What this tool does
Shows the arithmetic behind CT and, when the user supplies a target, reports only a simple mathematical margin.
When to use it
Use with a measured residual at the correct location and a baffling or effective-volume factor obtained from design information or applicable guidance.
Inputs and supported units
Each labelled field explains the quantity it expects. Unit-system changes convert existing numeric entries once and keep calculations on a single SI internal basis. Supported shared units include L/min and GPM, metres and feet, kPa and psi, millimetres and inches, kW and hp, and °C and °F as relevant.
Calculation or decision method
How to interpret the result
Read the primary result with the supporting breakdown and warning. A plausible number is not evidence that every input, operating case or design constraint has been included.
Worked example
A 5,000 L contact volume at 100 L/min has 50 minutes nominal detention. With 0.7 baffling and 0.5 mg/L measured residual, effective time is 35 minutes and CT is 17.5 mg·min/L.
Assumptions
The entered water test, flow, product concentration and manufacturer values represent the same source, use and operating condition.
Limitations
The result is a transparent preliminary calculation or decision screen. It does not establish contaminant removal, potable safety, product certification, regulatory compliance or an approved treatment design.
Sources
- U.S. EPA — Disinfection Profiling and Benchmarking Technical Guidance
- World Health Organization — Guidelines for Drinking-water Quality