part_subject: "NATIONAL PRIMARY DRINKING WATER REGULATIONS"
subpart_code: "T"
subpart_subject: "Enhanced Filtration and Disinfection—Systems Serving Fewer Than 10,000 People"
section_number: "141.551"
section_subject: "What strengthened combined filter effluent turbidity limits must my system meet?"
cfr_reference: "40 CFR 141.551"
title_name: "Title 40"
title_subject: "Protection of Environment"
parts_covered: "Parts 136 to 149"
revised_date: "Revised as of July 1, 2019"
publication_date: "As of July 1, 2019"
contains_description: "Containing a codification of documents of general applicability and future effect"
publication_info: "Published by the Office of the Federal Register National Archives and Records Administration as a Special Edition of the Federal Register"
---
Your system must meet two strengthened combined filter effluent turbidity limits.
(a)The first combined filter effluent turbidity limit is a “95th percentile” turbidity limit that your system must meet in at least 95 percent of the turbidity measurements taken each month. Measurements must continue to be taken as described in § 141.74(a) and (c). Monthly reporting must be completed according to § 141.570. The following table describes the required limits for specific filtration technologies.
(b)The second combined filter effluent turbidity limit is a “maximum” turbidity limit which your system may at no time exceed during the month. Measurements must continue to be taken as described in § 141.74(a) and (c). Monthly reporting must be completed according to § 141.570. The following table describes the required limits for specific filtration technologies.