Water quality standards explained

Parameter

What it means

MAC/PCV

1, 2 Dichloroethane

1, 2 Dichloroethane is a solvent that may be found in groundwater in the vicinity of industrial sites

3μg/l

2,3,6 TBA

2,3,6 TBA is one of a large group of organic compounds used as a weedkiller, insecticide or fungicide. Water sources may contain traces of pesticides as a result of agricultural and non-agricultural use. Monitoring varies according to the risk

0.1μg/l

2,4,5 –T

2,4,5 –T is one of a large group of organic compounds used as a weedkiller, insecticide or fungicide. Water sources may contain traces of pesticides as a result of agricultural and non-agricultural use. Monitoring varies according to the risk

0.1μg/l

2,4 - D

2,4 - D is one of a large group of organic compounds used as a weedkiller, insecticide or fungicide. Water sources may contain traces of pesticides as a result of agricultural and non-agricultural use. Monitoring varies according to the risk

0.1μg/l

Aldicarb

Aldicarb is one of a large group of organic compounds used as a weedkiller, insecticide or fungicide. Water sources may contain traces of pesticides as a result of agricultural and non-agricultural use. Monitoring varies according to the risk

0.1μg/l

Alkalinity

Alkalinity is the measure of the ability of the water to neutralise acids; usually high in groundwater

No MAC

Aluminium

Aluminium occurs naturally. Aluminium compounds are not used in treatment processes by CWC

200μg/l

Ammonium

Ammonium occurs naturally. It does not cause health problems and it can be controlled or removed by treatment

0.5mg/l

Antimony

Antimony is rarely found in water except in areas of heavy industry

5μg/l

Arsenic

Arsenic is rarely found in water except in areas of heavy industry

10μg/l

Atrazine

Atrazine is one of a large group of organic compounds used as a weedkiller, insecticide or fungicide. Water sources may contain traces of pesticides as a result of agricultural and non-agricultural use. Monitoring varies according to the risk

0.1μg/l

Benzene

Benzene is rarely found in water. Used in petrol, contamination can occur from spillages in the vicinity of plastic pipes

1μg/l

Benzo (a) pyrene

Benzo (a) pyrene is one of a group of compounds known as polycyclic aromatic hydrocarbons (PAHs). They can occur in drinking water from coal tar pitch linings of some iron mains

100ng/l

Boron

Boron is rarely found in water except in areas of heavy industry

1 mg/l

Bromate

Bromate is not usually found in ground water but can arise as a by-product of disinfection processes

10μg/l

Cadmium

Cadmium is rarely found in water except in areas of heavy industry

5μg/l

Carbaryl

Carbaryl is one of a large group of organic compounds used as a weedkiller, insecticide or fungicide. Water sources may contain traces of pesticides as a result of agricultural and non-agricultural use. Monitoring varies according to the risk

0.1μg/l

Carbetamide

Carbetamide is one of a large group of organic compounds used as a weedkiller, insecticide or fungicide. Water sources may contain traces of pesticides as a result of agricultural and non-agricultural use. Monitoring varies according to the risk

0.1μg/l

Chlorbufam

Chlorbufam is one of a large group of organic compounds used as a weedkiller, insecticide or fungicide. Water sources may contain traces of pesticides as a result of agricultural and non-agricultural use. Monitoring varies according to the risk

0.1μg/l

Chloride

Chloride occurs naturally from the rocks through which it passes, is found in common salt and is not harmful to health

250mg/l

Chlorine residual

Chlorine is added to water to kill bacteria. Some is used up in the disinfection process, the residual is present to maintain the quality of the water to distribution

Chlorpropham

Chlorpropham is one of a large group of organic compounds used as a weedkiller, insecticide or fungicide. Water sources may contain traces of pesticides as a result of agricultural and non-agricultural use. Monitoring varies according to the risk

0.1μg/l

Chlortoluron

Chlortoluron is one of a large group of organic compounds used as a weedkiller, insecticide or fungicide. Water sources may contain traces of pesticides as a result of agricultural and non-agricultural use. Monitoring varies according to the risk

0.1μg/l

Chromium

Chromium is rarely found in water except in areas of heavy industry

50μg/l

Clostridia Perfringens

Clostridia perfringen is a spore-forming bacterium present in the gut of warm-blooded animals. Its presence in drinking water indicates historic contamination requiring investigation

0 per 100ml

Coliform Bacteria

Coliform bacteria are widely distributed in the environment and sometimes in untreated water. Disinfection removes them. Their presence in treated water requires immediate investigation

0 per 100ml

Colony Counts

Colony counts are harmless bacteria present in foods like yogurt and treated water. Numbers and groupings are monitored to give an overall picture

