How To Fix a Wet Lawn and Causes of Soggy Areas in Grass

It could happen anytime. Maybe you’re mowing your lawn. Maybe you’re playing with your kids in the yard. You might even just be casually surveying the lush greenery you’ve so carefully cultivated.

Then, you notice it. A large wet spot or even brown spots. It hasn’t rained recently, and as far as you’re aware, no one has taken a hose and sprayed down that one area of your lawn.

Could it be your sewer line?

The most common answer is that it probably is.

I’m going to break down the signs that your sewer line is causing the wetness in your lawn – and what to do about it. Then, we’re going to look at some of the many other potential causes of wet spots on your lawn in case the issue isn’t your sewer.

Sounds good? Then let’s get started.

How Easy Can Sewer Lines Crack or Break?

Cracked sewer line

If you live in a city, chances are you’ve got a sewer line running through your yard (those of you with septic tanks, don’t worry – we’ll talk tanks in another section of this post). Nowadays, sewer lines are pretty sturdy – the PVC pipes that are used can last well over 100 years. 

Older sewer lines, on the other hand, can crack a bit more easily. That’s why older homes are more prone to sewage leaks – that, and the fact that the sewer lines will be nearer to the end of their lifespans.

Wear and tear can cause the materials used in the sewer line to degrade, causing leaks. Another major culprit? Tree roots. Tree roots can infiltrate PVC pipes, too, so if you’ve got an old tree on your property and your lawn is mysteriously wet, it’s even more likely the wetness was caused by your sewer line.

Not all lawn puddles are caused by sewer lines, however. Thankfully, there are a few ways that you can check whether or not sewage is the source of the problem.

Is Sewage Causing Damp Spots in your Yard?

sewage Leak in a lawn

The most obvious sign that sewage is what’s causing damp spots in your yard? It smells like sewage. You might also smell mold or mildew. Your other senses can help, too – you may be able to hear a sewer line leak.

One of the most telling signs is particularly interesting for folks as passionate about lawn care as us: your lawn might look particularly lush in the wet areas. That’s because of all the extra fertilizer your lawn is getting from – well, you get the idea.

Tree Roots Causing Plumbing Leaks

tree roots causing leaks

If your lawn is wet and you’re experiencing plumbing problems like slow or no drainage, it’s an almost surefire sign that there’s a problem with your sewer line. Tree roots may have created a blockage in your sewer line. These same roots create the cracks that sewage can leak out from.

The best way to know whether or not your sewer line is the cause of your wet lawn? Call a plumber. They’ll be able to diagnose any problems – best of all, they’ll be able to fix them. And if you’re worried about your lush lawn getting dug up by an excavator, there’s some good news. Sewer line repair has become a lot less invasive over the years. There are new “trenchless” methods that involve installing a lining, so your lawn can be almost, if not entirely, preserved.

Is Your Septic Tank Causing Wet Spots?

septic tank leaks

A malfunctioning septic tank, just like a sewer line, can cause wet spots on your lawn. More often than not, these wet spots will be found around your septic tank and drain field, though they can be near the line which transports sewage to your septic tank.

We won’t talk too much about the line that brings sewage from your home to the tank because they’re the same problems we’ve already covered above. Septic tanks, however, have their own set of potential problems.

The drain field is failing

clogged drain field

There are a lot of different things that can cause your drain field to fail. An excess of rainfall can oversaturate the soil. The drain field may also have been improperly installed.

Let’s talk about lawn care and drain fields. When you’re looking for advice on how to lay sod, you’ll often be told you want to add new soil. You want to be especially careful doing this in your drain field. The level of soil in drain fields is measured very carefully in order to absorb and filter wastewater. If you add too much, your septic tank may not work properly.

You basically want to be careful any time you’re doing lawn care in your drain field. You can generally aerate without any problems – drain lines can be as few as 6 inches below the surface, but most aerators only go about 3 inches deep. Digging, on the other hand, can quickly lead to drain line damage, which in turn leads to leaks. 

All this is to say, that if you’ve been doing yard work around your drain field, a damaged drain line or the wrong level of soil could both create wet spots.

Call a septic service professional

If you suspect your septic tank is the cause of your wet lawn woes, you know what to do – call a professional. In best case scenarios, even your drain field can be rescued. The lines going to and from the tank can also be repaired.

A side note on drain field pH

If you’ll allow, here’s a quick side note that has nothing to do with wet spots. The pH of your drain field will often be slightly higher than the pH of your surrounding soil. That’s because household waste is alkaline – the septic tank itself does a good job of eliminating most of this alkalinity, but it doesn’t always get to the point that wastewater is neutral. 

As such, if you’re planting a new lawn, opt for grasses that don’t prefer acidic environments. Avoid grasses like fine fescues. If you want to test the pH of your drain field’s soil, check out our review of the best soil pH tester kits

Other Causes of Wet Lawn Syndrome

If the cause of your wet spots isn’t sewage, you’re in luck – sewer line and septic tank repair can be very expensive. The other causes of wet lawn syndrome are almost always much less pricey to fix. There are quite a few possible non-sewage causes – let’s look at some now.

A failing grade in your lawn

grading issue

Your wet spots could be a landscaping problem. If there are raised or lowered spots on your lawn, level them out. You can do this with little more than a shovel, soil, a compactor, and seed. 

A much more labor-intensive possibility is that your lawn isn’t properly graded – this could lead to water stagnating around your property. That’s going to cause a lot more problems than just wet spots on your lawn.

When you regrade, you’ll basically need to redo your entire lawn. On the bright side, it will be an excellent opportunity to try a new mixture of grasses.

A water main break

Water main break

Water main breaks, like sewer line breaks, can cause wet spots. The grass in these spots won’t grow particularly lush and spongy, however, and you’re (thankfully) not going to notice the smell of sewage.

The downside to a water main break over a sewer line break is that you’ll very quickly notice it in your wallet – your water bill will skyrocket. Depending on where you live, you may also be fined by the local water authority. Call a plumber and get the damage assessed and repaired as quickly as possible. 

Compacted Soil problems

If your soil is highly compacted, has a shallow depth before bedrock, or has a lot of clay, it may not absorb water very well. This can lead to wet spots persisting days after the rain has stopped.

Sprinkler System Leaks

Sprinkler system leaks

There could be a leak in your in-ground sprinkler system or moveable sprinkler setup. The easiest way to spot this type of leak is to look around your lawn where the underground sprinkler pipes are and see if any area is greener or is holding water. That should tell you there is a leak in the sprinkler pipes. Replacing an entire system can be costly but patching up the leak will be much cheaper if you don’t mind getting your hands dirty and using a shovel.

And with that, we’ve covered all the most common sources of wet spots on your lawn. If you have any questions at all, or you’d like to mention another possible source creating wet spots in your yard, feel free to leave a comment below!

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