StacksVerified U.S. regulatory reference

40 CFR §141.551

Verified against eCFR.gov as of June 20, 2026View official text on eCFR.gov ↗
Your system must meet two strengthened combined filter effluent turbidity limits.
  1. (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.
  2. (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.