Drinking Water Quality (residual chlorine)

Indicator Phrasing

% of [select: targeted water points / household water samples] with free residual chlorine between 0.2 and 0.5 mg/l

Indicator Phrasing

English: % of [select: targeted water points / household water samples] with free residual chlorine between 0.2 and 0.5 mg/l

French: % de [sélectionner: points d’eau cibles/ échantillons d’eau domestique] contenant de 0.2 à 0.5 mg de chlore résiduel libre par litre

Spanish: % de [seleccione: puntos de agua objetivo / muestras de agua de los hogares] con cloro residual libre entre 0,2 y 0,5 mg/l

Portuguese: % de [selecione: pontos de água-alvo / amostras de água de agregados familiares] com cloro livre residual entre 0.2 e 0.5 mg/l

Czech: % [určete: cílových vodních zdrojů / vzorků vody domácností] s přítomností volného chloru v hodnotách od 0.2 do 0.5 mg/l

What is its purpose?

This indicator measures if disinfection of the drinking water is correctly implemented at the source level or the household level.

How to Collect and Analyse the Required Data

1) Consult your WASH advisor and/or relevant WASH authorities on how to measure free residual chlorine using a pool tester.

2) Ensure that the water samples are collected from all targeted water points or from a representative sample of households.

3) To calculate the indicator's value, divide the number of targeted water points / household water samples with the correct level of free residual chlorine by the total number of assessed water samples. Multiply the result by 100 to convert it to a percentage.

Important Comments

1) Measuring free residual chlorine is cheaper and faster than measuring faecal contamination but is only applicable when drinking water is disinfected either at the water source or by the household itself (with aquatabs or other similar reagent).

2) At the source level, this indicator will give a sense of the quality of the water committees’ work. At the household level, this indicator assesses the correct usage of the reagent.

3) BHA phrases the indicator slightly differently, as "percent of households whose drinking water supplies have a free residual chlorine (FRC) > 0.2 mg/L".

Access Additional Guidance

WHO (2011) Guidelines for Drinking-Water Quality (.pdf)
Global WASH Cluster

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