The Bathing Waters (Classification) Regulations 1991

Regulation 2(3)

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.