Significant differences are investigated

Colour

This is an aesthetic requirement. Water should be clear and bright, but may occasionally show a reddish or yellowish tint caused by iron from old iron mains. It is not harmful to health

20 mg/l on Platignum / Cobalt (Pt/Co) scale

Conductivity

Conductivity is the ability of water to conduct an electric current. It is used as a measure of natural inorganic substances in the water

2500 μS/cm

Copper

Copper is a metal, traces of which may be found in water from internal plumbing and which may cause staining of sanitary ware

2mg/l

Cryptosporidium

Cryptosporidium is a parasite that can cause severe gastroenteritis

< 1 oocyst / 10 litres

Cyanide

Cyanide is rarely found in water except in areas of heavy industry

50μg/l

Dicamba

Dicamba is one of a large group of organic compounds used as a weedkiller, insecticide or fungicide. Water sources may contain traces of pesticides as a result of agricultural and non-agricultural use. Monitoring varies according to the risk

0.1μg/l

Dichlorprop

Dichlorprop is one of a large group of organic compounds used as a weedkiller, insecticide or fungicide. Water sources may contain traces of pesticides as a result of agricultural and non-agricultural use. Monitoring varies according to the risk

0.1μg/l

Diuron

Diuron is one of a large group of organic compounds used as a weedkiller, insecticide or fungicide. Water sources may contain traces of pesticides as a result of agricultural and non-agricultural use. Monitoring varies according to the risk

0.1μg/l

E.P.T.C

E.P.T.C. is one of a large group of organic compounds used as a weedkiller, insecticide or fungicide. Water sources may contain traces of pesticides as a result of agricultural and non-agricultural use. Monitoring varies according to the risk

0.1μg/l

Enterococci or Faecal Streptococci

Enterococcus is a bacterium present in the gut of warm-blooded animals. In water it is an indicator of faecal contamination. Immediate action is required to identify and remove the source of any contamination found

0 per 100ml

Escherichia (Faecal) Coliforms (E.Coli)

E. Coliform is a bacterium present in the gut of warm-blooded animals. In water it is an indicator of faecal contamination. Immediate action is required to identify and remove the source of any contamination found

0 per 100ml

Fluoride

Fluoride occurs naturally in groundwater. None is added by CWC

1.5mg/l

Hydrogen ion (pH)

pH gives an indication of the acidity of the water

6.5 – 9.5

Iron

Iron is found naturally in some ground water. It can occur from old iron mains or domestic plumbing. It does not cause health problems but it can give the water a reddish or yellowish tinge.

200μg/l

Isoproturon

Isoproturon is one of a large group of organic compounds used as a weedkiller, insecticide or fungicide. Water sources may contain traces of pesticides as a result of agricultural and non-agricultural use. Monitoring varies according to the risk

0.1μg/l

Lead

There is little lead in the water supplied but lead can leach from lead domestic plumbing and pipework.

25μg/l

(10μg/l from 2013)

Linuron

Linuron is one of a large group of organic compounds used as a weedkiller, insecticide or fungicide. Water sources may contain traces of pesticides as a result of agricultural and non-agricultural use. Monitoring varies according to the risk

0.1μg/l

Manganese

Manganese occurs naturally and can cause staining to some surfaces

50μg/l

MCPA

MCPA is one of a large group of organic compounds used as a weedkiller, insecticide or fungicide. Water sources may contain traces of pesticides as a result of agricultural and non-agricultural use. Monitoring varies according to the risk

0.1μg/l

MCPB

MCPB is one of a large group of organic compounds used as a weedkiller, insecticide or fungicide. Water sources may contain traces of pesticides as a result of agricultural and non-agricultural use. Monitoring varies according to the risk

0.1μg/l

MCPP(Mecoprop)

Mecoprop is one of a large group of organic compounds used as a weedkiller, insecticide or fungicide. Water sources may contain traces of pesticides as a result of agricultural and non-agricultural use. Monitoring varies according to the risk

0.1μg/l

Mercury

Mercury is rarely found in water except in areas of heavy industry

1μg/l

Methiocarb

Methiocarb is one of a large group of organic compounds used as a weedkiller, insecticide or fungicide. Water sources may contain traces of pesticides as a result of agricultural and non-agricultural use. Monitoring varies according to the risk

0.1μg/l

Nickel

Nickel is rarely found in water except in areas of heavy industry

20μg/l

Nitrate

Nitrate occurs naturally in all waters especially where agricultural fertilisers have been used

50mg/l

Nitrite

Nitrite is sometimes produced as a by-product of disinfection processes

0.5mg/l

Odour

Treated water may smell of chlorine as a result of disinfection processes. Samples are evaluated by a panel of analysts at the laboratory

Significant odours are investigated

Perfluorooctane sulformate (PFOs)

Perfluorooctane sulformate (PFOs) is now prohibited but it was used in industry, fire-fighting foams, hydraulic fluids, protective coatings and cleaning products. Monitoring varies according to risk.

