Parking Lot Drainage Problems

How effectively water drains from your company’s parking lot may not initially be top-of-mind in your business plans. However, one heavy rain and you’ll quickly see how parking lot drainage problems can cause trouble for you and your customers.

While the problem of parking lot drainage may seem overwhelming, business owners today have a number of options that can efficiently and effectively correct poor parking lot drainage.

Three reliable parking lot drainage solutions are: 

  1. Adding internal curbing
  2. Correcting the parking lot’s slope
  3. Installing drains

Drainage problems can not only be bad for the aesthetics and lifespan of your asphalt, but they can also be expensive to repair if left unattended. Besides, no customer wants to walk through three inches of standing water before they get to your business, so don’t make them do that. 

Fix Your Drainage Problems Now

You may need only one of these solutions, or you may want to exercise all three, depending on the location of your parking lot and the extent of the damage caused by poor drainage over the years. 

Be sure to consult a professional with knowledge of your specific situation, and determine which drainage solution(s) is right for you. 

Drainage Solution #1: Add Internal Curbs

Adding curbing within the boundaries of your parking lot can help redirect the flow of water through the asphalt. This can limit standing water and push the water toward the perimeter of the lot, where it can be reabsorbed into the natural earth. 

As a bonus, curbs can also provide opportunities to accent your parking lot with light landscaping, which will make your business look more professional. 

Drainage Solution #2: Correct The Parking Lot Slope

Water pooling in your parking lot signifies that your parking lot either doesn’t have a slope, or it’s sloping the wrong way. To correct this, you need to adjust the slope of your parking lot so that the parking area very gradually slopes off to the edge of the lot perimeter. 

This will help prevent any water from pooling on the asphalt by directing it to flow off the premises instead. 

To most effectively drain water off your parking lot, the slope of the asphalt should be between 2% and 5%.

Drainage Solution #3: Install Drainage Ditches And Grates

Another common solution to drainage problems is to add runoff drains and trenches throughout your parking lot. This may be a better option if your parking lot is especially large, to the point where redirecting the water may be too challenging to realistically accomplish.

By installing drainage ditches and grates in your parking lot, you’ll ensure the water is directed out of your parking area and into a sewer or other municipal waterway. 

To make sure the standing water runs into drainage gutters, the grade of the drainage grate should be at least 3% but preferably closer to 5%. 

An asphalt parking lot with striping and drainage system.

Why Do Parking Lots Tend to Have a Lot of Puddles And Standing Water?

In short, it all comes down to poor water drainage. 

Have you ever pulled up to your grocery store, dentist’s office or local gym on a rainy day, only to find the entire lot flooded with standing water? While this may initially seem like a minor inconvenience, the truth is that all that water is bad for business. 

Unfortunately, many businesses have these parking lot drainage problems, and many consumers have experienced something like this at one location or another. 

Keep reading to learn more about why parking lot drainage is so important and what causes it.

A different cars parked on concrete parking lot with striping guides.

Why Parking Lot Drainage Matters

Adequate drainage in your parking lot is important because it prevents water from pooling on the pavement. Having a water-free parking lot:

  • Ensures your parking lot asphalt lasts longer
  • Makes a good first impression on your customers
  • Keeps parking spaces free from puddles so employees and customers can park easily
  • Keeps customers and employees safe from potential slips and falls
  • Prevents unsanitary standing water from lingering in your parking lot
  • Shows detailed consideration and planning on your part

Having a properly draining parking lot will not only keep your business property in good condition, but will also enhance opinion about your business in your customers’ and employees’ eyes. 

What’s more, not addressing potential drainage problems as soon as you notice them can lead to expensive, time-consuming remedial work later. The sooner you resolve your drainage problems, the better off your business will be. 

Now that you know why proper drainage is important, let’s consider what causes pooling problems in the first place. 

What Causes Parking Lot Drainage Problems?

Uneven ground is generally the culprit behind poor parking lot drainage. When the ground slopes unevenly in your parking lot, rainwater and water runoff follows the path of the slope, which causes pooling.

Sometimes this can be the fault of a previous paver’s oversights, but more often than not it’s simple wear and tear on the asphalt over the years or an issue with the evenness of the underlying earth. 

Regardless of the reason, it’s important to identify and resolve drainage issues as soon as possible. 

A black car parked on wet asphalt parking lot.

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How Do You Identify Drainage Problems?

The telltale signs of poor parking lot drainage are:

  • Pooling water in your parking lot
  • Leftover debris like sand or pebbles in random places on the pavement
  • Residual, dusty-looking patches throughout the lot where the pooling water has evaporated

If you notice one or more of these signs occurring on your asphalt, it’s highly likely that you have parking lot drainage problems. To prevent problems with your asphalt in the future, you should start preparing to remedy the situation. 

