NR 809.31(3)(b)3.3. The department has substantial grounds to believe that a total coliform-positive result is due to a circumstance or condition which does not reflect water quality in the distribution system. In this case, the water supplier shall still collect all repeat samples required, and shall use them to determine whether a coliform treatment technique trigger in s. NR 809.313 has been exceeded. To invalidate a total coliform-positive sample under this paragraph, the decision with the rationale for the decision shall be documented in writing, approved by a qualified department official and available to the public for inspection. The document shall state the specific cause of the total coliform-positive sample, and what action the water supplier has taken or will take, to correct this problem. The department may not invalidate a total coliform-positive sample solely on the grounds that all repeat samples are total coliform-negative.

NR 809.31(3)(c)(c) A laboratory shall invalidate a total coliform sample if the sample produces a turbid culture in the absence of gas production using an analytical method where gas formation is examined for, example, the Multiple Tube Fermentation Technique, produces a turbid culture in the absence of an acid reaction in the Presence-Absence Coliform Test, or exhibits confluent growth or produces colonies too numerous to count with an analytical method using a membrane filter, for example, Membrane Filter Technique, except that a laboratory shall not invalidate a total coliform sample if total coliforms are detected. If a laboratory invalidates a sample because of such interference, the water supplier shall collect another sample from the same location as the original sample within 24 hours of being notified of the interference problem, and have it analyzed for the presence of total coliforms. The water supplier shall continue to re-sample every 24 hours and have the samples analyzed until a valid result is obtained. The department may waive the 24 hour time limit on a case-by-case basis. Alternatively, the department may implement criteria for waiving the 24-hour sampling time limit to use in lieu of case-by-case extensions.

NR 809.31(4)(a)(a) If any routine or repeat sample is total coliform-positive, the water supplier shall analyze that total coliform-positive culture medium to determine if E. coli are present. If E. coli are present, the water supplier shall notify the department by the end of the day when the water supplier is notified of the test result, unless the water supplier is notified of the result after normal department business hours, in which case the water supplier shall notify the department before the end of the next business day.

NR 809.31(4)(b)(b) The department may allow a water supplier for a public water system, on a case-by-case basis, to forgo E. coli testing on a total coliform-positive sample if that water supplier assumes that the total coliform-positive sample is E. coli positive. Accordingly, the water supplier shall notify the department as specified in par. (a) and the provisions of s. NR 809.30 (2) apply.

NR 809.31(5)(5) Groundwater system raw water sampling. In addition to sampling from the distribution system, each water supplier for a public water system providing disinfection shall obtain at least one sample every 3 months from each well prior to the point of treatment. For public water systems which have more than one well in the same location and utilizing the same aquifer, the supplier of water may sample only one of the wells each time on an alternating basis. If a well has a high potential for contamination, the department may, in individual cases, require more frequent sampling.

NR 809.31(6)(6) Surface water system raw water sampling. At surface water facilities, the microbiological quality of the source water shall be monitored sufficiently to maintain quality control of the treatment process. Water suppliers shall establish a schedule for each plant, subject to review and modification by the department.

NR 809.31 NoteNote: Generally, enumeration methods such as membrane filter, numeric enzyme substrate, or 5 tube fermentation tests and heterotrophic plate counts of the raw, settled and finished water on an established schedule will be necessary to meet this requirement.

NR 809.31(7)(7) Heterotrophic plate counts. At all waterworks which have a potential for high total bacteria levels because of the water quality, the method of treatment, chemical addition or other cause, the department may require heterotrophic plate counts pursuant to an established schedule. Analyses shall be conducted in accordance with the analytical requirements in s. NR 809.311 (1), Table F.

NR 809.31(9)(a)(a) Failure to take every required routine or additional routine sample in a compliance period is a monitoring violation.

NR 809.31(9)(b)(b) Failure to analyze for E. coli following a total coliform-positive routine sample is a monitoring violation.

NR 809.31(10)(a)(a) Failure to submit a monitoring report or completed assessment form after a water supplier properly conducts monitoring or assessment in a timely manner is a reporting violation.

NR 809.31(10)(b)(b) Failure to notify the department following an E. coli-positive sample as required by sub. (4) in a timely manner is a reporting violation.

NR 809.31(10)(c)(c) Failure to submit certification of completion of department-approved start-up procedure by a seasonal system is a reporting violation.

NR 809.31 HistoryHistory: CR 09-073: cr. Register November 2010 No. 659, eff. 12-1-10; CR 15-049: am. (1) (title), (a), cr. (1) (ag), (ar), renum. (1) (b) 1. to (b) and am., r. (1) (b) 2., renum. (1) (c) to (d) 4. and am., renum. (1) (d) to (c) and am., cr. (1) (de), (dg), (dr), am. (1) (e), cr. (1) (eg), (er), am. (1) (f), (g), (2) (a), renum. (2) (b) to (b) (intro.) and am., cr. (2) (b) 1. to 3., am. (2) (c) to (e), r. and recr. (2) (f) (intro.), am. (2) (f) 1., 2., cr. (2) (f) 3., am. (2) (h), cr. (2m), am. (3) (b) 2., 3., (c), (4) to (6), cr. (9), (10) Register March 2016 No. 723, eff. 4-1-16; corrections in (1) (d) 2. (intro.), (2) (a) (intro.), (b) (intro.), (f) (intro.), (2m) (d) (intro.), (e), (3) (b) 2. made under s. 35.17, Stats., Register March 2016 No. 723; correction in (1) (ag), (ar) made under s. 13.92 (4) (b) 7., Stats., Register July 2022 No. 799.

NR 809.311(3)(a)(a) Sample collection for microbiological contaminants under s. NR 809.30 shall be conducted using the sample preservation, containers and maximum holding time procedures specified in par. (b).

NR 809.311(3)(b)(b) Sample preservation requirements and holding times for microbiological samples are specified in subds. 1. and 2. In all cases, samples shall be analyzed as soon after collection as possible.

NR 809.311(3)(b)1.1. Total Coliform and E. coli samples are not required to be preserved by cooling to 10° C, however it is encouraged during transit. Sodium thiosulfate shall be added to the sample container prior to adding water containing chlorine and the holding time shall be 30 hours.