(1) Existing water supply systems within a proposed subdivision must meet all requirements of this chapter or, if previously approved by the reviewing authority, the rules in effect at the time of approval. The department may grant a waiver, pursuant to ARM 17.36.601, from the well construction requirements of ARM 17.36.333 if the applicant provides adequate evidence that compliance with such requirements is not necessary to ensure an adequate water supply.

(2) The applicant shall submit information to allow the reviewing authority to review the quality, quantity, and dependability of the existing system.

(a) The applicant shall submit, for each existing water supply source, water quality analyses for nitrate (as nitrogen) and specific conductance. If an existing well is currently being used as a potable water supply within a proposed subdivision, a total coliform analysis must also be conducted. The nitrate and specific conductance sample may not be older than one year prior to the date of the application. The coliform sample may not be older than six months prior to the date of application. If an existing well is not currently used as a potable water supply but will be converted to a potable water supply, a total coliform analysis must be conducted when it is put into use. The analysis must be performed by a laboratory certified by the department of public health and human services for analyses of water samples for public water systems. The reviewing authority may not approve the use of an existing system if there is evidence that, after appropriate treatment, the concentration of any ground water constituent exceeds the human health standards in department Circular DEQ-7, or the maximum contaminant levels established in ARM Title 17, chapter 38, subchapter 2.

(b) To characterize the water supply, the applicant must show, through a well log or other means, the depth to static water in the well and the total well depth.