Septic Systems

Ensuring proper design and installation to protect public health and the environment.

To prevent pollution in public and private waters, septic systems must be properly designed, installed, operated and maintained. We review your proposed design plans and specifications for septic systems to ensure proper siting, construction and operation. 

After we (and if required, your local municipality) approve your proposed plans, we issue you an Approval for Septic System Construction. Before you use your septic system, you need both an Approval for Construction and an Approval for Operation. Plans for proposed septic systems must be designed, prepared and submitted by someone we authorize.

Septic system application forms and files can be found on OneStop.

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Many changes to systems require Approval for Construction 

An approval for construction must be obtained prior to converting a structure from seasonal to full-time occupancy, prior to increasing the load on an existing septic system and/or commencing any additions to a structure; replacement, expansion or relocation of a structure, subject to the requirements of RSA 485-A:38, II-a. 

Approval status  

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An inspector will determine whether the system meets requirements 

A NHDES inspector will inspect the newly-constructed septic system and evaluate the system to ensure that it has been installed in accordance with the intent of the approved plan. Once the inspector has determined that the system meets all applicable requirements, an electronic Approval for Septic System Operation will be completed with a digital copy maintained by NHDES.  

Regional Inspectors  

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Guidance and permit applications for septic systems 

A septic system is required for any structure from which wastewater will be discharged on site and to which a water supply is or will be connected. Properly designed, installed and maintained, your septic system should give you many years of trouble-free service. NHDES provides guidance for submitting applications, which can also be submitted online through e-permitting.    

Find the applications  

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Can't find what you're looking for?

Can't find what you're looking for?

Use our website search by typing in keywords like “site assessment,” “well release” or “local approval.”

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Did you know?

Did you know?

Septic systems installed near water may require additional permitting with the Shoreland Bureau, check the Consolidated List of Waterbodies Subject to the Shoreland Water Quality Protection Act to see if a Shoreland permit is needed.

Trainings and Certifications 

We issue permits to septic system designers and installers to ensure they properly design and install effluent disposal systems. We also host certification exams, as well as required continuing education. For details, visit the Septic Designer and Installer Certification page.

For Continuing Education Seminars, see the Approved Seminar List.

Archive Records

The Subsurface Systems law was enacted in 1967, so records do not exist if the structure was constructed prior to 1967. From 1967 to 1971, state records mainly consist of those septic systems installed within 1,000 feet of a surface water. The catalog of these records is not always complete. From 1967 to 1986, state records consist only of paper records. The municipality where the structure is located may have either paper or electronic records. From 1986 to present, state records consist of paper and some electronic.   

Submit an Archive Request
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Did you know?

Did you know?

If you suspect a violation of NHDES septic regulations, you can submit an official complaint form to NHDES Land Resource Management (LRM) for investigation into the alleged violation. File a complaint  

For general septic system questions and Reviewer of the Day