New Cryptosporidium Water Standards Delayed

Tightening of Ministry of Health Cryptosporidium drinking-water standards delayed

A new Ministry of Health water standard that would lower the existing limit of the fine particles in drinking water left over from filtering and treating it, has been deferred.

The new standard, which was planned to be in force by the first of January next year, sets lower limits for turbidity (due to particles) to reduce the risk from Cryptosporidium, a common contaminant in New Zealand waters. This can cause diarrhoea and other more serious problems in some people.

A set of revised water standards will come into force in July 2005. They will allow alternative ways of reducing the risk from Cryptosporidium from water treatment plants that cannot meet the new turbidity standard.

To enable suppliers to take advantage of the new options in the revised standard, the planned amendments will be delayed until July 2005.

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BACKGROUND

The Drinking-Water Standards for New Zealand 2000 required that by 1 January 2005, 95 per cent of turbidity measurements on the filter effluent from a chemical coagulation and filtration treatment unit should not exceed 0.1 turbidity units (NTU).

This target was set to protect drinking-water consumers from Cryptosporidium. This standard was based on chemical coagulation and filtration being the only treatment received by the water.

New knowledge has made it possible to incorporate an allowance for the additional effect of other types of treatment in the revised Drinking-Water Standards for New Zealand 2005. This will provide alternative options for providing protection from Cryptosporidium. With these additional treatments in place, sufficient protection against Cryptosporidium is provided and it is not be necessary for the 0.1 NTU turbidity requirement to be met.

Accordingly, the Director-General of Health has authorised the 0.1 NTU requirement that was due to come into effect on the 1 January 2005 being held in abeyance until the revised Drinking-Water Standards for New Zealand 2005 come into effect on 1 July 2005.