UK Department of the Environment, Food and Rural Affairs

Drinking Water 2001

A report by the Chief Inspector
Drinking Water Inspectorate

Annex 3 - Definitions and Glossary of Terms

These definitions will assist the understanding of the Report where technical terms may have been used.

Aesthetic

associated with the senses of taste, smell and sight

After-growth
the growth of micro-organisms within distribution systems

Alkali
a solution containing an excess of free hydroxyl ions, with a pH greater than seven

Aquifer
water-containing underground strata

Authorities
the Secretary of State for the Environment, Food and Rural Affairs, the National Assembly for Wales, or the Welsh Assembly Government as the context may require

Badenoch Reports
the first (1990) and second (1995) reports of the Group of Experts on Cryptosporidium in Water Supplies

Biocidal
having the property of inactivating pathogens

Biofilm
naturally-occurring growth of micro-organisms on surfaces inside water mains

Bouchier Report
the third (1998) report of the Group of Experts on Cryptosporidium in Water Supplies

Bulk supply
water supplied in bulk, usually in treated form, from one water company to another

Chloramination
an alternative form of disinfectant based on chlorine and ammonia which provides a longer lasting residual in the distribution system compared to free chlorine

Coagulation
the process of aggregating colloidal and fine particulate matter into a settleable material

Coliforms
a group of generally harmless bacteria which may be faecal or environmental in origin

Compound
a compound consists of two or more elements in chemical combination

Compliance assessment
a comparison made by the Inspectorate of data gathered by water companies against standards and other regulatory requirements

Compliance programme
a programme of works required as part of an undertaking

Contravention
a breach of a regulatory requirement

Crohn's Disease
Crohn's disease is an inflammation of the bowel

Cryptosporidium
a protozoan parasite. Cryptosporidosis is the associated illness

Determination
an analysis for a specific parameter

Distribution systems
a water company's network of mains, pipes, pumping stations and service reservoirs through which treated water is conveyed to consumers

EC Drinking Water Directive
Council Directive 80/778/EEC relating to the quality of water intended for human consumption. (Replaced by Council Directive 98/83/EC in December 1998 - the 'New Directive')

Enforcement action
the means, as set out in the Water Act 1989 and consolidated into the Water Industry Act 1991, by which the Secretary of State requires a water company to comply with certain regulatory requirements

Epidemiology
a process of studying the distribution of cases of disease within a population in relation to exposure to possible sources of the infection, with a view to establishing the actual source of the infection

Epoxy resin relining
a rehabilitation process in which a cleaned section of iron water main is sprayed with a mixture of epoxy resin and hardener to produce a thin but strong coating of material on the inside of the main

Exceedence
synonym for contravention or breach (see above)

Faecal coliforms
a sub-group of coliforms, almost exclusively faecal in origin

Filtration
the separation of suspended particulate matter from a fluid

Giardia
a protozoan parasite

Granular Activated Carbon
an adsorbent filtration media used to remove trace organic compounds from water

Groundwater
water from aquifers or other underground sources

Guidance Document
'Guidance on Safeguarding the Quality of Public Water Supplies'. HMSO 1989 (ISBN 0 11 752262 7)

Improvement programmes
improvement works, associated with undertakings or conditions of Regulation 4 relaxations

Incident
an event affecting or threatening to affect drinking water quality

Indicator organism
an organism which indicates the presence of contamination and hence the possible presence of pathogens

Key parameters
15 parameters chosen to indicate quality of water in supply zones and to allow comparisons to be made between companies

Legal requirements
the requirements as specified in the Water Act 1989, now consolidated into the Water Industry Act 1991, and the Regulations made under the Acts

Mean zonal percentage compliance
see zonal percentage compliance

Microbiological
associated with the study of microbes

Mycobacterium Avium Complex (MAC)
a group of bacteria responsible for pulmonary and non-pulmonary infections, particularly in the immuno-compromised

Mycobacterium Paratuberculosis (MAP)
species of the Mycobacterium Avium Complex (MAC) group of organisms that causes Johne's disease in cattle.

m3/d
cubic metre per day

mg/l
milligram per litre (one thousandth of a gram per litre)

Ml/d
megalitre per day (one Ml/d is equivalent to 1,000 m³/d, or to 220,000 gallon/d)

µg/l
microgram per litre (one millionth of a gram per litre)

ng/l
nanogram per litre (one billionth of a gram per litre)

New Regulations
the Water Supply (Water Quality) Regulations 2000 (also referred to as the '2000 Regulations')

Notice of Intention to make a Final Order
a necessary precursor to the issue of an Enforcement Order which must be advertised with a minimum of 28 days being allowed for representations or objections to the proposed Order

Oocyst
the resistant form in which Cryptosporidium occurs in the environment, and which is capable of causing infection

