Course Glossary

This shows the specialized terms used in EarthWise Academy. This section contains all the definitions used in the various course glossaries used by each course.

Browse the glossary using this index

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Entries starting with: D

Design Basis Threat

Design Basis Threat (DBT)

Description of a specific adversary and mode of attack that has a degree of likelihood of occurring.

  • (SEC01) Securing Drinking Water and Wastewater Treatment Facilities 2954


A condition in which the electrical charge of particles has been neutralized.

  • (COA01) Coagulation – Part 1: The Chemistry of Coagulation (1248)
  • (DBP43) Jar Testing for Process Control of Conventional Filtration: Part 1 (2019)

Detected Contaminant

Any contaminant detected at or above its detection limit.

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

Detection Limit

The amount of a substance with that EPA has determined to be the minimum concentration that can be measured and reported with 99% confidence that the true value is greater than zero.

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

Detention Time

The theoretical time that a parcel of water or other liquid spends in a particular treatment unit or reservoir.

  • (COA01) Coagulation – Part 1: The Chemistry of Coagulation (1248)

Diatomaceous Earth

A fine material made up mostly of the skeletal remains of single cell, microscopic algae with a rigid, box-like internal structure consisting mainly of silica.

  • (DBP40) Enhanced Coagulation – Basics (1280)

Digester Capacity

The total volume in gallons that a digester(s) can hold, or the volume used during the monitoring period, if not operating at full capacity.

  • (BIO10) Estimating Sludge Volume (2343)

Discharge Monitoring Report

Discharge Monitoring Report (DMR)


Substances that are added for the purpose of killing or inactivating the pathogenic (disease-causing) bacteria found in water.

Chlorine, Chloramines, & Chlorine Dioxide are disinfectants.

  • (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)

Disinfection Byproducts Precursors

Organic substances that combine with disinfectants to form potentially carcinogenic compounds such as HAA5’s and TTHM’s.

  • (DBP43) Jar Testing for Process Control of Conventional Filtration: Part 1 (2019)

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