Water quality samples are taken at each bathing water throughout the bathing season, from 1 June to 15 September. A pre-season sample is taken during the last fortnight in May.
EU water quality classifications are calculated at the end of the season and apply to each bathing water for the duration of the following season.
Most bathing waters are sampled 18 times during the season. Some geographically remote sites are sampled 10 times. Sites which have consistently demonstrated excellent water quality are sampled five times. Investigative work is undertaken to eliminate or minimise the sources of pollution which still have an intermittent adverse effect on several designated bathing waters.
The new Bathing Water Directive
The new Bathing Water Directive (2006/7/EC) came into force on 24 March 2006 and was translated into Scottish law by The Bathing Waters (Scotland) Regulations 2008.
The Directive, now fully implemented, introduced a new classification system with more stringent water quality standards and puts an emphasis on providing information to the public.
What we measure
Changes were made in 2012 to the bacterial entities monitored. These arise from recommendations from the World Health Organization. In place of the previous coliform and faecal streptococci standards, the new directive sets standards for Escherichia coli and intestinal enterococci. While slightly altering the microbiological analytical techniques necessary, the differences in the values obtained are considered to be minimal.
Sampling schedules (the monitoring calendar) are set and fixed in advance of the bathing season as required by Regulations. At sites which have daily real time forecasting of bathing water quality and electronic beach message signage we may use the allowed five day sampling window to avoid sampling when the sign gives a poor water quality warning and we have actively advised against bathing. At all other sites we sample on the date in the monitoring calendar unless there is an unexpected operational reason e.g. vehicle breakdown.
Short term pollution
Our electronic signage network at 29 sites across Scotland provides real-time predictions of bathing water quality. These electronic signs enable us to remove (from the overall classification dataset) samples collected during short-term pollution events, when there is a public warning system in place to inform prospective bathers of potentially poorer water quality. A separate closure sample must have been taken to demonstrate that the event has ended and management measures must be in place to prevent, reduce or eliminate the causes of the pollution. The Directive says that a maximum of 15% of the samples used to assess the classification of a bathing water can be disregarded from the assessment and, if necessary, replaced.
An abnormal situation is defined by the Bathing Water Directive as an event or combination of events impacting on bathing water quality at the location concerned and not expected to occur on average more than once every four years. During an abnormal situation the monitoring calendar can be suspended so that samples which assess compliance of the bathing water are not taken. This is because they are unrepresentative of the water quality of a bathing water. When an abnormal situation is in force, signs must be put up by the beach controller warning the public of the nature and expected duration of the pollution.
Bacteriological analysis is carried out at our specialist microbiological laboratories in North Lanarkshire and Aberdeen. All of these laboratories operate to United Kingdom Accreditation Service quality systems for their analytical work. We also participate in external inter-laboratory testing schemes such as those run by the Public Health Laboratory and Aquacheck. The inter-laboratory testing has demonstrated consistent high accuracy of our bacteriological test results.