Chlorine Dioxide Dose Calculator

Chlorine dioxide is a strong oxidant with tight regulatory limits. Enter flow and dose to get lb/day — and a reminder of the 0.8 mg/L MRDL and the 1.0 mg/L chlorite MCL.

Water flow

Flow unit

ClO₂ dose (mg/L)Doses above 0.8 mg/L risk exceeding the MRDL in the distribution system.

MRDL 0.8 mg/L as ClO₂ (40 CFR 141.65); chlorite MCL 1.0 mg/L (40 CFR 141.64).

Chlorine Dioxide Feed

Item	Value

How the calculation works

Formulas
Flow (MGD) = gpm × 1,440 ÷ 1,000,000
ClO₂ (lb/day) = 8.34 × flow (MGD) × dose (mg/L)

Regulatory limit (Stage 1 DBPR)	Value
Chlorine dioxide MRDL (40 CFR 141.65)	0.8 mg/L
Chlorite MCL (40 CFR 141.64)	1.0 mg/L

Notes & limitations

Under the Stage 1 Disinfectants and Disinfection Byproducts Rule, chlorine dioxide has a maximum residual disinfectant level (MRDL) of 0.8 mg/L, and its breakdown product chlorite has an MCL of 1.0 mg/L. Roughly half or more of the dosed ClO₂ converts to chlorite, so chlorite — not just ClO₂ residual — usually sets the practical dose ceiling.

Monitor chlorite at the entry point as required; an MCL violation triggers public notification and treatment-technique follow-up per state rules.
Chlorine dioxide must be generated on site (commonly sodium chlorite plus chlorine or acid). Never exceed the generator manufacturer’s feed ratios — off-ratio generation wastes chemical and can form unwanted byproducts.
Dose here is the applied dose at the injection point, not the distribution system residual. Residual decays with demand, time, and temperature.
This tool is for operational feed-rate setting. Confirm against compliance sampling results and plant SOPs.

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