# The Bathing Waters (Classification) Regulations 1991, Schedule 3: QUALITY AND ADDITIONAL SAMPLING REQUIREMENTS


Parameter
Parametric value
Minimum sampling frequency
Methods of analysis and inspection
Notes
1. Samples may be taken at intervals of four weeks where samples taken in previous years show that the waters are of an appreciably higher standard than that required for the classification in question and the quality of the waters has not subsequently deteriorated and is unlikely to do so.
2. Samples must be taken in relation to this parameter when there are grounds for suspecting that there has been a deterioration in the quality of the waters or the substance is likely to be present in the waters.
Micro-biological:
Total coliforms
10,000/100ml
Fortnightly (see Note 1)
Fermentation in multiple tubes. Sub-culturing of the positive tubes on a confirmation medium. Either counting according to MPN (most probable number) or membrane filtration, culturing on an appropriate medium, sub-culturing and identification of the suspect colonies.
Faecal coliforms
2,000/100ml
Fortnightly (see Note 1)
The incubation temperature is variable according to whether total or faecal coliforms are being investigated.
Salmonella
Absent in 1 litre
(see Note 2)
Membrane filtration, culturing on an appropriate medium, sub-culturing and identification of the suspect colonies.
Entero viruses
No plaque forming units in 10 litres
(see Note 2)
Concentration (by filtration, flocculation or centrifuging) and confirmation.
Physico-chemical:
PH
6 to 9
(see Note 2)
Electrometry with calibration at pH 7 and 9.
Colour
No abnormal change in colour
Fortnightly (see Note 1)
Visual inspection or photometry with standards on the platinum cobalt scale.
Mineral oils
No film visible on the surface of the water and no odour
Fortnightly (see Note 1)
Visual and olfactory inspection.
Surface-active substances reacting with methylene blue
No lasting foam
Fortnightly (see Note 1)
Visual inspection.
Phenols (phenol indices)
No specific odour
Fortnightly (see Note 1)
Olfactory inspection.
≤0.05 mg/litre (C6H5OH)
(see Note 2)
Absorption spectrophotometry 4-aminoantipyrine (4 AAP)
Transparency
1 metre
Fortnightly (see Note 1)
Secchi’s disc.

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Source: https://www.legislation.gov.uk/uksi/1991/1597/schedule/3 (the official version)
Page: https://openlegislation.uk/bathing-waters-classification-regulations-1991/schedule-3
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.