Protecting Water Quality with Septic System Rules

Susan Slack, Principal Planner, Lakes Region Planning Commission

The information contained in this article is not intended as legal advice and may no longer be accurate due to changes in the law. Consult NHMA's legal services or your municipal attorney.

Water quality is a high priority in New Hampshire’s Lakes Region.

Actually, that’s probably the case everywhere, but it has particular resonance in the Lakes Region, which is home to the four largest lakes located entirely within the state’s borders, six of the 10 largest New Hampshire only lakes, and more than 273 lakes and ponds of all sizes.

Lake setting

And, of course, there is Lake Winnipesaukee – at 44,586 acres, it is by far the state’s largest water body.


Lake Winnipesaukee


Squam Lakes


Lake Winnisquam


Newfound Lake


Lake Sunapee


Ossipee Lake


Lake Wentworth


First Connecticut Lake


Conway Lake


Merrymeeting Lake


Lakes located in the Lakes Region


Lake Umbagog (7,850 acres) and Great East Lake (1,768 acres) straddle the NH-Maine border


In the Lakes Region, water quality means quality of life.

 As people do everywhere, we rely on it to supply our drinking water, but water quality is also the foundation of the Lakes Region’s tourist economy – boating, swimming, fishing, loons, and more.

For Moultonborough, a town of 4,089 year-round residents and more than 24,000 summer residents, water quality protection is a guiding principle of its Master Plan and land use regulations. Located in the Lakes Region, Moultonborough has 89 linear miles of shoreline, the most of any municipality in New Hampshire. In addition to portions of Lake Winnipesaukee and Squam Lake, there are numerous ponds, rivers, streams, wetlands, and aquifers. Moultonborough citizens have sought to protect their natural resources through public outreach and education, land conservation, and zoning measures to regulate stormwater and to protect wetlands, groundwater, shorefronts, floodplains, and steep slopes.

Moultonborough is also partnering with the Lakes Region Planning Commission (LRPC), the Lake Winnipesaukee Association (LWA), and the NH Department of Environmental Services (NHDES) to protect water quality from the public health risks posed by failing septic systems.

With the endorsement of the Moultonborough Planning Board and Conservation Commission, LRPC received grant funding, through NHDES, from the Environmental Protection Agency under Section 604(b) of the Clean Water Act to create a replicable septic system improvement model to address nutrient loading from aging or failing septic systems. Nutrient loading is a nonpoint source of pollution that contributes to water quality impairments. Poorly functioning septic systems can release excessive amounts of nutrients, pathogenic organisms, and pharmaceuticals into a water body.

In addition to a septic system risk analysis, the project includes the development of a model ordinance and a toolkit of education and outreach materials for use by other municipalities and property owners. It will include information about nutrient loading from aging septic systems, best practices for maintaining and operating septic systems, and cost-sharing opportunities for septic system evaluation, repair and replacement programs.

Septic System Risk Analysis

A septic system risk analysis was undertaken as part of the grant project. The analysis focused on properties within 250 feet of the shoreline of Moultonborough Bay Inlet, a densely developed shorefront area that has exhibited the highest levels of in-lake total phosphorus of the eight sub-basins that comprise Lake Winnipesaukee. The goal was to determine how many old (older than 25 years) and potentially failing septic systems there were within 250 feet of the shoreline. For the purposes of the analysis, 25 years was determined to be the average life span of a septic system. The analysis eventually focused on 230 parcels under a half acre with buildings constructed prior to 1992. As of June 2018, only nine of those septic systems had been replaced.

Nutrient loading (phosphorus) was estimated using the LLRM Septic System Nutrient Model, which bases estimates on factors such as age of the septic system, seasonal or year-round use, and average number of occupants. Because there is high seasonal use of Lake Winnipesaukee shorefront properties, it was assumed that the number of people per dwelling was 3.5 instead of the 2.5 value normally used in the LLRM. The nutrient load for parcels under a half acre (280) was estimated to be 44 kg/yr. For all parcels within 250 feet of the shoreline (680) the nutrient load was estimated to be 91.3 kg/yr.

Though it is an estimate, the nutrient load model can be used to support the need for septic system regulations.

Public Health Regulation

Because failing septic systems release excessive amounts of nutrients, pathogenic organisms, and pharmaceuticals into surface water and groundwater, they are a public health risk, and the municipal authority to regulate them is based, not in the zoning power (land use regulations are generally prospective in nature), but in RSA Chapter 147, which governs nuisances. RSA 147:10 prohibits septic systems that are injurious to the public health, and RSA 147:1 grants authority to municipalities to enact regulations to prevent and remove public health nuisances.

The process for enacting health regulations involves approval of the municipal health officer and the governing body (Board of Selectmen/town or city council) after publication of the regulation in a local newspaper or posting in two or more public places in the town. Although RSA 147:1 doesn’t expressly require a public hearing, opportunities for public comment are important, and a significant public education and awareness effort is highly recommended before final adoption.

Once a septic system has failed, RSA 128:5 authorizes the municipal health officer to require a remedy, and NHDES rules require failed septic systems to be remedied within 90 days. But what requirements should a health regulation include to prevent septic system failure?

In 2013, Meredith, another Lakes Region town located on the shores of Lake Winnipesaukee, enacted a health ordinance that requires evaluation of all septic systems within 250 feet of Lake Waukewan that do not have on file an approved operational permit.  Lake Waukewan is the source of Meredith’s public water supply system and is a regional recreational resource.

