Free water operator tool
Chlorine dosage calculator
Chlorine dose, demand, and residual follow one relationship: dose equals demand plus residual. Enter the two you know and this tool finds the third in mg/L, showing every step. It is the disinfection math on the Texas Class D water exam, and the same math you use at the plant.
How the tool works
Chlorine you add is either used up (the demand) or left over (the residual). So the dose you feed is demand plus the residual you want to hold: dose equals demand plus residual. Rearranged, the residual you will get is dose minus demand. Every value in the worked solution traces to a number you entered, so there is nothing to take on faith.