September 2022: Do You Know Where Your Septic Tank Is?

New to having a private septic tank? Wondering how your septic tank works or even where it is? It’s common for New Hampshire homeowners to be unaware of their septic tank’s location or how care for it properly. Neglecting your septic tank can lead to costly and burdensome repairs, so it’s important to know where it is, how it works and how you can better care for it.

Where's My Septic Tank?

To start out, there are some places that your septic tank should not be placed, like next to your well, below or touching your home, under a patio or deck or under a paved surface. A septic tank’s location can impact nearby water sources, as well. A permitted septic system designer will design a system and maintain setbacks to water sources to the greatest extent practical (depending on site conditions), and a permitted septic system installer will install it in accordance with the approved plan. An approval for operation will be issued after inspection. Cities and towns receive copies of septic system plans from NHDES, so your plans should be available at your local city or town office, typically within the Building Division. You can ask for any septic plans and/or approval numbers that they have on file for your property. You can also search for any information on the property through the NHDES OneStop database. If you can’t find your septic system plans through these avenues, you can make an archive record request through NHDES.

Once you have the plan, you can review the septic system diagram to determine the size of your tank and the number of lids it has to help narrow down its location. However, there are cases where records cannot be found. If your home was built before 1967, when the Subsurface Systems law was enacted, these records would not exist. Also, sometimes the systems have been installed without a permit.

If the plans for your septic system are not available, there are still ways to help you identify the location of your septic tank.
First, you should inspect your yard for any extra green grass or flat spots that look out of place compared to the rest of your property. Often, the land above your tank will be leveled out, and sometimes, drain fields and overflowed septic tanks can provide fertilizer to your lawn, making it healthier and greener. If all else fails, you can locate where your sewer line leaves your house (usually in a basement). Follow the sewer line’s path by inserting a soil probe, which can be found at your local hardware store, into your soil every two feet or so; eventually you should find where your sewer line meets up with your septic tank. If this process is difficult, or if you’d like some assistance, you can also contact a septic system service provider to help you locate your septic tank.

So How Does Your Septic System Work?

Every time that water goes down your drain it ends up going through your sewer line and into your septic tank. The tank itself is a buried, water-tight container. The septic tank’s main job is to hold all of the wastewater and allow the solid waste to sink to the bottom; the fats, oils and greases float to the top. The water is then allowed to exit the septic tank and travel through a pipe to the drain field, where the pretreated wastewater is discharged through the soil. The soil then treats and disperses the wastewater, which has now been freed of coliform bacteria and viruses.

When necessary, about every three to five years, you should have your septic tank pumped out so that all the grease, scum and sludge stored in the tank can be brought to a wastewater treatment plant.

Caring for your Septic System

Here are some more helpful tips that will help to keep your septic system efficient and effective and may even prolong the life of your septic tank!

• Only flush the Three P’s: pee, poop and toilet paper.
• Consider using plant-based detergents and cleaners.
• Don’t put bleach and other harmful chemicals down the drain.
• Have your septic tank regularly inspected.
• Pump your septic tank as needed, normally every three to five years.
• Don’t put solids, grease, or food waste down your sink.
• Keep the area above your septic tank clear of trash, debris, vehicles, or trees.
• Read our fact sheet “You and Your Septic System” for more information!

A septic tank needs to be cared for and serviced. Neglecting your septic system and not treating your septic tank properly can lead to costly and burdensome repairs. So, it’s important to know where your septic tank is, how it works and how you can better care for it.