http://www.legislation.gov.uk/id/uksi/1996/3001

SCHEDULE 1CRITERIA FOR CLASSIFICATION OF WATERS

Regulations 2, 3(1) and (3), 4(1), 5(3) and (4) and 6(1)

The limits set out below are maxima

No. in Annex II to 75/440/EEC	Parameters	Units		Limits
			DW1	DW2	DW3
2	Coloration (after simple filtration)	mg/1 Pt Scale	20(O)	100(O)	200(O)
4	Temperature	°C	25(O)	25(O)	25(O)
7*	Nitrates	mg/l NO₃	50(O)	50(O)	50(O)
8	Fluorides	mg/l F	1.5
10*	Dissolved iron	mg/l Fe	0.3	2
12	Copper	mg/l Cu	0.05(O)
13	Zinc	mg/l Zn	3	5	5
19	Arsenic	mg/l As	0.05	0.05	0.1
20	Cadmium	mg/l Cd	0.005	0.005	0.005
21	Total chromium	mg/l Cr	0.05	0.05	0.05
22	Lead	mg/l Pb	0.05	0.05	0.05
23	Selenium	mg/l Se	0.01	0.01	0.01
24	Mercury	mg/l Hg	0.001	0.001	0.001
25	Barium	mg/l Ba	0.1	1	1
26	Cyanide	mg/l CN	0.05	0.05	0.05
27	Sulphates	mg/l SO₄	250	250(O)	250(O)
31	Phenols (phenol index) paranitraniline 4-aminoantipyrine	mg/l C₆H₅OH	0.001	0.005	0.1
32	Dissolved or emulsified hydrocarbons	mg/l	0.05	0.2	1
33	Polycyclic aromatic hydrocarbons	mg/l	0.0002	0.0002	0.001
34	Total pesticides (parathion, hexachlorocyclohexane, dieldrin)	mg/l	0.001	0.0025	0.005
39	Ammonium	mg/l NH₄		1.5	4(O)
(O) See regulation 4(1)(b).
* See regulation 4(1)(d).

SCHEDULE 2

Regulation 5(3) and (4)

