Ariz. Rev. Stat. § 33-2107

A. A landlord may charge separately for gas, water or electricity by doing either of the following:

1. Installing a submetering system.

2. Allocating the charges separately through a ratio utility billing system.

B. If a landlord charges separately for gas, water or electricity by installing a submetering system:

1. The landlord shall provide a separate meter for every user.

2. For each billing period the cost of the charges for the period shall be separately stated, along with the opening and the closing meter readings and the dates of the meter readings. Each bill shall show the computation of the charge generally in accordance with the serving utility company billing format for individual service supplied through a single service meter.

3. The landlord shall not charge more than the prevailing basic service single family residential rate charged by the serving utility or provider and any other fees and taxes imposed on the landlord by the provider relating to this rate.

C. If a landlord charges separately for gas, water or electricity pursuant to a ratio utility billing system:

1. The landlord may recover the charges imposed on the landlord by the utility provider, except that a landlord shall not include a charge by the supplying utility for gas, water or electricity used in a common area or office if the common area or office is separately metered. The landlord shall post in a conspicuous place on the premises the current rate under which the landlord pays for the utility service, as well as the expenses included in the administrative fee and a statement that the total administrative fee charged in the aggregate does not exceed ten per cent of the landlord's total charge during the billing period. For the purposes of this paragraph, "charges" means the landlord's actual expense of obtaining the utility, including the taxes and fees assessed by or through the utility provider and imposed on the landlord by the utility provider.

2. The landlord may charge an administrative fee for the landlord's actual administrative costs. Any monthly administrative fee shall not exceed the greater of the landlord's actual administrative costs or ten per cent of the monthly charges by the utility provider in the aggregate to the landlord. The landlord shall not impose any other additional charges. If the landlord arranges for utility billings to be handled by a third party, the utility billings shall instead include the actual and reasonable cost charged by the third party for the service. Those third party charges shall not exceed ten per cent of the monthly charges by the utility provider for that utility in the aggregate to the landlord. For the purposes of this paragraph, "administrative costs" includes the direct actual costs to the landlord of billing for utilities, including the cost of staff time to calculate and mail the bills, postage and stationery.

3. The rental agreement shall contain a disclosure that lists the utility services that are separately charged to the tenant and shall state that an administrative fee covering the landlord's administrative expenses in making the calculations under the ratio utility billing system will also be assessed. The rental agreement also shall state that total administrative fees assessed each billing period shall not exceed ten per cent of the landlord's total charges for that utility provider.

4. Allocation shall be made on the basis of rented spaces.

D. A landlord that is also a mobile home park as defined in section 33-1409 shall comply with subsection A, paragraph 1 and subsection B of this section.

E. The landlord shall provide a statement of proposed interruption of utility service to the tenants within a reasonable time, except in the case of an interruption caused by an emergency. An emergency does not include any failure or refusal by the landlord to fulfill the duties and obligations to maintain fit premises. A statement of proposed interruption of utility service may be provided by posting an announcement of the period of the interruption in a conspicuous place on the premises where a recreational vehicle space is located or by individual delivery to each tenant.

F. For the purpose of regulating recreational vehicle parks as public or consecutive water systems, the state shall not adopt rules pursuant to title 49, chapter 2, article 9 that are more stringent than authorized by the federal government. Submetering solely to determine the charges for individual water use by park tenants for the purpose of water conservation, without other evidence indicating a transaction subject to regulation under title 49, chapter 2, article 9, shall not be used as a basis for treating any recreational vehicle park as a public or consecutive water system.

G. A landlord may charge separately for removal of waste, garbage, rubbish, refuse and trash and for sewer services. Any charges for removal or sewer services shall not exceed the prevailing single family or residential charge, fee or rate for these services levied by the political subdivision or provider.

H. A landlord who determines, on the landlord's own or as a result of a tenant objection, that the landlord has overcharged tenants shall refund the overcharged amount to the tenants who were overcharged and who reside in the recreational vehicle park at the time the overcharge is determined. The refund shall be made through a credit toward future utility charges or a refund and shall be provided within sixty days.

I. If a tenant believes that a landlord is not in compliance with this section, the tenant shall provide written notice to the landlord regarding the alleged violation of this section. If the dispute is not resolved within thirty days after the notice is received by the landlord, the tenant may file a civil complaint in justice court to enforce this section. In an action pursuant to this subsection, the court shall award the prevailing party court costs and reasonable attorney fees.