It’s best not to have to hunt for your septic tank after it fails or when it’s overdue for a cleanout. Knowing your septic tank’s location is critical when it’s finally time for repairs. Read our guide for tips on how to find your septic tank quickly and how to probe for a septic line.

---

Why Should I Locate My Septic Tank?

It’s easy to ignore a septic system when it’s working well, but knowing where it is can save you time and stress if it fails. Finding your septic tank now may help you with the following:

• Avoiding accidental damage: Renovations or big landscaping projects could damage your septic tank, and knowing its location can help you to avoid this.
• Helping to boost your property value: Potential homebuyers may want to know that you’ve done proper septic tank maintenance. Having a system that’s accessible and well-maintained can be a selling point.
• Helping you spot issues earlier: Keeping an eye on the area around your septic tank can alert you to potential issues such as slow drains, standing water, or bad smells in your drain field.
• Making maintenance easier: Homeowners should have their septic tank pumped every three to five years, depending on the number of people in the household. Knowing where the tank is located makes septic tank service simpler and potentially less expensive.

Finding your septic tank can make life easier and ensure that the septic system operates smoothly for a long time.

---

Factors Determining Septic Tank Placement

Taking time to understand the variables of septic tank installation, such as environmental regulations can make it easier to locate your property’s septic tank. Consider the following factors when searching for your home’s septic tank:

Property Layout

Your septic tank must be at least 5 feet away from your home and is usually 10 to 25 feet away. This distance is to prevent the septic tank from contaminating your house’s foundation.

Local Regulations

Local building codes and regulations play a big role in septic tank placement. These laws protect groundwater from contamination and ensure that your septic tank sits away from wells, property lines, and waterways.

Soil Considerations

Your septic system relies on the surrounding soil to absorb and filter wastewater. Soil type, drainage rates, and slope all influence placement. Contractors should have buried septic tanks in loose, sandy loam instead of in clay soil, which could lead to backups.

Water Table Depth

The water table is the groundwater level beneath your property’s surface. A septic tank that sits too close to a high water table could contaminate groundwater or even well water with effluent.

A qualified septic system professional will consider these factors and your future needs when placing the tank.

---

How To Probe a Septic Line

Probing a septic line is a common do-it-yourself (DIY) method for finding the top of the tank. Gather the tools below before starting your search.

• Flags or markers: These can help you mark the spots that you’ve probed, which are potential sites of the septic tank.
• Hammer: This can help you drive the probe into hard or compacted soil.
• Soil probe: This is a long, thin metal rod with a pointed tip. It’s usually about 3 or 4 feet long and can slip into soil easily. If you don’t have a soil probe, use a piece of rebar.
• Tape measure: You’ll use this after finding the location of the septic tank to note its placement.

Contact your local utility service by dialing 811 before you start a probing project. Ask a representative to detail the exact locations of underground utilities such as gas lines or electrical cables. This will help you avoid making accidental contact with the lines, which could be dangerous.

Steps To Probe a Septic Line

1. Find the main sewer line that exits your house from the basement or crawl space, which is usually a PVC pipe that’s 4 inches in diameter. This sewer pipe connects your home to its septic tank. Follow the main sewer line outside to the point at which it exits the foundation. You should be able to track the line by walking straight away from your home.
2. Start probing at least 5 feet away from your house in a straight line that follows the likely sewer line path. Insert the probe into the ground and gently push it down. You may need to gently hammer the end of the probe if the soil is hard or compacted.
3. Take stock of any resistance as you push the probe, but don’t push the probe too forcefully. You’re looking for a concrete or fiberglass septic tank lid and you don’t want to accidentally damage it.
4. If you don’t feel any resistance, pull out the probe and move over about 2 feet. Repeat the process by inserting the soil probe while feeling for resistance. Remember that there’s no consistent depth for a septic tank. It may be a few inches or several feet underground. Keep working in a gridlike pattern as you move away from the house.
5. Once you hit something solid, probe around the area to determine how big the item is and whether it’s large enough to be your septic tank lid. Mark the edges of the object with your flags. Remember that a septic tank lid is usually round or rectangular.
6. Use this same method to help you find the likely location of your leach field. This is where wastewater filters through the soil before joining the groundwater supply. Use a similar probing pattern, moving outward from the septic tank location in the direction of water flow. If you detect some hollowness under your probe, it’s a good indication that your drain field is in that area.

Probing isn’t foolproof. Septic tanks may be too deep to reach with a soil probe, and rocky soil may make finding your tank difficult. However, you have a good chance of locating your septic system if you follow these steps.

---

Identifying Septic Tank Lids

Septic tank lids are usually round or rectangular and 2 feet wide. Potential lids should sit 5–25 feet away from your house and will follow a straight line from the main sewer pipe exit.

Septic tank lids are typically made of one of the materials below.

• Concrete: You’ll find concrete lids on septic tanks for older homes. Heavy lids may have inset handles or a lip to help open the hatch.
• Plastic: Modern septic tanks have green or black plastic lids. They may have built-in handles or lifting keyholes.
• Precast concrete with hatch: Some concrete tanks have steel or plastic access hatches in the concrete lids. You’ll typically find latching mechanisms to help you open them.

If you think you’ve found a septic tank lid, don’t immediately try to pry it open yourself. A broken lid is a safety hazard and may require expensive repairs. Mark the lid so everyone in your house will avoid it.

---

Professional Help for Locating Septic Tanks

If you have trouble finding the septic tank with a DIY search, consider another option.

Using Official Documentation

Check for any documents that may point to the location of your home’s septic tank:

• Property records and building permits: Your local building department might have local county records of your septic system installation, including diagrams and permit applications that point out the tank’s placement.
• Inspection paperwork: Inspection paperwork might contain a sketch of the wastewater system or septic tank map. The former homeowner may have left these details for you.

Don’t be afraid to ask neighbors about the potential septic tank location. If they’ve lived in the area for a long time, they might recall where contractors installed the septic tank or where professionals have since serviced it.

Calling in Professionals

Locating older tanks can be tricky. Professional plumbers have specialized equipment such as metal detectors and ground-penetrating radar that can pinpoint your septic tank’s exact location and depth.

The cost of hiring a septic company to find your tank varies depending on required labor and equipment but is usually $100–$450. A more detailed inspection may cost up to $700.

*Cost data in this article sourced from Angi.

---

Our Conclusion

Part of being a responsible homeowner means knowing the location of your septic tank. A properly maintained septic system protects your health, property value, and the environment. If you aren’t sure where your septic tank is located, try out a DIY probing method to help you find it. If that doesn’t work, check for official documentation or hire a plumbing professional.

---

FAQ About Locating a Septic Tank

Are septic tank locations public record?

Septic tank locations may be public record in some areas. Check with your local building department or local health department to find out.

What determines the location of a septic tank?

Factors that determine the location of your septic tank include the location of your foundation, soil conditions, and local regulations.

How do you probe a septic line?

You can probe a septic line by finding the main sewer line in your basement or crawl space and locating where it exits your house. Follow the path in a straight line 5 feet from the foundation, insert a soil probe into the ground, and test for resistance. Continue probing the soil in a grid pattern and use flags to mark where you’ve probed.

What does a septic tank lid look like?

A septic tank lid is usually made of concrete or plastic and is circular or rectangular. It’s generally about 2 feet across.

When should I seek professional help to locate a septic tank?

If you can’t locate your septic tank using the probing method or by checking official paperwork, seek the help of a septic system professional. A basic septic system inspection, which includes finding the septic tank lid, usually costs $100–$450.

To share feedback or ask a question about this article, send a note to our Reviews Team at reviews@thisoldhousereviews.com.