(1) "Contribution in aid of construction" means any money, services, or property received by a water or sewer utility to fund capital investments at no cost to the company with no obligation to repay.

(2) "Customer" means any individual or entity supplied with water or sewer service by means of a water or sewer line that connects a single building or living unit to the utility's water or sewer system. For purposes of these rules, each single building or living unit connected to the utility's system is one customer.

(3) "Operating ratio" means the ratio of a utility's operating expenses to operating revenues. For purposes of ARM 38.5.2529, a small water or sewer utility's operating ratio will be determined based on the expense and revenue information required to be submitted by the utility on the department's operating ratio methodology form referred to in ARM 38.5.2529(2).

(4) "Small water or sewer utility" means a water or sewer utility subject to the commission's jurisdiction that serves fewer than 500 customers.