For purposes of the Reverse Osmosis System Tax Credit Act:

(1) Department means the Department of Revenue;

(2) Hazard Index means a calculation used to evaluate potential health risks from exposure to one or more of the four listed chemicals using their individual health safety limits as established by the United States Environmental Protection Agency. The Hazard Index is the sum of the ratios of actual chemical concentrations to the respective health safety limit;

(3) Reverse osmosis system means a water filtration system that uses a semi-permeable membrane to remove impurities from water; and

(4) Taxpayer means any individual subject to the income tax imposed by the Nebraska Revenue Act of 1967.