300ng/l

Perfluorooctanoic acid (PFOA)

Perfluorooctanoic acid (PFOA) is being phased out but is still used on the production of fluoropolymers used in electronics, textiles and non-stick cook wear. Monitoring varies according to risk

300ng/l

Phosphorus

Ortho-phosphoric acid is added to water to prevent lead leaching from lead domestic plumbing and pipework

No MAC

Pirimicarb

Pirimicarb is one of a large group of organic compounds used as a weedkiller, insecticide or fungicide. Water sources may contain traces of pesticides as a result of agricultural and non-agricultural use. Monitoring varies according to the risk

0.1μg/l

Polycyclic aromatic hydrocarbons (PAH)

This is a group of compounds that can occur in drinking water from the coal tar pitch linings of certain iron mains. Benzo (b) fluoranthene

Benzo (k) fluoranthene

Benzo (ghi) perylene

Indeno(1,2,3-cd)pyrene

Sum of compounds 0.1μg/l

Prometryne

Prometryne is one of a large group of organic compounds used as a weedkiller, insecticide or fungicide. Water sources may contain traces of pesticides as a result of agricultural and non-agricultural use. Monitoring varies according to the risk

0.1μg/l

Propazine

Propazine is one of a large group of organic compounds used as a weedkiller, insecticide or fungicide. Water sources may contain traces of pesticides as a result of agricultural and non-agricultural use. Monitoring varies according to the risk

0.1μg/l

Propham

Propham is one of a large group of organic compounds used as a weedkiller, insecticide or fungicide. Water sources may contain traces of pesticides as a result of agricultural and non-agricultural use. Monitoring varies according to the risk

0.1μg/l

Selenium

Selenium is a an essential element, naturally occurring

10μg/l

Simazine

Simazine is one of a large group of organic compounds used as a weedkiller, insecticide or fungicide. Water sources may contain traces of pesticides as a result of agricultural and non-agricultural use. Monitoring varies according to the risk

0.1μg/l

Sodium

Sodium is naturally occurring, is a component of common salt and is a by-product of softening. CWC does not soften the water

200mg/l

Sulphate

Sulphate occurs naturally in water and comes from mineral deposits

250mg/l

Taste

Water supplied by CWC should have no taste but water can pick up a taste from the materials through which it passes. Samples are evaluated by a panel of analysts at the laboratory

Significant tastes are investigated

Terbutryne

Terbutryne is one of a large group of organic compounds used as a weedkiller, insecticide or fungicide. Water sources may contain traces of pesticides as a result of agricultural and non-agricultural use. Monitoring varies according to the risk

0.1μg/l

Tetrachloroethene and Trichloroethene

Tetrachloroethene and Trichloroethene are solvents that may occur in groundwater in the vicinity of industry

Sum of substances 10μg/l

Tetrachloromethane

Tetrachloromethane is a solvent that may occur in groundwater in the vicinity of industrial sites

3μg/l

Trietazine

Trietazine is one of a large group of organic compounds used as a weedkiller, insecticide or fungicide. Water sources may contain traces of pesticides as a result of agricultural and non-agricultural use. Monitoring varies according to the risk

0.1μg/l

Total Indicative Dose (TID)

TID is a measure of the effective dose of radiation the body will receive from consumption of the water. It is calculated when values of gross alpha and gross beta are exceeded

0.1mSv/year

Total Organic Carbon

Total Organic Carbon represents the total amount of organic matter, naturally occurring carbon, in the water

No abnormal change

Total Pesticides

Sum of the concentrations of the individual pesticides detected and quantified in the monitoring process

0.5μg/l

Tri-allate

Tri-allate is one of a large group of organic compounds used as a weedkiller, insecticide or fungicide. Water sources may contain traces of pesticides as a result of agricultural and non-agricultural use. Monitoring varies according to the risk

0.1μg/l

Trihalomethanes

Trihalomethanes are a group of compounds formed during disinfection by a reaction between chlorine and naturally occurring organic matter

Chloroform

Bromoform

Dibromochloromethane

Bromodichloromethane

Sum of compounds 100μg/l

Tritium

Tritium is a radioactive isotope of hydrogen

100Bq/l

Turbidity

Turbidity is a measure of the cloudiness of water. This may be caused by air bubbles and is not harmful. Disturbance of sediment in the water mains can also cause turbudity

4 Formazin units

Zinc

Traces of this metal may be found in water from internal plumbing and can cause staining of sanitary ware

No PCV