Operational Guidelines and Code of Practice (OGCP)
'In situ Epoxy Resin Lining - Operational Guidelines and Code of Practice. A source document for the Water Mains Rehabilitation Manual'. I C Warren. WRc 1989

Operational performance index
the average of the mean zonal compliance for each of the six parameters most reflecting the operation and maintenance of treatment works and distribution systems

Outbreak Control Team (OCT)
a team set up to investigate possible waterborne outbreaks of cryptosporidiosis, comprising members of the medical profession, as well as representatives of relevant local authorities and water companies

Overall quality index
the average of the mean zonal compliance for each of the 15 key parameters

Ozone process
the application of ozone gas in drinking water treatment

Parameters
The substances, organisms and properties listed in Schedule 2 and Regulation 3 of the Regulations. Parameter definitions can be found in the Introduction to Part 2 of this report.

Pathogen
an organism which can cause disease

PCV
see 'Prescribed concentration or value'

Pesticides
any fungicide, herbicide or insecticide or related product (excluding medicines) used

for the control of pests or diseases

pH value
a measure of the acidity or basicity related to the concentration of the hydrogen ion

Plumbosolvency
the tendency for lead to dissolve in water

Polycyclic aromatic hydrocarbons (PAH)
the presence of PAHs in drinking water is usually associated with pre-1970s distribution mains that were lined with coal tar to prevent corrosion. The concentrations found are not of significance to health.

Pre- and post-renovation assessment (PPRA)
a programme of assessment before and after mains renovation to demonstrate justification for the work, and the improvements achieved by the renovation

Prescribed concentration or value (PCV)
the numerical value assigned to water quality standards defining the maximal or minimal legal concentration or value of a parameter. In certain circumstances, the PCV may be authorised by the Secretary of State under Regulation 4 to be relaxed to a specified extent - see 'Relaxation'

Principles of Water Supply Hygiene and Technical Guidance Notes
a booklet identifying principles to be considered when developing procedures for safeguarding water supplies against contamination and guidance on development of such procedures - published by Water UK, October 1998

Private supplies
water taken from private sources or supplied by non-licensed suppliers; supplies of water provided otherwise than by a statutorily appointed water undertaker

Protozoan Parasites
a single cell organism that can only survive by infecting a host

Public Record
the information made available to the public as required by Regulations 29 and 30

Public supplies
water supplied by a company licensed for that purpose

Regulations
the Water Supply (Water Quality) Regulations 1989, as amended, made under the Act or, in the case of private water supplies, the Private Water Supplies Regulations 1991

Regulatory requirements
see 'Legal requirements'

Relaxation
a relaxation of the standards according to Regulations 4 and 5 - subject in most cases to the completion of improvement works - in emergencies or as a result of exceptional meteorological conditions or by reason of the nature and structure of the ground from which the supply emanates

Remedial action
action taken to improve a situation

Secretary of State
the Secretary of State for the Environment, Food and Rural Affairs

Service reservoir
a water tower, tank or other reservoir used for the storage of treated water within the distribution system

Sodium Chloride
a chemical commonly known as table salt

Springs
groundwater appearing at the surface at the outcrop of the junction of a permeable with an impermeable stratum

Standards
the prescribed concentrations or values listed in Schedule 2, Tables A to E and Regulation 3 of the Regulations

Steroid
a fat-soluble organic compound found in living organisms

Supply point
a point other than a consumer's tap authorised for the taking of samples for compliance with the Regulations

Surface water
water from rivers, impounding reservoirs or other surface water source

Technical audit
the means of checking that water companies are complying with their statutory obligations

Time of supply
the moment when water passes from the water company's pipework into a consumer's pipework

Trihalomethanes (TMHs)
A group of compounds, formed during the disinfection process by the reaction between chlorine and naturally occurring organic substances present in water. The detection of THMs is indicative of the likely presence of other disinfection by products.

Toxicology
the study of the health effects of substances

Treated water
water treated for use for domestic purposes as defined in the Regulations

Undertaking
a legally binding programme of work to take appropriate steps to secure or restore compliance with regulatory duties; given by a water company to the Secretary of State for the purposes of section 19(1)(b) of the Water Industry Act 1991

Water supply zone
a pre-defined area of supply for establishing sampling frequencies, compliance with standards and information to be made publicly available

Wholesome/Wholesomeness
a concept of water quality which is defined by reference to standards and other requirements set out in the Regulations

WRc
Water Research Centre (1989) Plc and/or, as the context may require, its predecessor body

Zonal percentage compliance
the percentage of results for a specific parameter which complied with the PCV - the mean zonal percentage compliance is the average of the zonal percentage compliances of every one of a company's zones

