What engineering standard and governing formula does the Chlorine Contact Time (CT) & Disinfection Log Credit use?

The Chlorine Contact Time (CT) & Disinfection Log Credit utilizes verified formulations conforming to EPA Surface Water Treatment Rule (SWTR) Guidance Manual. It computes results using peer-reviewed equations with transparent mathematical step-by-step substitution for verification.

Can I export official calculation sheets for PE (Professional Engineer) submittals?

Yes. Click the 'Generate PE Submittal PDF' button inside the calculator to export a clean, timestamped engineering calculation sheet with inputs, intermediate variables, unit conversions, and signature review blocks.

Does the Chlorine Contact Time (CT) & Disinfection Log Credit support dual Imperial and Metric units?

Yes, you can toggle instantaneously between US Customary (Imperial) and SI Metric units with zero calculation drift or rounding artifacts.

What input variables are required to run the Chlorine Contact Time (CT) & Disinfection Log Credit?

The required design inputs are: Free Chlorine Residual (C) (C), Contact Basin Volume (V) (V), Peak Hourly Flow Rate (Q) (Q_peak), Basin Baffling Factor (T10 / T_avg) (θ_baffle), Water Temperature (T), Water pH Level (pH).

EPA Surface Water Treatment Rule (SWTR) Guidance Manual

Chlorine Contact Time (CT) & Disinfection Log Credit

EPA SWTR disinfection CT value, T10 baffle factor, and pathogen log reduction

Engineering Process Reference: Chlorine Contact Time (CT) & Disinfection Log Credit Calculator governing plant layout conforming to EPA Surface Water Treatment Rule (SWTR) Guidance Manual.

1. Engineering Principles & Mathematical Formulation

Calculates T10 contact time, actual CT achieved (mg-min/L), and required disinfection log inactivation credits for Giardia and Virus based on residual chlorine, pH, temperature, and basin baffle efficiency.

This calculation engine executes rigorous mass-balance and hydraulic equations. Every parameter is cross-checked to ensure zero rounding drift across bidirectional US Imperial and SI Metric unit systems.

2. Governing Standards & Authoritative Citations

"Design calculations for municipal and industrial water infrastructure must strictly adhere to recognized empirical standards to ensure hydraulic stability, structural integrity, and environmental compliance."
— EPA Surface Water Treatment Rule (SWTR) Guidance Manual, American Water Works Association (AWWA) & U.S. Environmental Protection Agency (EPA Manual 832-B-99-002)

Primary benchmark citations include Crane Technical Paper No. 410, ASME Section VIII, and Metcalf & Eddy Wastewater Engineering.

3. Required Input Parameters & Variables

Symbol: C

Free Chlorine Residual (C)

Default: 1.8 (mg/L)

Symbol: V

Contact Basin Volume (V)

Default: 250000 (gallons)

Symbol: Q_peak

Peak Hourly Flow Rate (Q)

Default: 5 (MGD)

Symbol: θ_baffle

Basin Baffling Factor (T10 / T_avg)

Default: 0.5 (ratio)

Symbol: T

Water Temperature

Default: 50 (°F)

Symbol: pH

Water pH Level

Default: 7.5 (pH)

4. Professional Engineer (PE) Submittal Workflow

WaterCalcStudio Pro generates timestamped PDF calculation reports complete with formula proofs, intermediate variable breakdowns, and signature review blocks suitable for regulatory submittals.