Tap water, drinking water, public distribution water, quality

Exceeding the quality limits for water intended for human consumption
Assessment of the health hazards

In 1998, an European directive (1) on drinking water reinforced health protection by laying down new quality criteria for drinking water. This directive also provided for the possibility of exceeding these quality limits, subject to a derogation being granted and provided that:

- the situation is only temporary;
- measures are taken to restore the water quality;
- there is no other reasonable means for maintaining the supply of water;
- a maximum value be set and applied to ensure that public health is protected during this period.

These new quality requirements and regulations enabling exceeded quality limits to be managed have been transposed into the French public health code.
The Directorate General for Health sent a request to Afssa in 2003 to enable the health authorities to set the necessary derogation limits for County-level Directorates of Health and Social Affairs to manage situations where quality limits are exceeded.
The purpose of this request was to assess the health risks associated with the consumption of water with higher levels of a series of physicochemical parameters than the quality limit.
In 2007, an interim report on 16 parameters (2) was produced by the Agency. Since then, datasheets and opinions have been published on four additional substances (3).

For each physicochemical parameter, Afssa has drawn up a datasheet that the public authorities can use to take suitable measures for protecting public health (by restricting or banning use for all or part of the population if necessary).

On each datasheet, the health authorities can find out the origin of each substance in the water, the treatment processes that can be applied to restore water quality, the health effects, the proportion of total intake coming from water, the human toxicity values and characterisation of the health hazard.

For each carcinogenic substance, Afssa has also indicated the probability of increase in cancer risk associated with the health standards being exceeded over 3, 6 and 9 years for different concentrations. The health authorities must then adopt one of these limits as a derogation value, based on the risk that is considered to be acceptable.

For other substances, the Agency has set a concentration limit below which the consumption of water over a 3 to 9 year period does not pose a danger to health.

This work will be continued with the drawing up of individual datasheets for substances referred to in the request that have still not been addressed, and will be subject to regular updating.

(1) directive 98/83/CE
(2) antimony, chlorites, fluorides, lead, arsenic, selenium, vinyl chloride, aluminium, sulfates, chlorides, benzo[a]pyrene, PAH, nickel, copper, tri and tetrachloroethylene, pesticides.
(3) barium, nitrates, nitrites and bromates

December 2008