Common contaminants and their sources

The following list is common contaminants you may find in a private supply and the circumstances in which likely to be present:

• Acrylamide can occur if polyacrylamides are used as coagulant aids in water treatment or grouts in borehole/well linings.
• Aluminium can occur if aluminium compounds are used as coagulants. It also may occurs in some surface and ground waters.
• Antimony can potentially leach from domestic plumbing fittings.
• Arsenic can be present in some ground waters.
• Benzene indicates the contamination of raw waters from petrochemicals including petrol or diesel. Benzene can permeate plastic pipes.
• Benzo(a)pyrene can occur after leaching from internal coal tar lining of some pipes.
• Boron can indicate the contamination of surface waters with detergents mainly from sewage effluents.
• Bromate can be present in sodium hypochlorite used to disinfect water, including if this is electrolytically generated hypochlorite. Bromate is also formed if ozone used and water contains bromide, which is in turn indicates contamination from industrial sites.
• Cadmium is leached from galvanised pipes and some domestic plumbing fittings such as plated taps.
• Chloride indicates of saline intrusion in coastal areas. Chloride may also be present if a water softener is installed or it may indicate sewage pollution of surface water.
• Chromium is leached from some domestic plumbing fittings such as chrome plated plastic taps.
• Clostridium perfringens (including spores) indicates the contamination of raw waters from sewage effluents and animal waste.
• Copper is leached from pipes and plumbing fittings. Low pH and low or high alkalinity increases copper leaching.
• Cyanide may indicate contamination of raw waters from industry (e.g. metal finishing, wood preservatives).
• 1,2 dichloroethane is a volatile solvent used in manufacture of vinyl chloride and other processes. It can contaminate and persist in ground water.
• Enterococci indicates contamination of raw waters from sewage, sewage effluents and animal waste.
• Epichlorohydrin may occur is polyamines are used as coagulant aids in water treatment, if epoxy resins are used to line pipes and tanks, or if an ion exchange unit is installed.
• Fluoride is naturally present in some ground waters.
• Iron may be present if iron compounds as coagulants in water treatment. Iron also naturally occurs in some surface water and ground waters. It may also indicate corrosion of iron distribution mains.
• Lead is leached from lead pipes in distribution and domestic plumbing or from lead soldered copper pipes. Low pH and low or high alkalinity increases lead leaching. Lead is present naturally in some ground waters.
• Manganese is present in some greensand filtration materials. It occurs in some surface water and ground waters.
• Mercury may indicate contamination from mercury thermometers and float valves.
• Nickel may indicate leaching from some domestic plumbing fittings (e.g. plated taps).
• Nitrate indicates contamination of surface and ground waters from fertilisers, animal wastes or sewage effluents.
• Nitrite indicates contamination of raw waters. The use of chloramination as a residual disinfectant or use of chlorine as disinfectant when ammonium ions present.
• Pesticides indicate contamination of raw waters from use in agriculture, forestry, roads, railways etc.
• Polycyclic aromatic hydrocarbons (PAH) can indicate leaching from internal coal tar lining of some distribution
• pipes or contamination from industry.
• Selenium may occur naturally in some raw waters.
• Sodium is present in raw waters but usually below health-based standards. Sodium can be introduced by water softeners and treatment chemicals such as sodium hypochlorite for disinfection, or through saline intrusion of ground waters in coastal areas.
• Sulphate occurs in some raw waters, but usual below the health-based standard.
• Tetrachloroethene and Trichloroethene contamination of some ground waters can arise from use of these volatile solvents in dry cleaning and metal finishing.
• Tetrachloromethane contamination of some ground waters from use of this volatile solvent in metal finishing and other industries.
• Radioactivity can indicate contamination of raw waters from natural or manmade radioactive compounds.
• Trihalomethanes are formed by reaction of organic matter in raw water with chlorine compounds used as disinfectants.
• Tritium is a by-product of nuclear explosions and nuclear industry.
• Vinyl chloride is used for making PVC. It can indicate leaching from unplasticised PVC pipes used in distribution or domestic plumbing.