N.H. Rev. Stat. § 485-A:37
Any person who has installed or otherwise acquired a subsurface sewage or waste disposal system installed in accordance with the provisions of this subdivision is required to operate and maintain said system in such a manner as to prevent a nuisance or potential health hazard due to failure of the system. Failure to so operate and maintain shall be considered a violation of this chapter and shall be subject to the penalty as provided in RSA 485-A:43, IV. The department or its duly authorized agents are authorized to enter any and all premises at all reasonable hours for the purpose of inspecting and evaluating the maintenance and operating conditions of subsurface sewage or waste disposal facilities. As circumstances warrant, the department or its duly authorized agents are empowered to issue compliance orders in writing under the provisions of this section. Nothing in this section shall be construed to limit or modify the authority conferred upon the department or local health officers under the provisions of RSA 147 or upon local officials certified by the department under the provisions of RSA 485-A:42.
RSA 485-A:37
1989, 339:1. 1996, 228:106, eff. July 1, 1996.