| 1 | 2 | 3 | 4 | 5 |
| Microbiological Safety Requirements | ||||
| Determinand | Unit | Class I
(recommended operational limit) |
Class II
(max. allowable for limited duration) |
Class II water consumption period,a max |
| Allowable compliance contribution a | ||||
| 95% of samples, min. | 4% of samples, max.
|
1% of samples, max. | ||
| E. coli b
or Thermotolerant (faecal) coliform bacteria c |
count/100 mL
count/100 mL |
Not detected
Not detected |
Not detected
1 |
1
10 |
| Total Coliforms count | cfu/100mL | Not detected | Not detected | |
| Heterotrophic Plate Count | Cfu/ml | 1000 | ||
| Cryptosporidium Species | Cfu/10ml | Not detected | ||
| Gardia Species | Cfu/10ml | Not detected | ||
| a The allowable compliance contribution shall be at least 95 % to the limits indicated in column 3, with a maximum of 4 % and 1 %,
respectively, to the limits indicated in column 4 and column 5. The objective of disinfection should, nevertheless, be to attain100 % compliance to the limits indicated in column 3. b Definitive, preferred indicator of faecal pollution. c Indicator of unacceptable microbial water quality, could be tested instead of E. coli but is not the preferred indicator of faecal pollution. Also provides information on treatment efficiency and aftergrowth in distribution networks. |
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| Determinand | Unit | Class I
(recommended operational limit) |
Class II
(max. allowable for limited duration) |
Class II water consumption period,a max |
| Disinfectant residuals | ||||
| Chlorine – Residual | mg/L | <5 | ||
| Monochloramine | mg/L | <3 | ||
| Physical and organoleptic requirements | ||||
| Colour (aesthetic) | Mg/L
Pt |
<20 | 20-50 | No limit |
| Conductivity at 25 ºC | mS/m | <150 | 150-370 | 7 years |
| Total Dissolved solids (aesthetic) | mg/L | < 1 000 | 1 000 – 2 400 | 7 years |
| Odour (aesthetic) | TON | < 5 | 5 – 10 | No limitb |
| pH value at 25 °C (aesthetic/
operational) |
pH
units |
5,0 – 9,5 | 4,0 – 10,0 | No limitc |
| Taste (aesthetic) | FTN | < 5 | 5 – 10 | No limit |
| Turbidity (aesthetic/operational/
indirect health) |
NTU | < 1 | 1 – 5 | No limitd |
| Chemical requirements — macro-determinand | ||||
| Ammonia as N (operational) | mg/L | < 1,0 | 1,0 – 2,0 | No limitd |
| Calcium as Ca (aesthetic/operational) | mg/L | < 150 | 150 – 300 | 7 years |
| Chloride as Cl– (aesthetic) | mg/L | < 200 | 200 – 600 | 7 years |
| Fluoride as F– (health) | mg/L | < 1,0 | 1,0 – 1,5 | 1 year |
| Magnesium as Mg (aesthetic/ health) | mg/L | < 70 | 70 – 100 | 7 years |
| Nitrate as N (health) | mg/L | < 10 | 10 – 20 | 7 years |
| Nitrite as N (health) | mg/L | < 10 | 10 – 20 | 7 years |
| Potassium as K (operational/health) | mg/L | < 50 | 50 – 100 | 7 years |
| Sodium as Na (aesthetic/health) | mg/L | < 200 | 200 – 400 | 7 years |
| Sulfate as SO42- (health) | mg/L | < 400 | 400 – 600 | 7 years |
| Zinc as Zn (aesthetic/health) | mg/L | < 5,0 | 5,0 – 10 | 1 year |
| Chemical requirements — micro-determinand | ||||
| Aluminium as Al (health) | μg/L | < 300 | 300 – 500 | 1 year |
| Antimony as Sb (health) | μg/L | < 10 | 10 – 50 | 1 year |
| Arsenic as As (health) | μg/L | < 10 | 10 – 50 | 1 year |
| Barium | μg/L | <700 | ||
| Boron | μg/L | <2400 | ||
| Cadmium as Cd (health) | μg/L | < 5 | 5 – 10 | 6 months |
| Total Chromium as Cr (health) | μg/L | < 100 | 100 – 500 | 3 months |
| Cobalt as Co (health) | μg/L | < 500 | 500 – 1 000 | 1 year |
| Copper as Cu (health) | μg/L | < 1 000 | 1 000 – 2 000 | 1 year |
| Cyanide (recoverable) as CN– (health) | μg/L | < 50 | 50 – 70 | 1 week |
| Iron as Fe (aesthetic/ operational) | μg/L | < 200 | 200 – 2 000 | 7 yearsb |
| Lead as Pb (health) | μg/L | < 20 | 20 – 50 | 3 months |
| Manganese as Mn (aesthetic) | μg/L | < 100 | 100 – 1 000 | 7 years |
| Mercury as Hg (health) | μg/L | < 1 | 1 – 5 | 3 months |
| Nickel as Ni (health) | μg/L | < 150 | 150 – 350 | 1 year |
| Selenium as Se (health) | μg/L | < 20 | 20 – 50 | 1 year |
| Vanadium as V (health) | μg/L | < 200 | 200 – 500 | 1 year |
| Chemical requirements — organic determinand | ||||
| Dissolved organic carbon as C
(aesthetic/health) |
mg/L | < 10 | 10 – 20 | 3 monthse |
| Total Kjeldahl Nitrogen (TKN) | ||||
| Total trihalomethanes (health)
Bromodichloromethane Dibromochloromethane Bromoform Combined Trihalomethanes |
μg/L
mg/L mg/L mg/L mg/L |
< 200
0.06 0.1 0.1 1 |
200 – 300 | 10 yearsf |
| Phenols (aesthetic/health) | μg/L | < 10 | 10 – 70 | No limitb |
| a The limits for the consumption of class II water are based on the consumption of 2 L of water per day by a person of mass 70 kg over a
period of 70 years. Columns 4 and 5 shall be applied together. b The limits given are based on aesthetic aspects. c No primary health effect – low pH values can result in structural problems in the distribution system. d These values can indicate process efficiency and risks associated with pathogens. e When dissolved organic carbon is deemed of natural origin, the consumption period can be extended. f This is a suggested value because trihalomethanes have not been proven to have any effect on human health. |
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