Microbiological Parameters

Check

Audit

1

Escherichia coli (E. coli)

0

No./100ml

The E. coli  bacteria is present in very high numbers in human or animal faeces and is rarely found in the absence of faecal pollution.  As such, its presence in drinking water is a good indication that either the source of the water has become contaminated or that the treatment process at the water treatment plant is not operating adequately. 

Yes

Yes

2

Enterococci

0

No./100ml

Enterococci originate in human or animal waste and thus their presence provides an indication that the water supply has been contaminated with faeces

Yes

Chemical Parameters

3

Acrylamide

0.10

mg/l

Acrylamide can be present in water supplies from the use of polyacrylamides as coagulant aids in water treatment.  It is classified by the International Agency for Research on Cancer (IARC) in Group 2A (i.e., probably carcinogenic to humans). 

Note 1

4

Antimony

5.0

mg/l

Antimony is a naturally occurring trace element used in the metal industry and in flame retardant materials.  It can also occur naturally from weathering of rocks.  The toxicity of antimony depends on the form it occurs in (naturally occurring antimony is likely to be in the less toxic form) and while there is some evidence for the carcinogenicity of certain antimony compounds by inhalation, there is no data to indicate carcinogenicity by the oral route.

Yes

5

Arsenic

10

mg/l

Arsenic is widely distributed through-out the Earth’s crust and is used in certain industrial applications (primarily as alloying agents in the manufacture of transistors, lasers and semi-conductors) and has been used in the past as a component of the wood preservative CCA (Copper-Chromium-Arsenic) though it is no longer in use.  However, the primary source of arsenic in drinking water is from its dissolution into groundwater from naturally occurring ores and minerals. 

Arsenic has been shown to have significant health effects in some parts of the world (e.g. Bangladesh).  Arsenic is one of the few substances shown to cause cancer in humans through consumption of drinking water and there is overwhelming evidence that consumption of arsenic through drinking water is causally related to the development of cancer in several different locations in the body.

Yes

6

Benzene

1.0

mg/l

The principle source of benzene is from vehicle emissions which may find their way into water.  Benzene is carcinogenic to humans. 

Yes

7

Benzo(a)pyrene

0.010

mg/l

Benzo(a)pyrene was formerly included in the group of chemicals called PAHs (Polycyclic Aromatic Hydrocarbons) which are generally undesirable in water.  The absolute undesirability of benzo(a)pyrene in drinking water has been emphasised by its inclusion as a separate parameter.  It is carcinogenic. 

Yes

8

Boron

1.0

mg/l

Boron is a naturally occurring element and can occur naturally in groundwater.  It is also used in the manufacture of glass, soap, and detergents and as flame retardants.  Development toxicity has been demonstrated in laboratory animals at levels in excess of the parametric value. 

Yes

9

Bromate

10

mg/l

Bromate is classified by the International Agency for Research on Cancer (IARC) in Group 2B (i.e., possibly carcinogenic to humans).  Bromate is not normally found in water but may be formed during ozonation when the bromide ion is present in water.  Under certain conditions, bromate may also be formed in concentrated hypochlorite solutions used to disinfect water (WHO, 2004).

Note 2

Yes

10

Cadmium

5.0

mg/l

Cadmium is used in the steel and plastics industry and is a common component of batteries.  It may also enter water from trace impurities in the zinc of galvanised pipes and solders and some metal fittings.  Cadmium can accumulate in the kidneys. 

Yes

11

Chromium

50

mg/l

Chromium is commonly found in the Earth’s crust, though can be present in water from contamination from timber treatment chemicals (Copper-Chromium-Arsenic).  The toxicity of chromium depends on the form in which it is found, with hexavalent chromium classified as a human carcinogen.

Yes

12

Copper

2.0

mg/l

Copper is a nutrient essential for health, though at elevated levels can become a contaminant (elevated levels can cause acute gastrointestinal effects).  The primary source of copper in drinking water is from corrosion of internal copper plumbing.  The levels of copper in drinking water depend on the length of time the water has been stagnant in the copper piping and thus fully flushed water generally has low levels of copper. 

Note 3

Yes

13

Cyanide

50

mg/l

Cyanide is a reactive, highly toxic entity, which, in excessive amounts, will cause mortality to humans.  It is a common constituent of industrial wastes, especially from metal plating processes and electronic components manufacture. 

Yes

14

1,2-dichloroethane

3.0

mg/l

1,2-dichloroethane is a synthetic intermediate and organic solvent used in the manufacture of chemicals.  It can enter water from discharges from facilities using the chemical.  It is a toxic substance which can cause a variety of ill-effects including eye damage, dermatitis and narcotic effects.  It has also been classified by the IARC in Group 2 (possible human carcinogen). 

