Authority: IC 13-14-8; IC 13-14-9; IC 13-15-1-2; IC 13-15-2-1; IC 13-18-3-1; IC 13-18-4-1

Affected: IC 13-11-2; IC 13-13-5-1; IC 13-18

Sec. 3. (a) Unless otherwise indicated, the definitions in the following apply to this article:

(1) IC 13-11-2.

(2) This rule.

(3) 40 CFR 141.2*.

(b) In addition to subsection (a), the following definitions apply to this article:

(1) "Adjustment program" means the addition of fluoride to drinking water by a public water system for the prevention of dental cavities.

(2) "Contaminant" means any of the following substances or matter introduced or found in drinking water:

(A) Biological.

(B) Chemical.

(C) Physical.

(D) Radiological.

(3) "Service interruption" means a disturbance in the provision of water to a customer affecting quality or quantity.

(4) "Surface water" means all water that is open to the atmosphere and subject to surface runoff.

(5) "Undetectable disinfectant residual" means a disinfectant residual level that is less than:

(A) two-tenths (0.2) milligram per liter measured as free chlorine;

(B) five-tenths (0.5) milligram per liter measured as combined chlorine (chloramines); or

(C) one-tenth (0.1) milligram per liter measured as chlorine dioxide.

The commissioner may require a system to demonstrate the level of chloramines present when measured as combined chlorines under clause (B).

(6) "Water loss" means the following:

(A) A calculation based on the difference between the following:

(i) The amount of water purchased.

(ii) The annual volume of water metered, including unmetered water taken by the following:

(AA) Customers authorized to take water.

(BB) The water system.

(CC) Others authorized to take water.

(B) Inclusions of the following:

(i) Unauthorized consumption.

(ii) Metering inaccuracies.

(iii) Data handling errors.

(iv) Leaks, breaks, and overflows on the following:

(AA) Mains.

(BB) Service reservoirs.

(CC) Service connections up to the point of customer metering.

*These documents are incorporated by reference. Copies may be obtained from the Government Publishing Office, www.gpo.gov, or are available for review at the Indiana Department of Environmental Management, Office of Legal Counsel, Indiana Government Center North, 100 North Senate Avenue, Thirteenth Floor, Indianapolis, IN 46204.

(Water Pollution Control Division; 327 IAC 8-2.7-3; filed Nov 24, 2025, 9:07 a.m.: 20251224-IR-327240428FRA)