Glossary
Water and wastewater operator glossary
Plain-language definitions of the terms that show up most on the Texas Class D exams. No jargon for its own sake, just what each term means and why it matters at the plant.
Drinking water
- Potable water
- Water that is safe to drink.
- Groundwater
- Water pumped from underground through wells.
- Surface water
- Water drawn from lakes, rivers, or reservoirs.
- Distribution system
- The pipes, pumps, and storage tanks that carry treated water from the plant to customers.
- Coliform bacteria
- Indicator organisms tested for in water. Finding them signals that contamination may have reached the system.
- Turbidity
- A measure of how cloudy water is from suspended particles. High turbidity can shield organisms from disinfection.
Disinfection and chlorine
- Disinfection
- Killing or inactivating harmful organisms in water, most often with chlorine.
- Chlorine dose
- The total amount of chlorine added to the water, measured in mg/L.
- Chlorine demand
- The chlorine used up by reactions in the water before any is left over.
- Chlorine residual
- The chlorine left in the water after demand is met, which keeps protecting it downstream. Dose equals demand plus residual.
Wastewater
- Influent
- The wastewater flowing into a treatment plant.
- Effluent
- The treated water flowing out of a plant.
- Collection system
- The sewers and lift stations that carry wastewater from homes and businesses to the plant.
- Activated sludge
- A treatment process that uses microorganisms and added air to break down waste in the water.
- Clarifier
- A tank where solids settle out of the water so the cleaner water above can move on.
- Biosolids
- The treated solids removed from wastewater, which are sometimes reused on land under strict rules.
Units and measures
- MGD
- Million gallons per day, a common way to report the flow through a plant.
- GPM
- Gallons per minute.
- GPD
- Gallons per day.
- Cubic foot
- A volume one foot on each side. One cubic foot of water holds 7.48 gallons.