Yes

15

Epichlorohydrin

0.10

mg/l

Epichlorohydrin can be present in water supplies from the use of polyamines as coagulant aids in water treatment and from epoxy resin linings of water mains and water retaining structures.  It is classified by the International Agency for Research on Cancer (IARC) in Group 2A (i.e., probably carcinogenic to humans). 

Note 1

16

Fluoride

0.8

mg/l

Fluoride arises almost exclusively from fluoridation of public water supplies and from industrial discharges, although it occurs naturally in quite rare instances. Past health studies have shown that the addition of fluoride to water supplies at levels above 0.6mg/l F^- leads to a reduction in tooth decay in growing children and that the optimum beneficial effects were thought to occur around 1.0 mg/l. However, in light of recent international and Irish research which shows an increasing occurrence of dental fluorosis, the Forum on Fluoridation (2002) recommended the lowering of the fluoride levels in drinking water to a range of 0.6 to 0.8 mg/l, with a target of 0.7 mg/l. 

Note 11

Yes

17

Lead

10

mg/l

Lead is present in drinking water primarily from its dissolution from lead pipes or lead-containing solder and thus the concentration of lead in drinking water depends on a number of factors including pH, temperature, water hardness and standing time of the water.  Consequently, the method of sampling for lead is critical and depending on the method used results can vary significantly.  According to the World Health Organisation (WHO, 2004) lead is a general toxicant that accumulates in bone.  Infants, children up to 6 years of age and pregnant women are the most susceptible to its health effects.  It is toxic to both the central and peripheral nervous systems.

Notes 3 and 4

Yes

18

Mercury

1.0

mg/l

Mercury is a very toxic metal that primarily effects the kidney.  It has been used in electrical appliances, batteries, plastics and in dental amalgams, though many of these uses are no longer applicable.  

Yes

19

Nickel

20

mg/l

Nickel is a metal used in the production of stainless steels and alloys and thus may be present in drinking water from water that comes into contact with nickel or chromium plated taps particularly where the water has been stagnant prior to consumption.  Nickel compounds are carcinogenic and metallic nickel is possibly carcinogenic. 

Note 3

Yes

20

Nitrate

50

mg/l

Nitrate in the environment originates mostly from organic and inorganic sources such as waste discharges, animal slurries and artificial fertiliser.  High levels of nitrate in drinking water may induce “blue baby” syndrome (methaemaglobinemia).  The nitrate converts to nitrite which reacts with blood haemoglobin thus reducing the availability of the blood to hold oxygen. 

Note 5

Yes

21

Nitrite

0.50

mg/l

Nitrites exist in very low levels principally because the nitrogen will tend to exist in other forms (such as ammonia).  Nitrite is an intermediate in the oxidation of ammonia to nitrate.  Nitrite is associated with methaemaglobinemia as previously discussed. 

Note 5

Yes*

Yes*

22

Pesticides

0.10

mg/l

Pesticides refers to a wide range of chemicals used for the control of pests.  The parametric value is set on a precautionary basis.  Where pesticides are detected the individual pesticide detected must be considered and its toxicology.

Notes 6 and 7

Yes

23

Pesticides – Total

0.50

mg/l

Pesticides refers to a wide range of chemicals used for the control of pests.  The parametric value is set on a precautionary basis.  Where pesticides are detected the individual pesticide detected must be considered and its toxicology.

Note 6 and 8

Yes

24

Polycyclic aromatic hydrocarbons

0.10*

mg/l

Polycyclic Aromatic Hydrocarbons (PAHs) are a group of organic compounds containing 2 or more fused aromatic rings of carbon and hydrogen atoms.  Although there are many compounds in this group, for the purposes of determining compliance with the Drinking Water Regulations only four are considered – benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(ghi)perylene and indeno(1,2,3-cd)pyrene.  They originate from many sources including coal-tar coating of drinking water pipes, soot, vehicle emissions and as combustion products of hydrocarbon fuels.  This group of compounds are widely regarded as carcinogens, though the potency of the different PAHs varies.

Note 9

Yes

25

Selenium

10

mg/l

Selenium originates from the weathering of rocks and soils but is also used in industry as a chemical catalyst.  It is an essential biological requirement though only very small concentrations of selenium are required, above which it is toxic and can cause a variety of illnesses. 

