Ensuring drinking water quality standards: From source to the tap

Drinking water quality standards evaluation is evolving from checking at the tap towards holistic safety management starting at source, to safeguard human health and the environmental integrity of all water.

Waterborne diseases are the world’s leading cause of death, killing more people than war, terrorism and weapons of mass destruction combined, according to the World Health Organisation (WHO). Diarrhoea alone kills around 1.8 million people every year, mostly children in developing countries, as a result of unclean water and poor sanitation, the WHO estimates . In an attempt to protect public health, the WHO publishes guidelines for safe drinking water that serve as a reference for both developed and developing countries when setting national standards.

These include two types of water quality parameters. Health guidelines give limit values for microbial, chemical and radiological constituents that have a direct impact on human health, while aesthetic guidelines deal with parameters that might not be harmful to life but give water an unpleasant taste or odour.

But as advances in quality surveillance continue to improve knowledge of residual chemicals such as pesticides in drinking water, moving towards risk management across the entire production and distribution cycle of drinking water has become imperative, rather than simply checking at the tap.

New WHO guidelines introduced in 2004 first put forward the idea in the context of Water Safety Plans aimed at minimising the contamination of source water, reducing contamination at the water treatment stage and preventing it during the storage, distribution and handling of drinking water.

The European Union follows suit

In line with new science, the European Union has also started reviewing its water policy in recent years to ensure a life-cycle approach to water treatment.

The EU has a whole body of water legislation, but 1998's Drinking Water Directive has the most direct impact on how drinking water is managed by the bloc's member states. It sets minimum quality standards at the tap based on the WHO guidelines, with the stated objective of providing EU citizens with “wholesome and clean” water.

As well as monitoring and testing the most common microbiological and chemical parameters, EU countries are obliged to regulate additional substances on their territory where relevant.

The European Commission launched a public consultation in 2003 to move towards comprehensive risk management from source to the end of the water pipe. While there was no immediate need to recast the wide-ranging parameters and monitoring requirements that member states are still in the process of implementing, the idea was to bring drinking water legislation in line with the 2000 Water Framework Directive, which foresaw river basin management plans as a means of ensuring a healthy status for all water.

The water services industry hopes that river basin management will help address the problem of residual chemicals that end up in water.

Nitrate contamination in drinking water is a common problem across Europe as a result of intensive agriculture and use of fertilisers, according to the European Environment Agency (EEA). In addition, many countries face problems with pesticides and metal contamination.

To read more about government drinking water policies, please follow these links:

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