Parameters

Expression of the Results

Guide Level (GL)

Maximum Admissible Concentration(MAC)

Comments

Colour

Hazen Units

1

20

-

Turbidity

NTU Units

0.4

4

-

Odour

Dilution number

0

2 at 12C,  3 at 25C

-

Taste

Dilution number

0

2 at 12C,  3 at 25C

-

Hydrogen ion conc.

pH   unit

6.5 - pH - 8.5

5.5 (MRC) to 9.5

MRC Minimum required Conc.

Conductivity

at  20C

400

1500

-

Chloride

Cl   mg / L

25

400

above 200 mg/L may affect taste and corrosivity of water

Sulphate

SO4   mg / L

25

250

Excessive concentration can cause gastrointestinal irritation when magnesium or sodium present

Calcium

Ca   mg / L

100

250

Scale formed at excessive concentration

Magnesium

Mg   mg / L

30

50

-

Sodium

Na   mg / L

20

175

-

Potassium

K   mg / L

10

12

-

Aluminium

Al   mg / L

0.05

0.2

-

Total Hardness

Ca   mg / L

-

-

60 mg/L (MRC) in softened water

Alkalininty

HCO3   mg / L

-

-

30 mg/L (MRC) in softened water

Nitrates

NO3   mg / L

25

50

Above 50 mg / L infants under 6 months at risk. Above 100 mg/L, low nitrate bottled water should be made available for infants.

Nitraites

NO2   mg /

-

0.1

-

Ammonium

NH4   mg / L

0.05

0.5

Excessive concentration encourages growth of organisms corrosion in pipes and less effective chlorination

Kjeldahl Nitrogen (excluding N in NO2 and NO3)

N   mg / L

-

1

-

Total Organic Carbon (TOC)

C  mg / L

-

-

The reason for any increase in the usual concentrationmust be investigated

Dissolved or emulsified hydrocarbons (after extraction by petroleum ether); Mineral oils

Microgram / Litre

-

10

-

Phenols (phenol index)

C6H5OH  (microgram / Litre

-

0.5

Excluding natural phenols which do not react to chlorine

Surfactants (reacting with methylene blue)

microgram / Litre (Lauryl sulphate)

-

200

-

Other organochlorine compounds not covered by pesticides etc

microgram / Litre

1

100 of chlorine containig trihalomethanes

haloform concentrations must be as low as possible, taking account of the need for adequate chlorination

Iron

Fe   microgram / Litre

50

200

High concentrations affect taste, colour and turbidity; cause staining of laundry etc and aid growth of deposits in pipes

Manganes

Mn    microgram / Litre

20

50

(as for iron)

Copper

Cu   microgram / Litre

100*,  300*

3000

Applies to any sample. Concentration affected by the nature of pipework but water as supplied at the curtilage should not be aggressive. Remedial action by the water supplier is required if 1000 microgram/Litre is exceeded frequently or to an appreciable extent. Above 3000 microgram/Litre astringent taste, discolouration and corrosion may occur

Zinc

Zn   microgram / Litre

100*,   5000*

5000

(as for copper but 2000 microgram/Litre).   Above 5000 microgram/Litre astringent taste,   opalescence and sand-like deposits may occur

Phosphorus

P2O5   microgram / Litre

400

5000

-

Fluoride

F   microgram / Litre   8 - 12C
  25 - 30C

-

 
1500
  700

MAC varies according to average air temperature

Residual Chlorine 

Cl   microgram / Litre

100

300              
50 ( MRC )

As FREE chlorine unless 2 hours contact time is provided for combined chlorine to be effective

Barium

Ba   microgram / Litre

100

1000

-

Silver

Ag   microgram / Litre

-

10

If, exceptionally, silver is used non-systematically to process the water, a MAC value of 80microgram/Litre may be authorised

Parameters

Expression of the Results

Guide Level (GL)

Maximum Admissible Concentration(MAC)

Comments

Arsenic

As   microgram / Litre

-

50

Possible sources weed killers, sheep dipping, tin mining waste

Cadmium

Cd   microgram / Litre

-

5

Possible source - plated fitting

Chromium

Cr   microgram / Litre

-

50

-

Mercury

Hg   microgram / Litre

-

1

Possible source - mercury manometers

Nickel

Ni   microgram/Litre

-

50

Possible source - chrome or other plated fittings

Lead

Pb   microgram/Litre

-

50

Where lead pipes are present, the lead content should not exceed 50 microgram / Litre in a sample taken after flushing.   If the sample is taken directly or after flushing and the lead content either frequently or to an appreciable extent exceeds 100 microgram / Litre, suitable measures must be taken to reduce the exposure to lead on the part of the consumer

Antimony

Sb   microgram / Litre

-

10

-

Selenium

Se   microgram / Litre

-

10

-

Pesticides & related products - substances considered
separately

microgram / Litre

-

0.1

pesticides and related products means :
- insecticides : persistent organochlorine compounds, organophosphorous compounds
- carbamates
- herbicides
- fungicides
- PCBs and PCts

Total

-

-

0.5

-

Polycyclic Aromatic Hydrocarbons

microgram / Litre

-

0.2

- Reference substances :
- fluoranthene,
benzo 3.4 fluoranthene,
benzo 11.12 fluoranthene,
benzo 3.4 pyrene,
benzo 1.12 perylene,
indeno (1 , 2 , 3 -cd) pyrene