Unfortunately, it’s possible that the poor drainage is already affecting your lot. The following are signs that the standing water is already causing damage to your asphalt:

  • You see cracks in the asphalt surface. This is caused when water puts pressure on the asphalt.
  • The top layer of asphalt has started to “ravel.” This happens when water erodes the top layer of your parking lot over time. 
  • The asphalt looks like it’s bleeding. This means that the asphalt binding agent has risen to the surface of the pavement, indicating aggregate separation.
  • Frequently traveled sections of the lot are starting to rut. This looks like the asphalt is sinking in slightly on itself, and will occur in sections of the lot where people drive most often. Commonly, asphalt rutting looks like tire impressions. 

If you notice these issues and warning signs, be sure to speak with a parking lot drainage expert as soon as possible. Not taking action could result in severe consequences, which we’ll explain in detail next. 

A damage asphalt parking lot.

What Are The Consequences of Not Having Proper Drainage?

If your parking lot is retaining water, it’s best to deal with the situation sooner, rather than later. 

If the lot is part of a newly purchased property, you might not know how long drainage has been an issue. Speak with a professional to evaluate the extent of the potential damage and get a quote for what a drainage solution might cost. 

As mentioned above, there are a number of reasons why proper parking lot drainage is important. When these considerations haven’t been included in the original design of your parking lot, you will experience both direct and indirect consequences. 

In general, we can break these consequences down into two categories: damages and expenses. 

1. Damages From Parking Lot Drainage Problems

A good asphalt pavement will hold up for 12-15 years before it needs maintenance. However, if your pavement collects a lot of standing water due to poor drainage, that timeframe could be significantly reduced. 

Standing water can seep into and exacerbate existing cracks and holes in your asphalt. Such damage can occur both during the paving process, as well as long after its completion. 

Warning Signs Before Paving

Before construction and paving begin on your parking lot, you can assess how likely your lot is to encounter drainage problems by looking at the would-be lot’s location. If your parking lot is located at the base of a hill or on low-lying land, it’s likely that you’ll have drainage problems. 

Additionally, aside from problems caused directly by flooding, land that has experienced heavy water retention over the years is likely to have less stable soil, which can indirectly impact your parking lot over time. Unstable soil has a tendency to settle and shift over the years, which could result in uneven dips in your asphalt, even if the initial paving was done correctly.

While moving the location of the parking lot may not be an option, knowing this information early will help you determine how important parking lot drainage solutions will be for you and your customers. 

Damages Possible After Paving

While addressing any potential drainage problems before your lot is constructed is important, you won’t be out of the woods just because the asphalt has been laid. 

If pooling water recurs frequently or is left unattended for extended periods of time, the water can seep down to the pavement base, causing long-term damage. Once the base course of your parking lot is damaged, its ability to withstand regular traffic will decrease, causing further potholes and cracks. 

Not only do such eyesores look unseemly to customers, but they can be expensive to fix. This brings us to our second category of poor drainage consequences: the price to fix them.

2. Cost of Parking Lot Drainage Problems

When drainage problems are allowed to persist in your parking lot, they can end up costing you a pretty penny. 

Even simple asphalt repairs at a person’s home can cost between $979 and $3,521, let alone the cost to repair huge sections of a parking lot for your business. 

Additionally, many commercial pavers charge per foot of space that will need paving. This means that letting drainage problems persist and worsen over time can have severe consequences for your wallet.

For example, a 2019 article estimates the average cost for repaving an asphalt lot to be between $1.49 and $1.69 per square foot. This means that if your entire lot has suffered from drainage problems, you could easily be looking at spending upwards of $10,000 to get it fixed. 

Aside from the direct costs of repairing your parking lot, an unsightly parking area can cost your business indirectly, too. A 2017 report from the traffic data research company INRIX found that 40% of drivers in the U.S. have avoided driving to locations where they know there are parking challenges. 

So, if you want to address your drainage problems before they become too expensive, what can you do? Thankfully, there are several ways you can improve the drainage of your parking lot. 

A tar and chip parking lot with yellow paint numbers guide.

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Why You Should Fix Your Drainage Problems

Your customers may not actively notice a parking lot that has no problems, but you can be sure that they’ll notice if it’s full of cracks, potholes and standing water. 

Presenting a smooth, evenly paved asphalt parking lot to your customers starts off their experience with your business on the right foot. 

By identifying and addressing your drainage problems, you can ensure that your customers have a good experience with your brand from the moment they pull up in front of your building. 

Not only will a consistently professional experience encourage patrons to become returning customers, but having good parking lot drainage will also save you future headaches and maintenance costs

Improve Your Parking Lot Drainage Problems Before They Get Worse

Poor drainage in parking lots is a compounding problem. That is, the damage caused by your drainage issues will only continue to get worse until you resolve them. 

Now that you know the ins and outs of how to identify drainage issues, what causes them and what solutions you have at your disposal, get in touch with one of our experts today to stop further water damage before it starts. 

Your customers and staff will thank you.