Septic Systems

On-Site Sewage Disposal (Septic Systems)

The Manchester Health Department plays an important role in protecting public health and the environment through careful planning, permitting, and regulation of on-site wastewater disposal systems. Around 15% of homes and businesses in Manchester rely on individual septic systems to treat and manage wastewater.

Proper septic system design, installation, and maintenance are essential to prevent contamination of soil, groundwater, and surface water—and to protect our community’s health.

Our Responsibilities

The Environmental Health Division oversees all activities related to on-site sewage disposal, including:

Investigating failed systems: Inspecting reports of malfunctioning or failing septic systems and ensuring corrections are made promptly.
Approving new and replacement systems: Reviewing plans, witnessing test pits to determine soil suitability, and inspecting installations throughout construction.
Subdivision review: Evaluating proposed subdivisions to confirm that lot sizes and soil conditions support safe and compliant wastewater disposal before submission to the Planning Board.
Follow-up and enforcement: Tracking all reported failures and ensuring compliance with city and state regulations.

Why Proper Wastewater Disposal Matters

Septic systems provide a cost-effective and efficient way to manage household sewage. However, poorly designed, installed, or maintained systems can release untreated wastewater, contaminating nearby groundwater or surface waters.

These discharges may carry harmful microorganisms, such as bacteria, viruses, and parasites, that threaten both human health and the environment. Ensuring sewage is properly treated and disposed of safeguards drinking water sources and public safety.

Regulatory Oversight

The Manchester Health Department enforces several local and state regulations governing septic systems, including:

State Statutes: RSA 147 and RSA 485-A, which address health hazards caused by failed systems.
City Ordinance: Chapter 53 - On-Site Sewage Disposal in the City of Manchester Code of Ordinances.
State Design Rules: Env-Ws 1000, the New Hampshire Department of Environmental Services’ “Subdivision and Individual Sewage Disposal Systems Design Rules.”

As the local enforcement agent for the New Hampshire Department of Environmental Services (NHDES), the Department ensures compliance with all applicable rules and permits.

Program Insights

Over the last several years, Manchester has seen few new septic system installations, but a steady number of inspections, replacements, and maintenance activities.

Common factors influencing system failure or replacement rates include:

Development on marginal sites or areas with changing water table conditions
Impacts of climate change on seasonal groundwater levels
Aging infrastructure and new system technologies
Real estate trends, including property transfers requiring system updates
Sewer line extensions connecting former septic-system properties

With these factors remaining stable, the Department expects the program's resource needs to remain consistent in the near future.

Minimum Lot Size Requirements

Before installing a new system or subdividing property, please review the city’s Minimum Lot Size Requirements for On-Site Sewage Disposal Systems (PDF) to ensure adequate land area and soil conditions.