(a) The supplier of water may request, and the department may grant, one or more variances from an MCL contained in sections 5-1.51 and 5-1.52 tables 1, 3, 5 and 7 of this Subpart to any public water system based on a finding that:

1. (1) because of characteristics of the raw water sources which are reasonably available to it, the public water system cannot meet the requirements respecting such MCL despite application of the best available technology, treatment techniques or other means which are generally available, taking costs into consideration; and
2. (2) the granting of a variance will not result in an unreasonable risk to health.

(b) At the time of the granting of the variance, the department shall prescribe, and the supplier of water shall follow, a schedule for:

1. (1) compliance, including increments of progress, to meet each MCL covered by the variance; and
2. (2) implementation of such control measures as the department may require.