Water is one of the most comprehensively regulated areas of EU environmental legislation. The European Union has firm principles upon which its approach to water management is based:

• High level of protection: In the context of water management, this requires that the level of protection of human health, of water resources and of natural ecosystems should be ambitious, not setting for the minimum acceptable level but instead aiming at a high level of protection.
• Precautionary principle: Given the fact that the scientific knowledge base is incomplete - both in relation to our understanding of water systems and, in particular, regarding the impacts of pollution on human health and the health of the environment - the precautionary principle leaves a margin for error. According to this principle, policy should always be based on recognised scientific knowledge, but it should err on the side of caution whenever there are doubts or insufficient information.
• Prevention principle: This principle recognises the moral duty to prevent damage to the environment. It also recognises the difficulty and cost of reversing or rectifying damage to the environment.
• Polluter pays principle: Those who use water and produce wastewater or contaminate the environment should pay the full costs of their actions. This principle helps prevent distortion in competition by ensuring that external costs are included in the production costs, and acts as an incentive towards the effective control of pollution at the source.
• Rectification of pollution at the source: This principle follows logically from the "prevention principle", but applies once environmental damage has been identified. Wherever possible, action should be taken to rectify the pollution at its source, rather than seeking technical solutions to solve the problem "downstream".

The first wave of European water legislation began with the Surface Water Directive in 1975 and culminated in the Drinking Water Directive in 1980. Legislation focused mainly on water quality objectives for particular water types and uses, such as fishing waters, shellfish water, bathing waters and groundwater. A 1988 review of European water legislation was based more on an emission limit value approach, which resulted in important new directives in 1991 on urban wastewater treatment and on the protection of waters against pollution by nitrates from agricultural sources.

For the future, a new European "Water Framework Directive" will be adopted in 2000. It requires integrated water management planning in river basins based on a combined approach of water quality standards and emission limit values. This new legislation will also expand the scope of water protection to all waters, surface waters and groundwater, and set an obligation to achieve good status for all these waters within a set deadline.

The provision of both water and sewerage services is to a large extent the responsibility of local authorities or water bodies. This includes making sure that drinking water is safe and that wastewater is properly disposed of (according to EU standards), in order to minimise public health risks. Local authorities may be responsible for the construction or upgrading of water and wastewater treatment plants, water mains and sewer networks. And they will have to justify their actions to citizens and explain why investment is needed in water collection and purification, which may lead to higher costs for individual households.

The costs of achieving compliance with the EU water standards will, in some cases, be very high. The most efficient way to tackle this task is to construct a local or regional, if appropriate, medium- or long-term water management strategy.

Drinking Water

The Drinking Water Directive establishes strict quality standards for drinking water at the tap. It requires local authorities to:

• meet the strict quality standards for water destined for human consumption;
• monitor the organoleptic (relating to the way the water smells, tastes and looks) and microbiological quality of drinking water; (see footnote );
• and provide information to the public on the quality of drinking water.

In order to meet the new strict drinking water quality standards, local authorities will have to ensure suitable treatment of drinking water. The major types of drinking water treatment technologies include:

• disinfections (e.g. chlorination or ultraviolet radiation), to kill disease-causing micro-organisms, such as viruses, bacteria and some parasites;
• organic removal (e.g. aeration), for removal of organic contaminants such as pesticides and solvents;
• inorganic contaminants removal (e.g. coagulation and settling), for removal of inorganic contaminants such as cadmium, chromium, arsenic, silver and lead.

Wastewater

The Urban Wastewater Treatment Directive aims to prevent environmental damage done through discharge of urban wastewater and wastewater from industrial processes. It requires that, in the majority of cases, local authorities (above 2,000 population equivalent, p.e.) provide for sewerage systems for collecting wastewater and make sure that sewerage discharges will receive at least secondary treatment, i.e. biological wastewater treatment. More advanced treatment is required for water discharged into so-called sensitive areas (i.e. water bodies subject to, or in danger of, eutrophication).

Wastewater treatment can be divided into roughly three (consecutive) steps and a preliminary process called pre-treatment:

• Pre-treatment is the removal of stones, sand and fat/grease using mechanical processes such as screening, settlement or flotation.
• Primary treatment is a removal of suspended solids by passing wastewater through settlements or flotation tanks.
• Secondary treatment is a biological treatment in which water passes through tanks where bacteria transform dissolved biodegradable pollutants into sludge.
• Tertiary treatment is the removal of nutrients, and/or the disinfection by chlorination, ultraviolet radiation or ozone treatment.