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How To Find a Sewer Line Underground [5 Methods Explained!]

Looking to install new sinks or toilets? Or maybe you’ve dropped your favorite watch on the sink. Beautifying your washroom or locating precious items doesn’t come that easy. You need to locate your underground sewer line.

How to find a sewer line underground?

You can do it yourself by utilizing a pipe locator. Additionally, you can request the zoning office of your city to locate the lines for you. Furthermore, you can find success contacting the previous owners of your property. Following exit areas of piper or drains can also yield successful results.

This is simply a basic summarized concept. Please browse through this essay if you want to learn more in-depth. 

I’ve written a thorough guideline detailing the process in 6 steps. If this interests you, read along!

So, what are you waiting for? Let’s delve right into it!


An articulate sewage system is undoubtedly a blessing for us. But often homeowners find it hard to locate their sewage lines. 

Locating a sewer pipe is essential, especially in the case of installing utility sinks in garages or toilets. This keeps the contaminated water away from pure water. 

But, this isn’t an easy task. That’s especially the case if you want to go all DIY. In this article, I will clearly explain all the ways you can find your underground sewage lines. 

By the end of this article, this complex task will be very difficult for you to accomplish. 

4 Methods of Locating Sewer Lines Underground

There are several methods that you can utilize to accomplish your goals. I have listed them below.

Method 1: Pipe Locator

Start off by setting the frequency. Both the transmitter and wand need to have the same frequency. 

Locate a drain or a sewer nearby. If you have an outdoor sewer, locate a white or black pipe. This pipe usually has a plastic cap. 

These will lead you straight to the underground sewer line.

Next, feed the line into the drain. Extend it up to 15 feet. Now use the wand vertically. 

Move the tip frontwards and backward, occasionally, rotate it as well if you’re receiving weak signals.

If the beeping signal of the wand gets louder, you’re coming closer to your destination. If the beeping is the loudest, you’ve found the end of the line.

Keep in mind that you can frequently find rodents as well after locating the pipe. That’s why it’s wise to install rodent-proof pipe insulation.

Once you’ve found your desired point, there might be a possibility for the sensor to read a false positive or true negative. 

This might be a sensitive issue if you’re drilling inside the pipe. So additionally, you can perform the low sensitivity test. 

To re-confirm your finding, try lowering the sensitivity. I prefer lowering the sensitivity by 3/4th the original sensitivity. 

Try locating the strongest signal again. If this matches with your previous finding you’ve confirmed your spot.

The next course of action is to mark the spot. Place a utility tape along the line of beeping. 

Then, place a utility flag where the beeping is loudest. This will indicate that the sewer line is directly beneath it.

Now that you’ve solved the problem, take a look at our pipe locator recommendations:

Product 1
Product 2

These pipe locator machines will show you accurate findings. This will hasten the process and save you time.

Method 2: Check With The Zoning Office of Your Locality

The zoning office is usually in possession of a utility map. They have an accurate idea of where utilities and services are located in your area. 

The zoning office should be able to tell you which sewer line connects to your household.

But, some zoning offices, especially in rural areas, won’t be able to locate these.

If contacting the zoning office is possible, this is a great option as it also saves your budget. 

Method 3: Check with the Previous Owner

When in doubt, it’s always wise to pick up your phone. It’s very likely that the previous owners of your idea have a great idea of where underground sewers are located. 

It’s possible that you don’t have their contact information. 

But, don’t worry I’ve got that covered as well. It’s possible to find the contact information of the previous owners by looking through your municipal records.

Method 4: Locating Manholes

Manholes are usually located at a distance of 100 feet from each other. Underground sewer lines can be found between manholes. 

Try to find manhole covers that are very easy to spot. This will solve your problem as you can locate the sewer lines from there.

If all of these methods seem too intricate, the best option is to contact professionals. There are several advantages to this. 

For example, they know double vanity plumbing installation techniques.

First of all, DIY methods have the risk of drilling through pure water lines. These risk factors can be avoided utilizing the technical expertise of professionals.

Secondly, utility locator contractors are also very affordable to hire. You won’t have to spend too much on expensive locating tools.

These methods should be adequate enough to accurately locate underground sewer lines. If you face any problems along the way, contact a plumber immediately. 

Best of luck!


Question: How much does a pipe locator cost?

Answer: Pipe locators cost somewhere above $900 in stores. You can also find pipe locators online. But, keep in mind the extra charges of delivery. You might also have to pay shipping fees. So online purchases can be estimated to be $1,000 or more.

Question: Are there any law implications related to locating sewer pipes underground?

Answer: Yes, if you’re digging to locate or connect to sewer lines in the US. You are legally required to call 811 before any sort of digging. This is to prevent any sort of underground utility damage.

Question: Are sewer cameras viable?

Answer: Sewer cameras are very costly. Their prices range anywhere from $1,500 to $30,000. Additionally, a decent level of expertise is also required. You can opt for affordable plumbing services if you are running on a budget.


That’s all we have on “how to find a sewer line underground”. We hope our article helped you solve your problem! 

We hope our article has been of value to you and has helped you through this.

Take care of yourself, and of course, your sewer line. 

Best of luck!