Rules & Regulations of the State of Tennessee
Title 0400 - Environment and Conservation
Subtitle 0400-45 - Water Resources (Water Supply)
Chapter 0400-45-01 - Public Water Systems
Section 0400-45-01-.08 - TURBIDITY SAMPLING AND ANALYTICAL REQUIREMENTS

Universal Citation: TN Comp Rules and Regs 0400-45-01-.08

Current through December 26, 2024

(1) Ground water sampling - Samples shall be taken by suppliers of water that serve more than 50 connections or that have been directed to conduct monitoring under paragraph (11) of Rule 0400-45-01-.05 for both community water systems and non-community water system at a representative entry point(s) to the water distribution system at least once per day for the purpose of making turbidity measurements to determine compliance with paragraph (3) of Rule 0400-45-01-.06. Public water systems using water from a source not under the direct influence of surface water are not required to monitor turbidity unless directed to do so under the provisions of paragraph (11) of Rule 0400-45-01-.05.

(2) Turbidity measurements of surface water and ground water under the direct influence that employs filtration - The minimum sampling requirements for systems using filtration treatment shall be as follows:

(a) Turbidity measurements must be performed on representative samples of the system's filtered water every four hours, (or more frequently, as authorized by the rules) that the system serves water to the public. A public water system may substitute continuous turbidity monitoring for grab samples if approved in writing by the Department. For systems serving 500 or fewer persons per day, the Department may allow the sampling frequency to be reduced to once per day if it determines that less frequent monitoring is sufficient to indicate effective filtration performance. Systems filtering surface water and ground water under the direct influence of surface water shall comply with the treatment technique standards found in paragraph (4) of Rule 0400-45-01-.31.

(3) Ground water systems under the direct influence of surface water and do not filter and have qualified to avoid filtration - The minimum sampling requirements for ground water systems under the direct influence of surface water and not employing filtration shall be as follows:

(a) Turbidity measurements must be performed on representative grab samples of source water immediately prior to the first or only point of disinfectant application every four hours (or more frequently, as authorized by the rules) that the system serves water to the public. A public water system may substitute continuous turbidity monitoring for grab sample monitoring if it validates the continuous measurement for accuracy on a regular basis using a protocol approved by the Department. Turbidity must comply with the limits specified in part (2)(a)2 of Rule 0400-45-01-.31.

(4) Reporting

(a) Ground water systems - All community water systems using a ground water source with turbidity removal facilities and not designated as ground water under the direct influence of surface water shall be required, if the results of a turbidity analysis indicate that the maximum allowable limit has been exceeded, to confirm by resampling as soon as practicable and preferably within one (1) hour. If the repeat sample confirms that the maximum allowable limit has been exceeded, the supplier of water shall report to the Department within forty-eight (48) hours. The repeat sample shall be the sample used for the purpose of calculating the monthly average. If the monthly average of the daily samples exceeds the maximum allowable limit, or if the average of two samples taken on consecutive days exceeds two (2) NTU, the supplier of water shall report to the Department and notify the public as directed in Rules 0400-45-01-.18 and 0400-45-01-.19. All non-community water systems using ground water formations, other than approved sand and gravel formations, may be required to monitor turbidity if the Department finds a system cannot meet the microbiological standard, the turbidity limit is exceeded, or if other health related problems exist.

(b) Surface water systems and ground water systems under the direct influence of surface water -Turbidity measurements must be reported within 10 days after the end of each month the system serves water to the public. Information that must be reported includes but is not limited to:
1. The total number of filtered water turbidity measurements taken during the month.

2. The number and percentage of filtered water turbidity measurements taken during the month which are less than or equal to the applicable limits specified in paragraph (4) of Rule 0400-45-01-.31.

3. The date and value of any turbidity measurements taken during the month which exceed 5 NTU.

(c) Ground water systems under the direct influence of surface water that have qualified to avoid filtration - Information that must be reported includes but is not limited to:
1. The maximum turbidity level measured during the month, the date(s) of occurrence for any measurement(s) which exceeded 5 NTU, and the date(s) the occurrence(s) was reported to the Department.

2. For the first 12 months of recordkeeping, the dates and cumulative number of events during which the turbidity exceeded 5 NTU, and after one year of recordkeeping for turbidity measurements, the dates and cumulative number of events during which the turbidity exceeded 5 NTU in the previous 12 months the system served water to the public.

3. For the first 120 months of recordkeeping, the dates and cumulative number of events during which the turbidity exceeded 5 NTU, and after 10 years of recordkeeping for turbidity measurements, the dates and cumulative number of events during which the turbidity exceeded 5 NTU in the previous 120 months the system served water to the public.

(d) Ground water systems under the direct influence of surface water that has been directed to install filtration but has not yet done so shall monitor as specified in subparagraph (a) of this paragraph.

Authority: T.C.A. §§ 68-221-701 et seq. and 4-5-201 et seq.

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