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.
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.