Septic System Installation 101: A Beginner’s Guide for New Homeowners
TL;DR: If you're a new homeowner in a rural or suburban area, you may need to install a septic system instead of connecting to a city sewer line. The septic system installation process involves soil testing, system design, permitting, excavation, tank and drainfield placement, and final inspection. This beginner's guide explains each step in detail, helps you understand the role of the system, and shows you what to expect as you plan for a successful installation.
So you just purchased your new home, or you’re building in an area without municipal sewer access, and you need a septic system that can handle all your wastewater needs. While the concept may sound intimidating, simply understanding the basics of a residential septic system installation will give you the confidence to manage the process with ease.
A septic system collects wastewater from your home's toilets, sinks, showers, and appliances, then treats and disperses the water safely underground. Knowing how it works and what goes into installing one is the first step to improving your system’s efficiency and keeping it fully compliant with local regulations.
What is a Septic System?
A septic system is essentially a private wastewater treatment system. It consists of two main parts: a septic tank and a drainfield (also called a leach field). The septic tank holds and separates solids from liquid waste. The clarified water then flows into the drainfield, where it safely filters through soil.
For new homeowners, it’s important to understand that a properly installed and maintained septic system can last 20 to 40 years or more. But that longevity starts with the right installation process.
Step 1: Site Evaluation and Soil Testing
Every septic system installation starts with evaluating the land. A licensed septic designer or site evaluator will visit your property to perform a test pit or percolation test. This test measures how quickly your soil absorbs water and determines the type and size of system your property can support.
The results of this test are critical. If your soil doesn't drain well, you'll need a more complex system like a raised bed or mound system. If your groundwater is too close to the surface, that will also affect your design and permitting requirements.
Step 2: System Design
Once the site is evaluated, the next step is to create a septic system design based on your soil type, home size, local code requirements, and layout of your property. This includes decisions about:
Septic tank size
Drainfield type and location
Pipe lengths and slopes
Setbacks from wells, buildings, and property lines
In New Hampshire, and many other states, only a licensed septic designer can submit plans for approval. The system must meet both state and local health department regulations before moving forward.
Step 3: Permitting
Before any construction begins, you must get permits. The approved design is submitted to the state environmental department and your local town or city. This process may take anywhere from a few days to a few weeks depending on the complexity of the system and the town's permit backlog.
If you are building a new home, your septic system approval is usually one of the first items needed before foundation work can begin. Your septic contractor will typically handle the paperwork and submission process.
Step 4: Excavation and Site Preparation
After receiving the necessary approvals, installation begins with excavation. A professional crew will clear the designated area, dig the trench for the septic tank, and excavate space for the drainfield. This is a significant part of the septic system installation process and may impact trees, landscaping, or other features on the property.
The crew will also grade the area to ensure proper water flow from your home to the tank and through the rest of the system. Proper slope is essential to prevent backups and ensure the system works by gravity, or in some cases, pressure.
Step 5: Installing the Septic Tank and Drainfield
The septic tank is typically made of concrete, fiberglass, or polyethylene and is placed in the ground according to your approved design. Once it is leveled and connected to the home’s plumbing, the distribution box and drainfield are installed.
The drainfield consists of a series of pipes or chambers laid over a gravel or stone bed. The system allows water to gradually filter back into the soil without contaminating groundwater. Depending on your soil conditions, your drainfield may be a shallow trench, bed system, or raised mound.
Step 6: Backfilling and Final Inspection
After installation, the system is inspected by local or state authorities to ensure it matches the approved plan and was built to code. This inspection verifies tank placement, pipe layout, slopes, and other important details.
Once the system passes inspection, the excavation is backfilled and the area is graded for proper drainage. The site may be reseeded or left ready for landscaping.
How Long Does Septic System Installation Take?
The timeline for residential septic system installation depends on several factors:
Soil testing and permitting: 1–3 weeks
Excavation and installation: 3–5 days
Final inspection and backfilling: 1–2 days
In total, the process typically takes 2 to 4 weeks from evaluation to final approval, assuming no delays with permitting or weather.
Maintenance Tips After Installation
Once your system is installed and running, it’s your responsibility to maintain it. That starts with pumping your tank every 3 to 5 years, using water efficiently, and never flushing harmful items like grease, wipes, or chemicals.
Regular septic tank maintenance can prevent early system failure and costly repairs. Many homeowners also opt for regular inspections, especially in the first few years of use, to catch any issues early.
Choosing the Right Installer
If you're a first-time homeowner, working with a knowledgeable, transparent contractor can make all the difference. A qualified professional will walk you through your options, help with permits, and ensure that the system is installed to last.
Townes Septic has decades of experience working with new homeowners in southern New Hampshire. Our team provides start-to-finish support, from soil testing and design to full installation and inspection.
Get Started with Septic System Installation
If you need a new septic system or are planning to build a home, now is the time to start planning. Contact Townes Septic to learn more about the installation process and how we can help you get it done right from the start.