This Directive prohibits the direct or indirect discharge into groundwater of List I substances and limits discharges of List II substances so as to avoid pollution.

The Directive does not apply to:

• Discharges of domestic effluents from isolated dwellings not connected to a sewerage system and situated outside areas protected for the abstraction of water for human consumption;
  
  
• Discharges which are found by the competent authority of the Member State concerned to contain substances in lists I or II in a quantity and concentration so small as to obviate any present or future danger of deterioration in the quality of the receiving groundwater;
  
  
• Discharges of matter containing radioactive substances.
  
  
  

Prior investigation is required to determine the suitability, or otherwise, of those discharges to which the Directive applies.

However, if prior investigation reveals that the groundwater is permanently unsuitable for other uses, especially domestic or agricultural, SEPA may authorise the discharge of these substances provided that their presence does not impede exploitation of ground resources and that all technical precautions have been taken to ensure that these substances cannot reach other aquatic systems or harm other ecosystems. In addition, following prior investigation SEPA may authorise discharges due to re-injection into the same aquifer of water used for geothermal purposes, water pumped out of mines and quarries or water pumped out for civil engineering works.

The Directive is implemented in Scotland by the Water Environment (Controlled Activities) (Scotland) Regulations 2005.

A more comprehensive list of List I and List II substances have been established and can be seen by clicking here.