The Meredith health ordinance requires septic systems to be replaced under the following circumstances:

  1. In instances where there is a valid subsurface system design approval on file with the NH Department of Environmental Services and when a Building Permit Application includes a proposal to increase the number of bedrooms (either by adding bedrooms or converting rooms to additional bedrooms) that exceeds the number of bedrooms included in the NHDES subsurface system approval:
  2. In instances where there is no valid subsurface system design approval on file with the NH Department of Environmental Services and when a Building Permit Application includes a proposed expansion of the building that would either horizontally or vertically create or increase the area of living space,
  3. In instances where there is no valid subsurface system design approval on file with the NH Department of Environmental Services and when a Building Permit Application includes a proposed expansion of a building or new structure that would increase the area of lot coverage (e.g. new garage),

In the first two instances, the Building Permit Application must include a valid NHDES Construction Approval and, before the town will issue an Occupancy Permit, a valid NHDES Operational Approval must be obtained. In the third instance, the Building Permit Application must include a valid NHDES Construction Approval.

It can be difficult to gain public support for regulations that require replacement of septic systems because of the cost burden involved for the property owners, but Meredith partnered with LWA to implement a program to help fix failing septic systems. LWA was awarded a Source Water Protection grant by NHDES to reimburse property owners half the cost of a professional evaluation of their septic systems. Seven septic systems were found to be in failure (44%), and nine passed the evaluation (56%).  Eight Meredith properties had their septic system evaluations done outside of the program, and half were found to be either in failure or passing with intermittent use only.

A second cost-share program was offered for the installation of new septic systems. It provided property owners with $4,000 toward the overall cost of replacement. By the end of 2015, 14 septic systems were upgraded and replaced, resulting in a reduction of 5.3 kg of phosphorus to Lake Waukewan, in addition to a reduction in other pollutants, such as bacteria, nitrates, and pharmaceuticals. 

The Meredith Zoning Ordinance was also amended to establish the Lake Waukewan Watershed Overlay District in which the minimum lot size is either 2 acres or the minimum lot size of the underlying zoning district if it is more restrictive than 2 acres. Where lots are not created but dwelling units are created (duplexes, multi-family, condominiums), the 2-acre minimum or the more restrictive minimum of the underlying zoning district is the required density per dwelling unit.

On the Seacoast, a different approach toward septic system regulation was taken by Rye. The town’s health ordinance requires septic tanks to be pumped out once every three years and applies only within the boundaries of the Parsons Creek Watershed. Owners of residential properties occupied by two or fewer people and owners of properties used only seasonally can apply to the building inspector for a waiver of the three-year pumping requirement. Waivers are prohibited for non-residential properties, or for any property in the designated Impaired Surface Water Quality Zone.

Back in Moultonborough, a committee made up of planning board, conservation commission, and selectboard members, along with town administrators and representatives from LRPC and LWA, has been hard at work to determine the best approach for regulating septic systems in their town. They are discussing a health regulation that would phase in its requirements over time, perhaps including evaluation and replacement, if warranted, prior to closing on real estate transactions involving existing residential or commercial property, and/or, when a building permit is sought for expansion in the number of bedrooms or bathrooms in a residential or commercial building.

Hurdles for Municipalities

One of the hurdles municipalities face when seeking to craft a health ordinance regulating septic system pumping, repair, or replacement is the availability of data on existing systems. Prior to 1967, New Hampshire did not require permits to construct and operate septic systems. As of 2015, the NHDES approval and permitting process is electronic. Municipal property tax cards and the NHDES Subsurface One Stop electronic database, which now includes permit data dating back to 1986, can provide information on construction and operational approval dates for septic systems, but municipal tax map and parcel numbers have changed over the years and often don’t match the information in the NHDES One Stop database. In Moultonborough, prior map and lot numbers had to be researched. To obtain information from NHDES’s paper archives (1967 to 1986) a form is required for each individual property. Information gathering is time consuming and can be impractical.

Another hurdle for Moultonborough’s consideration of linking septic system evaluation and possible replacement to real estate transactions is that New Hampshire municipalities don’t have authority to change the state’s real estate closing or deed recording laws to require septic system evaluation prior to closing. Without a change in state law, this aspect of the local health regulation will need to rely on the town’s education and awareness programs, as well as administrative tracking of real estate closings and a grace period for after-the-fact evaluations.

Other states have enacted laws to regulate septic system inspection or to enable municipal regulation. For example, the Massachusetts Environmental Code (310 CMR 15) requires what is commonly known as a Title V septic system inspection whenever a property is sold, divided, or combined, or when there is a change in use or expansion of the facility. Rhode Island adopted a Septic System Maintenance Act (RIGL Title 45) that enables municipalities to require septic system inspection.

New Hampshire is not without septic system regulation. There are statutes regulating septic system installers (RSA 485-A:36), requiring property owners to properly operate and maintain septic systems (RSA 485-A:37), requiring property owners to receive septic system approval before building expansion or conversion to full-time occupancy if the load on the system would increase (RSA 485-A:38); requiring owners of developed shorefront property with septic systems to obtain a site assessment by a septic designer to determine if the site meets the current standards for septic disposal systems. This latter statute requires the site assessment study form to become part of the purchase and sale agreement, but it doesn’t require either the seller or purchaser to repair or replace a failing or failed septic system.

New Hampshire law could be more effective in preventing the health risks from failing septic systems. Legislation creating a Shoreland Septic System Study Commission was enacted during the last session of the New Hampshire legislature (House Bill 475). The commission was directed to find ways to solve the problem of inadequate septic systems and identify non-state approved septic systems located within 75 feet of surface waters. The study commission’s final report to the legislature is due before November 1, 2020.

Susan Slack is Principal Planner with the Lakes Region Planning Commission. Susan can be reach via email at or by phone at 603.279.5337.  For those who may remember, Susan was a member of NHMA’s legal staff for 10 years.