Pa. DEP Operator eLearning Center

1. MCL - Maximum Contaminant Level
   The maximum permissible level of a contaminant in water that is delivered to a user of a public water system.
   • (CCR01)Consumer Confidence Report (CCR) Overview (2338)
   • (DBP01) DBP Rule – Overview (1282)
   • (DBP02) DBP Rule Monitoring and Reporting – Job Aids (1283)
   • (DBP10) DBP Rule Monitoring and Reporting for Chlorine⁄Chloramines (1284)
   • (DBP13) DBP Rule Monitoring and Reporting for TTHM⁄HAA5 (1285)
   • (DBP14) DBP Rule Violations for Pa. PWSs using Chorine⁄Chloramines (1825)
   • (DBP15) DBP Rule – Maintaining Compliance for Pa. PWSs using Chlorine/Chloramines (1570)
   • (DBP20) DBP Rule Monitoring and Reporting for PWSs Using Chlorine Dioxide (1278)
   • (DBP30) DBP Rule Monitoring and Reporting Requirements for PWSs Using Ozone (1279)
   • (DBP40) Enhanced Coagulation – Basics (1280)
   • (LCR11) LCR – Initial Planning, Monitoring and Reporting (1488)
   • (PNR01) Public Notification – An Introduction for NCWSs (2332)
   • (RAD01) Radionuclide Rule – Initial Monitoring and Reporting (1503)
2. The highest amount of a contaminant that the EPA allows which helps ensure that drinking water does not pose either a short-term or long-term health risk. Unless otherwise specified, MCLs are defined in milligrams per liter (parts per million).
   • (LCR10) Lead and Copper Rule — Basics (1423)
   • (TCR01) Total Coliform Rule – Overview (1424)
   • (TCR02) Total Coliform Rule – Monitoring And Reporting Requirements (1425)
   • (TCR03) Total Coliform Rule – Maintaining Compliance (1426)

MCLG – Maximum Contaminant Level Goal

The level of a contaminant in drinking water below which there is no known or expected risk to health. MCLGs allow for a margin of safety.

• (CCR01)Consumer Confidence Report (CCR) Overview (2338)

Microbial/Disinfectants and Disinfection Byproduct – (M/DBP)

• (DBP02) DBP Rule Monitoring and Reporting – Job Aids (1283)
• (DBP10) DBP Rule Monitoring and Reporting for Chlorine⁄Chloramines (1284)
• (DBP13) DBP Rule Monitoring and Reporting for TTHM⁄HAA5 (1285)

1. Tiny masses of non-settleable microorganisms and particles that come together to form progressively larger, heavier particles.
   • (COA01) Coagulation – Part 1: The Chemistry of Coagulation (1248)
2. Very small (usually visible to the human eye) masses of non-settleable microorganisms and particles. These are beginning stages of flocs that come together to form progressively larger, heavier particles.
   • (COA02) Coagulation — Part 2: Coagulation Chemicals (1249))

MLSS – Mixed Liquor Suspended Solids

The concentration of suspended solids (both organic and inorganic) in the mixed liquor of an aeration tank. MLSS is used as a measure of the concentration of microorganisms present.

Any violation incurred for failing to monitor and/or report for a regulated parameter specified by the Pa. DEP.

• (PNR01) Public Notification – An Introduction for NCWSs (2332)
• (PNR11) Public Notification – Violations and Tiers for NCWSs (2333)

The time frame, generally in months, quarters, or years, during which water samples must be collected and tested in accordance with Pa Safe Drinking Water Regulations to determine compliance with applicable MCLs, MRDLs, or treatment techniques

• (TCR01) Total Coliform Rule – Overview (1424)
• (TCR02) Total Coliform Rule – Monitoring And Reporting Requirements (1425)
• (TCR03) Total Coliform Rule – Maintaining Compliance (1426)

MRDLG – Maximum Residual Disinfectant Level Goal

The unenforceable maximum level of disinfectant added for water treatment for which there is no known risk to human health.

• (CCR01)Consumer Confidence Report (CCR) Overview (2338)

This refers to the condition where a PWS serves many individual buildings (connections), i.e., homes or businesses that use public water.

• (TCR01) Total Coliform Rule – Overview (1424)
• (TCR02) Total Coliform Rule – Monitoring And Reporting Requirements (1425)
• (TCR03) Total Coliform Rule – Maintaining Compliance (1426)

1. Buildings that are not used by a LSL and do not contain lead pipes or copper pipes with lead solder
2. Building containing copper plumbing materials (lead-free solder) installed after January 6, 1991

• (LCR13) LCR Planning Tools for NTNCWS (2537)