WORLD HEALTH ORGANIZATION
ORGANISATION MONDIALE DE LA SANTE
REGIONAL OFFICE FOR THE WESTERN PACIFIC BUREAU R~GIONAL OU PACIFIQUE OCCIDENTAL
REGIONAL COMMITTEE Thirty-fifth session Suva 5-l 1 September 1984 Provisional agenda item 16
WPR/RC35 /12 10 May 1984
ORIGINAL: ENGLISH
WHO GUIDELINES FOR DRINKING-WATER QUALITY
This item has been placed on the provisional agenda of the Regional Cornmittee at the request of the Government of New Zealand. The Regional Committee, at its thirty-fourth session, adopted resolution WPR/RC34.R4 on the International Drinking-Water Supply and Sanitation Decade, calling upon Member States to revise existing plans and programmes as necessary in order to provide full coverage of the population. To support national plans in the provision of safe drinking water, WHO has prepared the Guidelines for drinking-water quality as a 1 important mechanism for the development or revision of n ltional standards in support of monitoring, surveillance and cJntrol programmes. Following a review of the development of these guidelines, a brief outline of the Guidelines for drinking-water quality (3-volumes) is presented, together with recommendations which the Regional Committee may wish to consider.
WPR/RC35/12 page 2
I. INTRODUCTION In the field of health promotion, WHO has given high priority to the provision of safe drinking water and adequate sanitation. With a view to facilitating the application of control measures to ensure the safety of drinking water, WHO published the first International standards for drinking-water in 1958. A second edition appeared in 1963 and a third edition was published in 1971. The United Nations Water Conference, held at Mar del Plata, Argentina, in 1977, designated the period 1981-1990 as the International Drinking-Water Supply and Sanitation Decade. The United Nations General Assembly launched the Decade in November 1980, the aim being to provide all people and particularly the rural and underprivileged periurban areas with adequate supplies of safe water and sanitation by 1990, if possible. The Thirty-sixth World Health Assembly, by its resolution WHA 36.13, emphasized the importance of safe drinking water and adequate sanitation services as an essential component of primary health care and called upon Member States to support the national programmes. One of the important elements of the national programmes is the assurance of safe drinking-water supplies through the development of effective monitoring, surveillance and control activities at all levels of operational plans. The adoption of rules and regulations covering drinking-water quality plays a critical role in these programmes. A national monitoring, surveillance and control programme needs to be implemented with a view to criteria development and the subsequent establishment of standards. Since 1971, when the International standards for drinking-water was last revised, a considerable body of new knowledge and experience has been acquired with respect to contaminants in drinking-water supplies and their effects on health. This is particularly true with ··egard to the many toxic and hazardous substances manufactured and subsequent! r released in the environment. It was decided that another revision of the International standards was necessary in order to incorporate new information and to facilitate attainment of the goals of the Decade with respect to safety of drinking-water supplies.
2. DEVELOPMENT OF THE GUIDELINES The principal approach in developing the WHO Guidelines was governed by the recognition that water for human consumption should have a low concentration of chemicals or other substances that may present a hazard to health. In addition, to meet aesthetic needs, the water should, as far as possible, be without turbidity, colour or disagreeable taste or odour. The preparation of the Guidelines, which started in December 1978, took over three years and involved the active participation of nearly thirty Member States, scores of scientists and meetings of ten task groups. In addition, many WHO collaborating centres were involved. The process of preparation of the WHO health criteria documents involved the solicitation of national contributions, consolidation of these contributions into draft documents, circulation of the draft documents for comment to
WPR/RC35/12 page 3
national institutions designated by governments as focal points for collaboration with WHO, and review and assessment of the draft documents by a group of internationally recognized experts. WHO also collaborated with international and other organizations contributing to the programme. The health criteria documents provided the basis for recommendations on levels and limits for the various water quality parameters. In the development of the Guidelines, a major departure was made from the previous practice of prescribing international standards for drinking-water quality. The main reason for this was to recognize the desirability of adopting a risk;_benefit approach (qualitat ·ve or quantitative) to national standards and regulations. Standards and regulations ac 1ieve nothing unless they can be implemented and enforced, but these activities themselves imply the need for facilities and expertise (which, in turn, may involve significant costs). Furthermore, water is essential to sustain life and must be available even if the supply is of a less than desirable quality. Adoption of stringent drinking-water standards could limit the availability of water supplies that meet those standards - a significant consideration in regions experiencing a water shortage. It is to be expected, therefore, that those standards that are adopted wiU be influenced by national priorities and economic factors. However, considerations of policy and convenience must never be allowed to overshadow the primary objective of drinking-water standards, which is public health protection. The Guidelines for drinking-water quality! consists of three volumes, which are briefly described hereunder. VOLUME I - Recommendations presents recommended guideline values, together with essential information required to understand the basis for the recommended guideline values as well as information on monitoring requirements and, where possible, suggestions regarding remedial measures to ensure compliance with the guideline values. It provides guidelines with respect to the microbiological, biological, chemical and physical aspects,. as well as on radioactive materials in drinking- water. Summary tables of guideline values are attached (see Annex I). VOLUME II - Health criteria sets out the health criteria for those drinking-water pollutants and other constituents which were examined with a view to recommending guideline values, and also provides selected information on the detection of some contaminants in water as well as measures for their control. It contains a review of the toxicological, epidemiological and clinical evidence which was available and utilized in deriving the recommended guideline values. VOLUME III - Drinking-water quality c()ntrol deals specifically with the problems of small communities, predominantly those in rural areas. It contains information on techniques for the assessment and control of contamination of such supplies. It covers simple methods for sampling and analysis, sanitary surveys and other means of investigating and controlling drinking-water quality in these areas.
