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 48