RSA 72:12-a — Water and Air Pollution Control Facilities. –

I. Any person, firm, or corporation which builds, constructs, installs, or places in use in this state any treatment facility, device, appliance, or installation wholly or partly for the purpose of reducing, controlling, or eliminating any source of air or water pollution shall be entitled to have the value of said facility and any real estate necessary therefor, or a percentage thereof determined in accordance with this section, exempted from the taxes levied under this chapter for the period of years in which the facility, device, appliance, or installation is used in accordance with the provisions of this section. This paragraph shall not apply to privately-owned landfills or ancillary facilities located at such landfills or to sewage disposal systems installed pursuant to RSA 485-A:29 through RSA 485-A:44 and rules adopted pursuant thereto, except that any exemption for a sewage disposal system granted prior to January 1, 2010 shall remain in effect.
II. The party seeking the exemption shall file an application with the department of environmental services if the exemption sought is for a water pollution control facility or an air pollution control facility, with a copy to the taxing authorities in the municipality where the facility is situated. Said application shall describe the facilities and their function or functions and shall state the applicant's total investment therein and the portion allocable to each function.
III. The department shall investigate and determine whether the purpose of the facility is solely or only partially pollution control. If the department finds that the purpose of the facility is only partially pollution control it shall determine by an allocation of the applicant's investment in the facility what percentage of the facility is used to control pollution. In making its investigation, the department may inspect the facility and request such other information from the applicant as is reasonably necessary to assist it in making its determination.
IV. Upon making its determination, the department shall notify the applicant and the taxing authorities of the municipality where the facility is situated whether the purpose of the facility is solely pollution control, or, if not, what percentage of the applicant's investment in the facility should be allocated to pollution control.
V. The taxing authorities shall each year separately appraise and describe the facility and related real estate and cause such appraisal and description to appear in their inventory. In accordance with the provisions of this section, the taxing authority shall exempt from the taxes levied under this chapter the appraised value of the facility and any real estate necessary therefor, or the exempt percentage thereof, determined by the department. The exemption period shall begin as of the April 1 next following the receipt of the department's determination.
VI. Either the municipality or the owner of the facility may request a rehearing or appeal from such determination in accordance with the provisions of RSA 541.