Chlorine Dose For Water Calculator

Work out chlorine dose for water instantly with clear inputs, formula shown and shareable results.

About Chlorine Dose For Water Calculator

Chlorine mass required is flow times dose: 1 mg/L on 1000 cubic metres is 1 kilogram. Dividing by the product's available chlorine gives the weight of bleaching powder or hypochlorite to dose. The residual is the dose less the chlorine demand consumed by organics, ammonia, iron and manganese.

Formulas

Chlorine dose

Chlorine (kg/day) = flow (m3/day) x dose (mg/L) / 1000

Residual

Free residual = dose - chlorine demand

Worked example

With the default values below, Chlorine Dose For Water Calculator returns Product Required of 32.692. Change any input above and every figure here is recalculated in your browser.

Inputs used

Flow Rateminimum 0 m3/day: 8,500 m3/day
Target Chlorine Doseminimum 0 mg/L: 2.5 mg/L
Available Chlorine In Productaccepts 0–100 %: 65 %
Chlorine Demand Of The Waterminimum 0 mg/L: 1.8 mg/L

Results

Product Required: 32.692
Available Chlorine Required: 21.2500
Expected Free Residual: 0.700
Dose For 0.5 mg/L Residual: 2.300

Step by step

1Values used
2Chlorine dose
3Residual
4Product Required= 32.692
5Available Chlorine Required= 21.2500
6Expected Free Residual= 0.700
7Dose For 0.5 mg/L Residual= 2.300

Assumptions and limits

The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
Chlorination is a critical public health barrier. Doses must be verified by residual measurement, and chlorine gas and concentrated hypochlorite are hazardous chemicals requiring specific safety controls.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Chlorination is a critical public health barrier. Doses must be verified by residual measurement, and chlorine gas and concentrated hypochlorite are hazardous chemicals requiring specific safety controls.

Frequently Asked Questions

What residual should be maintained?

Typically 0.2-0.5 mg/L free chlorine at the far end of the distribution network, with 0.5-1.0 mg/L leaving the works to allow for decay. Local standards vary and take precedence.

What is breakpoint chlorination?

Where ammonia is present, chlorine first forms chloramines and free residual only appears once enough chlorine has been added to oxidise the chloramines — the breakpoint, at roughly 7.6 times the ammonia nitrogen.