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Drinking Water Inspectorate,
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Telephone : 020 7944 5956 - Facsimile : 020 7944 5969
E-mail: dwi.enquiries@defra.gsi.gov.uk

Published 10 July 2002
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Aesthetic	associated with the senses of taste, smell and sight
After-growth	the growth of micro-organisms within distribution systems
Alkali	a solution containing an excess of free hydroxyl ions, with a pH greater than seven
Aquifer	water-containing underground strata
Authorities	the Secretary of State for the Environment, Food and Rural Affairs, the National Assembly for Wales, or the Welsh Assembly Government as the context may require
Badenoch Reports	the first (1990) and second (1995) reports of the Group of Experts on Cryptosporidium in Water Supplies
Biocidal	having the property of inactivating pathogens
Biofilm	naturally-occurring growth of micro-organisms on surfaces inside water mains
Bouchier Report	the third (1998) report of the Group of Experts on Cryptosporidium in Water Supplies
Bulk supply	water supplied in bulk, usually in treated form, from one water company to another
Chloramination	an alternative form of disinfectant based on chlorine and ammonia which provides a longer lasting residual in the distribution system compared to free chlorine
Coagulation	the process of aggregating colloidal and fine particulate matter into a settleable material
Coliforms	a group of generally harmless bacteria which may be faecal or environmental in origin
Compound	a compound consists of two or more elements in chemical combination
Compliance assessment	a comparison made by the Inspectorate of data gathered by water companies against standards and other regulatory requirements
Compliance programme	a programme of works required as part of an undertaking
Contravention	a breach of a regulatory requirement
Crohn's Disease	Crohn's disease is an inflammation of the bowel
*Cryptosporidium*	a protozoan parasite. Cryptosporidosis is the associated illness
Determination	an analysis for a specific parameter
Distribution systems	a water company's network of mains, pipes, pumping stations and service reservoirs through which treated water is conveyed to consumers
EC Drinking Water Directive	Council Directive 80/778/EEC relating to the quality of water intended for human consumption. (Replaced by Council Directive 98/83/EC in December 1998 - the 'New Directive')
Enforcement action	the means, as set out in the Water Act 1989 and consolidated into the Water Industry Act 1991, by which the Secretary of State requires a water company to comply with certain regulatory requirements
Epidemiology	a process of studying the distribution of cases of disease within a population in relation to exposure to possible sources of the infection, with a view to establishing the actual source of the infection
Epoxy resin relining	a rehabilitation process in which a cleaned section of iron water main is sprayed with a mixture of epoxy resin and hardener to produce a thin but strong coating of material on the inside of the main
Exceedence	synonym for contravention or breach (see above)
Faecal coliforms	a sub-group of coliforms, almost exclusively faecal in origin
Filtration	the separation of suspended particulate matter from a fluid
Giardia	a protozoan parasite
Granular Activated Carbon	an adsorbent filtration media used to remove trace organic compounds from water
Groundwater	water from aquifers or other underground sources
Guidance Document	'Guidance on Safeguarding the Quality of Public Water Supplies'. HMSO 1989 (ISBN 0 11 752262 7)
Improvement programmes	improvement works, associated with undertakings or conditions of Regulation 4 relaxations
Incident	an event affecting or threatening to affect drinking water quality
Indicator organism	an organism which indicates the presence of contamination and hence the possible presence of pathogens
Key parameters	15 parameters chosen to indicate quality of water in supply zones and to allow comparisons to be made between companies
Legal requirements	the requirements as specified in the Water Act 1989, now consolidated into the Water Industry Act 1991, and the Regulations made under the Acts
Mean zonal percentage compliance	see zonal percentage compliance
Microbiological	associated with the study of microbes
*Mycobacterium Avium Complex (MAC)*	a group of bacteria responsible for pulmonary and non-pulmonary infections, particularly in the immuno-compromised
*Mycobacterium Paratuberculosis (MAP)*	species of the Mycobacterium Avium Complex (MAC) group of organisms that causes Johne's disease in cattle.
m3/d	cubic metre per day
mg/l	milligram per litre (one thousandth of a gram per litre)
Ml/d	megalitre per day (one Ml/d is equivalent to 1,000 m³/d, or to 220,000 gallon/d)
µg/l	microgram per litre (one millionth of a gram per litre)
ng/l	nanogram per litre (one billionth of a gram per litre)
New Regulations	the Water Supply (Water Quality) Regulations 2000 (also referred to as the '2000 Regulations')
Notice of Intention to make a Final Order	a necessary precursor to the issue of an Enforcement Order which must be advertised with a minimum of 28 days being allowed for representations or objections to the proposed Order
Oocyst	the resistant form in which Cryptosporidium occurs in the environment, and which is capable of causing infection
Operational Guidelines and Code of Practice (OGCP)	'In situ Epoxy Resin Lining - Operational Guidelines and Code of Practice. A source document for the Water Mains Rehabilitation Manual'. I C Warren. WRc 1989
