N.H. Rev. Stat. Ann. § 33:5

Municipalities which have received orders from the department of environmental services to install sewage treatment works under the provisions of RSA 485-A, or to install a sewerage system or sewage treatment works under the provisions of RSA 485:27, or under RSA 147, or acts amending such statutes enacted in the future, may incur debt by the issue of bonds or notes for the construction of such sewerage systems and treatment works outside the limit of indebtedness prescribed by RSA 33:4. Such debt shall at no time be included in the net indebtedness of the municipality for the purpose of ascertaining its borrowing capacity.