N.H. Rev. Stat. Ann. § 540: § 540:13-e

I. In this section:
(a) "Infestation of bed bugs" means the presence of bed bugs in real property rented for residential purposes.
(b) "Remediation" means action taken by the landlord that substantially reduces the presence of bed bugs in a dwelling unit for at least 60 days.
II. The landlord shall bear the reasonable costs of remediation of an infestation of bed bugs, but may recover those costs if the tenant is responsible for the infestation.
III. If a landlord alleges that a tenant is responsible for an infestation of bed bugs, the landlord may bill the tenant, in writing, for the reasonable costs of remediation of the infestation of bed bugs in the tenant's own unit. If within 30 days of the completion of remediation the tenant has not paid the landlord for the reasonable costs of remediation, or entered into a repayment agreement with the landlord, such failure shall be considered grounds for eviction for nonpayment of rent pursuant to RSA 540:2, II(a).
IV. In an eviction action for nonpayment of rent based on failure to pay the reasonable costs of remediation, or in an action for damages for the reasonable costs of remediation of an infestation of bed bugs, the landlord shall bear the burden of proving both that the tenant was responsible for the infestation and that the landlord offered the tenant the opportunity to enter into a reasonable repayment agreement.
V. In an eviction action for nonpayment of rent based on failure to pay the reasonable costs of remediation of an infestation of bed bugs, or in an action for damages for the reasonable costs of remediation of an infestation of bed bugs:
(a) Notwithstanding paragraph IV, there shall be a rebuttable presumption that the tenant is responsible for the infestation if during the 6 months prior to the inception of the defendant's tenancy, and throughout the defendant's tenancy, there were no reports, to the landlord or a municipal health or housing authority, of the presence of bed bugs in the defendant's unit or the dwelling units of a multiple-unit building that are adjacent to or directly above or below the defendant's unit, or by previous tenants in a single-family home. For the purposes of this subparagraph, the defendant's own report to the landlord or a municipal health or housing authority shall not be considered a report.
(b) In evaluating which party is responsible for the infestation, the court shall consider the totality of the evidence, including but not limited to the following:
(1) The existence and extent of bed bugs in other units or common areas anywhere in the building prior to and during the tenant's tenancy;
(2) In which unit bed bugs were first discovered;
(3) Whether and to what extent, prior to the infestation that is the subject of the litigation, the landlord undertook remediation efforts in the tenant's unit and the units adjacent to and directly above and below the tenant's unit; and
(4) Whether the tenant had bed bugs in the dwelling unit in which he or she resided immediately prior to moving to the unit that is the subject of the litigation.