Yes

26

Tetrachloroethene/Trichloroethene

10*

mg/l

Tetrachloroethene and trichloroethene are synthetic solvents used in the dry-cleaning industry and other various industrial and manufacturing processes as well as being used as a degreaser.  It may be carcinogenic but otherwise can have a variety of ill effects. 

Yes

27

Trihalomethanes – Total

100*

mg/l

Trihalomethanes (THMs) are derivatives of the simplest organic compound - methane, CH₄  - in which 3 of the hydrogen atoms are substituted by halogen atoms.  The principal halogens are fluorine (F₂), chlorine (Cl₂), bromine (Br₂) and iodine (I₂), but while many combinations are theoretically possible, the term trihalomethanes is applied to four specific compounds containing only chlorine and/or bromine as the halogen elements.  The four compounds are chloroform (CHCl₃), bromodichloromethane (CHBrCl₂), dibromochloromethane (CHBr₂Cl) and bromoform (CHBr₃). 

Chlorine (or appropriate compounds of it) is undoubtedly the most important chemical used in water treatment in Ireland today, as it has been in the past.  Although it is a highly poisonous gas in its pure form and a powerful oxidising agent, chlorine in very dilute solution is a most effective agent for the disinfection of water.  It is very efficient at destroying those bacteria which originate in human or animal waste and which cause undesirable and dangerous contamination of drinking water. 

As a powerful oxidising agent, chlorine also breaks down the complex and inert organic molecules which are the colouring agents of the water, forming smaller, reactive entities.  These entities react with chlorine (and with bromine derived from the oxidation by chlorine of bromide naturally present) to form the THM compounds, the most abundant of which is chloroform(CHCl₃).  There is thus a fairly straightforward relationship between the degree of colour in the water prior to chlorination and the quantities of THMs present following chlorination.  If colour is present at the point of chlorination, THMs are likely to be formed.

THM compounds are undesirable in drinking water for two reasons.  Firstly, the actual compounds themselves may pose a hazard to the health of the consumer if present in excessive amounts, as chloroform is a suspected carcinogen.  Secondly, the presence of the THM group may be an indicator of the possible presence of other organic by-products of chlorination in trace amounts. The WHO advises that “In controlling trihalomethanes, a multistep treatment system should be used to reduce organic trihalomethane precursors, and primary consideration should be given to ensuring that disinfection is never compromised”.

Note 10

Yes

28

Vinyl chloride

0.50

mg/l

Vinyl chloride can be present in water supplies from the use of unplasticised polyvinyl chloride (uPVC) pipes in water distribution systems.  It is carcinogenic.

Note 1

Indicator Parameters

29

Aluminium

200

mg/l

Aluminium is present in drinking water as a result of its use as aluminium sulphate (a coagulant) in the water treatment process, though can be naturally present in some waters.  Historically, there has been some concern about possible links between aluminium in drinking water and Alzheimer’s disease.  However, the WHO states that:

“On the whole, the positive relationship between aluminium in drinking water and Alzheimer’s disease which was demonstrated in several epidemiological studies, cannot be totally discounted.  However, strong reservations about inferring a causal relationship are warranted in view of the failure of these studies to account for demonstrated confounding factors and for the total aluminium intake from all sources”.

Yes*

Yes*

30

Ammonium

0.30

mg/l

Ammonium in water supplies originates from agricultural and industrial processes, as well as from disinfection with chloramines (a method of disinfection not in use in Ireland ).  Elevated levels of ammonium may arise from intensive agriculture in the catchment of the water source.  Ammonium is therefore an indicator of possible bacterial, sewage and animal waste pollution.  Ammonium in itself is not a health risk but the parametric value serves as a valuable indicator of source pollution. 

Yes

Yes

31

Chloride

250

mg/l

Chloride can originate from natural sources such as saltwater intrusion in coastal sources but can be present in sewage and industrial effluents and thus can be an indicator of pollution from these sources. 

Note 12

Yes

32

Clostridium perfringens

(incl spores)

0

No/100 ml

Clostridium perfringens is a member of the bacterial intestinal flora of humans and therefore serves as an indicator of faecal pollution.  The spores of Clostridium perfringens are particularly resistant to unfavourable conditions in the environment and thus they survive for long periods.  As such they can be useful indicators of water that is intermittently polluted.

Note 13

Yes*

Yes*

33

Colour

Acceptable to consumers and no abnormal change

Colour in water is usually due to the presence of complex organic molecules derived from vegetable (humic) matter such as peat, leaves, branches etc.  While colour, in itself is primarily as aesthetic parameter it may indicate other problems with the water supply particularly where the water is chlorinated.  In such cases the formation of trihalomethanes may occur.

