General information:
By residual chlorine it is understood:
- free residual chlorine in the form of elemental chlorine (Cl2), hypochlorous acid (HOCl) or hypochlorite (ClO-);
- residual chlorine bound in the form of chloramines or dichloramides;
- Total residual chlorine, consisting of free residual chlorine and bound residual chlorine.
Referential after which the analysis is performed:
The analysis for the determination of residual chlorine in drinking water is performed within its own laboratory according to the standard national SR EN ISO 7393/2002.
Principle of the method:
The determination of residual chlorine in drinking water is performed by titrating in the presence of sulfuric acid respectively potassium bromide with methyl-orange until the color of the solution is turned pink.
Sample rejection cases – quantity of inappropriate sample, sample collected in inappropriate containers, samples not properly labelled, etc.
Recipient – clean container.
The amount of sample required to perform the analysis - minimum 210ml.
Previous processing after harvesting – -
Stable sample – freshly harvested water is stable for 2 days at 2-8°C or 1 hour at ambient temperature.
The analysis method - volumetrica.
Reference values according to the Water Law1)
| Parameter / Unit of measurement | CA value (Maximum permissible concentration) |
|
|
0,1-0,5 |
*) The cma value range must be respected in the distribution network (branching, end of the network).
Recommendations for performing the analysis/ Effects of exceeding the reference values –
The disinfection of chlorine water, has played and still plays an important role in reducing the diseases spread by water through the microorganisms contained in it, but this residual chlorine remaining in drinking water in large quantities can become toxic (its carcinogenic effect is known in the long term).
For the reduction of residual chlorine in drinking water, a special installation is used.
Bibliography:
- LEGEA 458/2002 as amended and supplemented by Law no. 311/2004, Government Ordinance no. 11/2010, Law no. 124/2010 and Government Ordinance no. 1/2011
