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Calcimator

Chlorine Dosing Calculator

Calculate chlorine dose and feed rate for water disinfection, including CT compliance for pathogen inactivation.

Inputs

MGD
mg/L
mg/L
minutes
°C

Results

Total Chlorine Dose

2 mg/L

Chlorine Feed Rate

41.7 lbs/day

CT ComplianceNon-Compliant — Increase dose or contact time
CT Achieved15 mg·min/L
CT Required75 mg·min/L
Log Inactivation0.4-log
NaOCl (12.5%) Feed33.4 gal/day
Cal-Hypo (65%) Feed64.2 lbs/day
Annual NaOCl Cost$42,617
Annual Gas Cl₂ Cost$6,088
DBP Formation RiskLow
How to Use This Calculator
  1. Enter Plant Flow Rate (MGD) and the Target Chlorine Residual (mg/L) required at the distribution system entry point.
  2. Input Chlorine Demand (mg/L) — this is typically determined by bench testing or historical operational data.
  3. Set Contact Time (minutes) for your clearwell or contact basin and select the Target Pathogen for CT table lookup.
  4. Enter Water Temperature (°C) — CT requirements increase significantly in colder water.
  5. Review Total Chlorine Dose and Chlorine Feed Rate (lbs/day) to set chemical feed pump outputs.
  6. Check CT Compliance status to verify your disinfection practice meets SWTR regulatory requirements.
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