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The Private Water Supplies Regulations 1991

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Regulation 2(1)


Table A

ItemParametersUnits of MeasurementConcentration or Value (maximum unless otherwise stated)
Note: (i) If silver is used in a water treatment process, 80 may be substituted for 10.
1.Colourmg/1 Pt/Co scale20
2.Turbidity (including suspended solids)Formazin turbidity units4
3.Odour (including hydrogen sulphide)Dilution number3 at 25°C
4.TasteDilution number3 at 25°C
6.Hydrogen ionpH value


5.5 (minimum)

7.Sulphatemg SO4/1250
8.Magnesiummg Mg/150
9.Sodiummg Na/1150
10.Potassiummg K/112
11.Dry residuesmg/11500 (after drying at 180°C)
12.Nitratemg NO3/150
13.Nitritemg NO2/10.1
14.Ammonium (ammonia and ammonium ions)mg NH4/10.5
15.Kjeldahl nitrogenmg N/11
16.Oxidisability (permanganate value)mg O2/15
17.Total organic carbonmg C/1No significant increase over that normally observed
18.Dissolved or emulsified hydrocarbons (after extraction with petroleum ether); mineral oilsμg/110
19.Phenolsμg C6H5OH/10.5
20.Surfactantsμg/1 (as lauryl sulphate)200
21.Aluminiumμg Al/1200
22.Ironμg Fe/1200
23.Manganeseμg Mn/150
24.Copperμg Cu/13000
25.Zincμg Zn/15000
26.Phosphorusμg P/12200
27.Fluorideμg F/11500
28.Silverμg Ag/110(i)

Table B

ItemParametersUnits of MeasurementMaximum Concentration



The sum of the detected concentrations of individual substances.


The sum of the detected concentrations of fluoranthene, benzo 3.4 fluoranthene, benzo 11.12 fluoranthene, benzo 3.4 pyrene, benzo 1.12 perylene and indeno (1,2,3-cd) pyrene.

1.Arsenicμg As/150
2.Cadmiumμg Cd/15
3.Cyanideμg CN/150
4.Chromiumμg Cr/150
5.Mercuryμg Hg/11
6.Nickelμg Ni/150
7.Leadμg Pb/150
8.Antimonyμg Sb/110
9.Seleniumμg Se/110

Pesticides and related products:


individual substances


(b)total substances(i)

11.Polycyclic aromatic hydrocarbons(ii)μg/10.2

Table C

ItemParametersUnits of MeasurementMaximum Concentration
Note: (i) Analysis by multiple tube method.
1.Total coliformsnumber/100 ml0
2.Faccal coliformsnumber/100 ml0
3.Faccal streptococcinumber/100 ml0
4.Sulphite-reducing clostridianumber/20 ml≤1(i)
5.Colony countsnumber/1 ml at 22°C or 37°CNo significant increase over that normally observed

Table D(i)

ItemParametersUnits of MeasurementMaximum Concentration or Value
Note: (i) See regulation 3(3)(d).
1.ConductivityμS/cm1500 at 20°C
2.Chloridemg Cl/1400
3.Calciummg Ca/1250
4.Substances extractable in chloroformmg/1 dry residue1
5.Boronμg B/12000
6.Bariumμg Ba/11000
7.Benzo 3,4 pyreneμg/110

Table E

ItemParametersUnits of MeasurementMinimum Concentration(i)
Note: (i) See regulation 3(4).
1.Total hardnessmg Ca/160
2.Alkalinitymg HCO3/130

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