Maximum contaminant levels for turbidity.
The maximum contaminant levels for turbidity are applicable to both community water systems and non-community water systems using surface water sources in whole or in part. The maximum contaminant levels for turbidity in drinking water, measured at a representative entry point(s) to the distribution system, are:
At 54 FR 27527, June 29, 1989, § 141.13
was amended by adding introductory text, effective December 31, 1990. However, introductory text already exists. The added text follows.
The requirements in this section apply to unfiltered systems until December 30, 1991, unless the State has determined prior to that date, in writing pursuant to § 1412(b)(7)(C)(iii), that filtration is required. The requirements in this section apply to filtered systems until June 29, 1993. The requirements in this section apply to unfiltered systems that the State has determined, in writing pursuant to § 1412(b)(7)(C)(iii), must install filtration, until June 29, 1993, or until filtration is installed, whichever is later.
One turbidity unit (TU), as determined by a monthly average pursuant to § 141.22, except that five or fewer turbidity units may be allowed if the supplier of water can demonstrate to the State that the higher turbidity does not do any of the following:
Interfere with disinfection;
Prevent maintenance of an effective disinfectant agent throughout the distribution system; or
Interfere with microbiological determinations.
Five turbidity units based on an average for two consecutive days pursuant to § 141.22.
[40 FR 59570, Dec. 24, 1975]