Yes

Yes

34

Conductivity

2500

mS cm^-1 at 20 ⁰C

Conductivity is a measure of the ability of water to conduct an electrical current, therefore conductivity is related to the ionic content of the water. 

Note 12

Yes

Yes

35

Hydrogen ion concentration

³ 6.5 and  £9.5

pH units

pH is a measure of whether a liquid is acid or alkaline.  The pH scale ranges from 0 (very acid) to 14 (very alkaline).  The range of natural pH in freshwaters extends from around 4.5 for acid peaty upland waters to over 10 in waters where there is intense photosynthetic activity by algae.  However, the most frequently encountered range is 6.5 to 8.0.  The control of pH is a critical component of water treatment and distribution, influencing the effectiveness of coagulation, disinfection and the concentration of plumbing materials (such as lead, copper and nickel) in the final product.

Note 12

Yes

Yes

36

Iron

200

mg/l

Iron is an abundant metal found in the Earth’s crust.  It is naturally present in water but can also be present in drinking water from the use of iron coagulants or the corrosion of steel and cast iron pipes during water distribution.  Iron is an essential element in human nutrition.  The WHO (WHO, 2004) states that values of up to 2 mg/l (10 times the parametric value) do not present a hazard to health.  However, at levels less than 2 mg/l but above the parametric value, the colour of water may turn brown, become turbid or may deposit solids on clothes washed in the water or food cooked using water. 

Yes*

Yes*

37

Manganese

50

mg/l

Manganese is an element abundant in the Earth’s crust and is commonly found in groundwater.  In common with iron, the problems associated with levels of manganese above the parametric value are primarily aesthetic, as manganese can cause staining problems.  High levels of manganese also cause objectionable tastes in the water but there are no particular toxicological connotations.  The WHO recommend a guideline value of 0.4 mg/l, which is twice the parametric value in the Regulations.

Yes

38

Odour

Acceptable to consumers and no abnormal change

Yes

Yes

39

Oxidisability

5.0

mg/l 0₂

Oxidisability is a measure of the organic (and other oxidisable) matter present in a water. 

Note 14

40

Sulphate

250

mg/l

Sulphate is naturally occurring and is present in numerous minerals.  The WHO review (WHO, 2004) did not identify a level of sulphate in water that is likely to cause adverse health effects but studies did indicate a laxative effect at concentrations of 1,000 to 1,200 mg/l (i.e., several times higher than the parametric value). 

Note 12

Yes

41

Sodium

200

mg/l

Sodium is an abundant natural constituent of rocks and soils and is always present in natural waters.  Excessive intake can cause hypertension but the primary mode of intake is via food. 

Yes

42

Taste

Acceptable to consumers and no abnormal change

Yes

Yes

43

Colony count 22⁰C

No abnormal change

This is the number of organisms per millilitre when the water is stored at 22⁰C.  The usefulness of this parameter is that sudden or significant changes in the levels of organisms can indicate problems with the water supply.

Yes

44

Coliform bacteria

0

No./100 ml

The coliform bacteria (previously know as Total Coliforms) are a group of organisms that can survive and grow in water.  They are a useful indicator of treatment efficiency and the cleanliness of the distribution mains.  Coliform bacteria can occur in sewage and in natural waters.  Coliform bacteria should not be present in a water that is disinfected and their presence indicates that either disinfection has not been complete, that there is ingress into the water mains in the distribution network or that the sample point is contaminated.

Yes

Yes

45

Total Organic Carbon (TOC)

No abnormal change

This is a measure of the organic carbon in water.  Sudden or significant changes in the level of TOC in the treated water can indicate problems with the water supply.

Note 15

Yes

46

Turbidity

Acceptable to consumers and no abnormal change

The control of turbidity is one of the indicators of the efficiency of treatment at the plant.  Elevated levels of turbidity in the treated water indicate that the treatment process is not operating adequately.  It also provides a good indication of whether the treatment plant is capable of removing Cryptosporidium oocysts.  While the parametric value for turbidity (at the tap) is that the water must be “acceptable to consumers and [there must be] no abnormal change” there is a parametric value for turbidity (for water leaving the treatment plant) of 1.0 NTU.  However, it must be stressed that this value is for visual acceptability of the water.  In practice turbidity levels need to be much lower and should not exceed 0.2 NTU and preferably be below 0.1 NTU to be protective against Cryptosporidium breakthrough in the treatment plant.

Note 16

Yes

Yes

47

Tritium

100

Bq/l

Notes 17 and 19

Yes

48

Total indicative dose

0.10

mSv/year

Notes 18 and 19

Yes