they can get worse. For large-scale damages that are beyond DIY repair methods, we recommend to seek professional help to avoid causing more harm than good to your property.

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Topics: Asphalt Maintenance, Property Management

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