PART IMETHOD OF MEASURING THE VALUES OF PARAMETERS

No. in Annex II to 75/440/EEC	Parameters	Units	Limit of detection1	Precision2	Accuracy3	Method of measurement	Materials recommended for the container
2	Coloration (after simple filtration)	mg/l Pt Scale	5	10%	20%	Filtering through a glass fibre membrane. Photometric method using platinum-cobalt scale.
4	Temperature	°C	—	0.5	1	Thermometry. Measured in situ at the time of sampling without prior treatment of the sample.
7	Nitrates	mg/l NO₃	2	10%	20%	Molecular absorption spectrophotometry.
8	Fluorides	mg/l F	0.057	10%7	20%7	Molecular absorption spectrophotometry after distillation if necessary. Ion selective electrodes.
10	Dissolved iron	mg/l Fe	0.025	10%5	20%5	Atomic absorption spectrophotometry after filtering through 0.45 μm filter membrane. Molecular absorption spectrophotometry after filtering through 0.45 μm filter membrane.
12	Copper4	mg/l Cu	0.0057	10%7	20%7	Atomic absorption spectrophotometry. Polarography.
13	Zinc4	mg/l Zn	0.02	10%	20%	Atomic absorption spectrophotometry. Molecular absorption spectrophotometry.
19	Arsenic4	mg/l As	0.01	10%	20%	Atomic absorption spectrophotometry. Molecular absorption spectrophotometry.
20	Cadmium4	mg/l Cd	0.001	30%	30%	Atomic absorption spectrophotometry. Polarography.
21	Total chromium4	mg/l Cr	0.01	20%	30%	Atomic absorption spectrophotometry. Molecular absorption spectrophotometry.
22	Lead4	mg/l Pb	0.01	20%	30%	Atomic absorption spectrophotometry. Polarography.
23	Selenium4	mg/l Se	0.005	10%	10%	Atomic absorption spectrophotometry.
24	Mercury4	mg/l Hg	0.0002	30%	30%	Flameless atomic absorption spectrophotometry (cold vaporisation).
25	Barium4	mg/l Ba	0.02	15%	30%	Atomic absorption spectrophotometry.
26	Cyanide	mg/l CN	0.01	20%	30%	Molecular absorption spectrophotometry.
27	Sulphates	mg/l SO₄	10	10%	10%	Gravimetric analysis. EDTA compleximetry. Molecular absorption spectrophotometry.
31	Phenols (phenol index) paranitraniline 4-aminoantipyrene	mg/l C₆H₅OH	0.00057 0.0018	0.00057 30%8	0.00057 50%8	Molecular absorption spectrophotometry 4-aminoantipyrene method. Paranitraniline method.	Glass.
32	Dissolved or emulsified hydrocarbons	mg/l	0.017 0.048	20%7 20%8	30%7 30%8	Infra-red spectrometry after extraction by carbon tetrachloride. Gravimetry after extraction by petroleum ether.	Glass
33	Polycyclic aromatic hydrocarbons4	mg/l	0.00004	50%	50%	Measurement of fluorescence in the UV after thin layer chromatography. Comparative measurements in relation to a mixture of six control substances with the same concentration.	Glass or aluminium.
34	Total pesticides (parathion, hexachloro-cyclohexane, dieldrin)4	mg/l	0.0001	50%	50%	Gas or liquid chromatography after extraction by suitable solvents and purification. Identification of the constituents of the mixture. Quantitative analysis.10	Glass.
39	Ammonium	mg/l NH₄	0.18	10%8	20%8	Molecular absorption spectrophotometry.
1 “Limit of detection” means the minimum value of the parameter examined which it is possible to detect.
2 “Precision” means the range within which 95% of the results of measurements made on a single sample, using the same method, are located.
3 “Accuracy” means the difference between the true value of the parameter examined and the average experimental value obtained.
4 If the samples contain so much suspended matter as to require special preliminary treatment, the accuracy values shown in the above Table may as an exception be exceeded and are to be regarded as a target. These samples must be treated so as to ensure that the analysis covers the largest quantity of substances to be measured.
5 For waters classified as DW1 or DW2.
6 For waters classified as DW3.
7 For waters classified as DW1.
8 For waters classified as DW2 or DW3.
9 Mixture of six standard substances all of the same concentration to be taken into consideration: fluoranthene; 3,4-benzofluoranthene; 11, 12-benzofluoranthene; 3,4-benzopyrene; 1,12-benzoperylene; indeno (1,2,3-cd) pyrene.
10 Mixture of three substances all of the same concentration to be taken into consideration: parathion, hexachlorocyclohexane, dieldrin.

PART IIMINIMUM ANNUAL FREQUENCY OF SAMPLING FOR EACH PARAMETER

Population served	Classification DW1			Classification DW2			Classification DW3
A1	B2	C3	D4	E5	F6	G4	H7	J6
≤10,000	1	1	1	1	1	1	2	1	1
>10,000 to ≤30,000	1	1	1	2	1	1	3	1	1
>30,000 to ≤100,000	2	1	1	4	2	1	6	2	1
>100,000	3	2	1	8	4	1	12	4	1
1 This column applies to the parameters—coloration, temperature and nitrates.
2 This column applies to the parameters—dissolved iron, copper, zinc, sulphates and phenols.
3 This column applies to the parameters—fluorides, arsenic, cadmium, total chromium, lead, selenium, mercury, barium, cyanide, dissolved or emulsified hydrocarbons, polycyclic aromatic hydrocarbons and total pesticides.
4 This column applies to the parameters—coloration, temperature, nitrates and ammonium.
5 This column applies to dissolved iron, zinc, sulphates and phenols.
6 This column applies to the parameters—arsenic, cadmium, total chromium, lead, selenium, mercury, barium, cyanide, dissolved or emulsified hydrocarbons, polycyclic aromatic hydrocarbons and total pesticides.
7 This column applies to the parameters—zinc, sulphates and phenols.