Operational performance index	the average of the mean zonal compliance for each of the six parameters most reflecting the operation and maintenance of treatment works and distribution systems
Outbreak Control Team (OCT)	a team set up to investigate possible waterborne outbreaks of cryptosporidiosis, comprising members of the medical profession, as well as representatives of relevant local authorities and water companies
Overall quality index	the average of the mean zonal compliance for each of the 15 key parameters
Ozone process	the application of ozone gas in drinking water treatment
Parameters	The substances, organisms and properties listed in Schedule 2 and Regulation 3 of the Regulations. Parameter definitions can be found in the Introduction to Part 2 of this report.
Pathogen	an organism which can cause disease
PCV	see 'Prescribed concentration or value'
Pesticides	any fungicide, herbicide or insecticide or related product (excluding medicines) used
	for the control of pests or diseases
pH value	a measure of the acidity or basicity related to the concentration of the hydrogen ion
Plumbosolvency	the tendency for lead to dissolve in water
Polycyclic aromatic hydrocarbons (PAH)	the presence of PAHs in drinking water is usually associated with pre-1970s distribution mains that were lined with coal tar to prevent corrosion. The concentrations found are not of significance to health.
Pre- and post-renovation assessment (PPRA)	a programme of assessment before and after mains renovation to demonstrate justification for the work, and the improvements achieved by the renovation
Prescribed concentration or value (PCV)	the numerical value assigned to water quality standards defining the maximal or minimal legal concentration or value of a parameter. In certain circumstances, the PCV may be authorised by the Secretary of State under Regulation 4 to be relaxed to a specified extent - see 'Relaxation'
Principles of Water Supply Hygiene and Technical Guidance Notes	a booklet identifying principles to be considered when developing procedures for safeguarding water supplies against contamination and guidance on development of such procedures - published by Water UK, October 1998
Private supplies	water taken from private sources or supplied by non-licensed suppliers; supplies of water provided otherwise than by a statutorily appointed water undertaker
Protozoan Parasites	a single cell organism that can only survive by infecting a host
Public Record	the information made available to the public as required by Regulations 29 and 30
Public supplies	water supplied by a company licensed for that purpose
Regulations	the Water Supply (Water Quality) Regulations 1989, as amended, made under the Act or, in the case of private water supplies, the Private Water Supplies Regulations 1991
Regulatory requirements	see 'Legal requirements'
Relaxation	a relaxation of the standards according to Regulations 4 and 5 - subject in most cases to the completion of improvement works - in emergencies or as a result of exceptional meteorological conditions or by reason of the nature and structure of the ground from which the supply emanates
Remedial action	action taken to improve a situation
Secretary of State	the Secretary of State for the Environment, Food and Rural Affairs
Service reservoir	a water tower, tank or other reservoir used for the storage of treated water within the distribution system
Sodium Chloride	a chemical commonly known as table salt
Springs	groundwater appearing at the surface at the outcrop of the junction of a permeable with an impermeable stratum
Standards	the prescribed concentrations or values listed in Schedule 2, Tables A to E and Regulation 3 of the Regulations
Steroid	a fat-soluble organic compound found in living organisms
Supply point	a point other than a consumer's tap authorised for the taking of samples for compliance with the Regulations
Surface water	water from rivers, impounding reservoirs or other surface water source
Technical audit	the means of checking that water companies are complying with their statutory obligations
Time of supply	the moment when water passes from the water company's pipework into a consumer's pipework
Trihalomethanes (TMHs)	A group of compounds, formed during the disinfection process by the reaction between chlorine and naturally occurring organic substances present in water. The detection of THMs is indicative of the likely presence of other disinfection by products.
Toxicology	the study of the health effects of substances
Treated water	water treated for use for domestic purposes as defined in the Regulations
Undertaking	a legally binding programme of work to take appropriate steps to secure or restore compliance with regulatory duties; given by a water company to the Secretary of State for the purposes of section 19(1)(b) of the Water Industry Act 1991
Water supply zone	a pre-defined area of supply for establishing sampling frequencies, compliance with standards and information to be made publicly available
Wholesome/Wholesomeness	a concept of water quality which is defined by reference to standards and other requirements set out in the Regulations
WRc	Water Research Centre (1989) Plc and/or, as the context may require, its predecessor body
Zonal percentage compliance	the percentage of results for a specific parameter which complied with the PCV - the mean zonal percentage compliance is the average of the zonal percentage compliances of every one of a company's zones

Drinking Water 2001

A report by the Chief InspectorDrinking Water Inspectorate

Annex 3 - Definitions and Glossary of Terms

A report by the Chief Inspector
Drinking Water Inspectorate