The aim of the project is to obtain detailed information on the sodium hypochlorite solutions available on the market and the chlorate content of the products supplied to water supply companies, as well as on the chlorate formation as a function of the storage conditions. The project process should generate the pre-requisites for revising the relevant standard for sodium hypochlorite.
For sodium hypochlorite, DIN EN 901 specifies a permitted sodium chlorate level of 5.4 % based on the chlorine concentration. If a product with this chlorate content is supplied, the maximum value of chlorate in drinking water of 70 µg/l at a dosage of 1.2 mg/l chlorine can no longer be reliably fulfilled. This is important if chlorate is formed during storage of sodium hypochlorite. For this reason, DVGW initiated a revision of DIN EN 901 to more strongly restrict the chlorate content in sodium hypochlorite solutions.
This requires more detailed information to be provided on the available products and delivery routes. The aim is to research further possibilities of limiting chlorate formation en route from the manufacturer via the retailer to the water supply company.
In addition, the project also aims to draft specifications for the incoming goods control and storage of sodium hypochlorite solutions to avoid/reduce chlorate formation.