J World Health Organization Guidelines for drinking-water quality, Vol. 1, Recommendations, Geneva, 1984. Only Volume 1 of the Guidelines had been published at the time of issue of this report.
WPR/RC35/12 page 4
3.
APPLICATION OF THE GUIDELINES
The Guidelines for drinking-water quality is intended as a basis for the development of standards which, if properly implemented, would ensure the safety of drinking-water supplies. It must be emphasized that the levels and limits for water constituents and contaminants that are recommended in the Guidelines are not standards themselves. In order to define standards, it is necessary to consider these recommendations in the context of the prevailing environmental, social, economic and cultural conditions of a specific country. The guidelines that have been developed provide a basic quality goal against which the suitability of water for drinking purposes can be judged. It is intended that they should be applied in developing standards not only for community piped-water supplies, but also for all waters used for drinking purposes, including water from community standpipes and wells and water distributed by tanker or in bottles. The Guidelines for drinking-water quality can also serve as a basis for developing standards for water supplies serving transient populations (e.g. transportation terminals, trains, boats, aircraft, pilgrimage and refugee centres, camps, rallies and fairs) as these have been implicated in a number of epidemics of waterborne diseases. The use of the water quality criteria and the selection, development and adoption of national standards are important elements in the concept of safe drinking-water quality. However, this is only one part of a total programme for realizing the provision of safe drinking water. The national standards must be incorporated into drinking-water monitoring and surveillance activities, and these must be incorporated into all phases of water supply and sanitation facilities development, including planning, programming, design, construction, operation, maintenance and repair. Furthermore, there must be recognition and conviction on the part of both government and community, including users in rural and urban areas, of the importance of safe drinking water.
4.
RECOMMENDATIONS
With a view to facilitating realization of the goals of the International Drinking-Water Supply and Sanitation Decade, and having regard to the importance of effective monitoring, surveillance and control activities in ensuring safe drinking-water supplies, Me.nber States are urged to give consideration to the following recommendations: (1)
Public agencies involved in the provision of drinking-water supplies should be charged with the responsibility of ensuring the safety of drinking water in their service areas. In this respect, responsible authorities are urged to develop national drinking-water standards from the Guidelines for drinking-water quality. Responsible public agencies should recognize the need to develop programmes for monitoring, surveillance and control of drinking-water supply. This includes sampling and laboratory analytical support programmes to ensure compliance with established standards.
(2)
WPR/RC35fl2 page 5/6
(3)
Community-level information and education programmes should be promoted to create an appreciation of not only the people's rights to a safe drinking-water supply but also their communal responsibility to use and maintain systems wisely and well, whenever they are directly involved in their operation and maintenance.
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ANNEX 1 SUMMARY TABLES OF GUIDELINE VALUES In presenting this summary of guidelines values (Tables 1-5), it is not intended that individual values should be used directly from the tables. Guideline values must be used and interpreted in conjunction with the information contained in the appropriate sections of the Guidelines for drinking-water quality. Table 1. Microbiological and biological quality Guideline value
Organism I. A. A.l
Unit
Remarks
MICROBIOLOGICAL QUALITY Piped water supplies Treated water entering the distribution system number f 100 ml number/100 ml 0 0
faecal coliforms coliform organisms
turbidity <. 1 NTU; for disinfection with chlorine, pH preferably < 8.0; free chlorine residual 0.2-0.5 mg/ litre following 30 minutes (minimum) contact
A.2
Untreated water entering the distribution system number f I 00 ml number/ 100 m1 0 0
faecal coliforms coliform organisms
in 98% of samples examined throughout the year - in the case of large supplies when sufficient samples are examined in an occasional sample, but not in consecutive samples
coliform organisms A.3
number f 100 ml
3
Water in the distribution system numberflOO ml number/100 ml 0 0
faecal coliforms coliform organisms
in 95% of samples examined throughout the year - in the case of large supplies when sufficient samples are examined in an occasional sample, but not in consecutive samples
coliform organism:;
number/100 ml
3
WPRfRC35/12 Annex 1 page 8
Table 1.
Microbiological and biological quality (continued) Guideline value
Organism B. Unpiped water supplies
Unit
Remarks
faecal coliforms coliform organisms
numberflOO ml numberjlOO ml
0 10
should not occur repeatedly. If occurrence is frequent and if sanitary protection cannot be improved, an alternative source must be found if possible
C.
Bottled drinking-water numberflOO ml numberjlOO ml 0 0
faecal colifc rms coliform organisms D.
source should be free from faecal contamination
Emergency water supplies numberjlOO ml number I 100 ml 0 0
faecal coliforms coliform org.:misms Enteroviruses
advise public to boil water in case of failure to meet guideline values
no guideline value set
II.
BIOLOGICAL QUALITY no guideline value set no guideline value set no guideline value set
protozoa (pathogenic) helminths (pathogenic) free-living organisms (algae, others)
WPRJRC35fl2 Annex 1 page 9
Table 2. Constituent arsenic asbestos fbarium beryllium cadmium chromium cyanide fluoride Unit mg/1
Inorganic constituents of health significance Guideline value Remarks
mgjl mgjl mgjl mgjl
0.05 no guideline value set no guideline value set no guideline value set 0.005 0.05 0.1 1.5
natural or deliberately added; local or climatic conditions may necessitate adaptation
hardness lead mercury nickel nitrate nitrite selenium silver sodium mgjl mg/1 mgjl (N) mgjl
no health-related guideline value set 0.05 0.001 no guideline value set 10 no guideline value set 0.01 no guideline value set no guideline value set
Table 3. Constituent aldrin and dieldrin benzene benzoll_a] .>yrene carbon tetra :hloride chlordane chlorobenzenes
Organic constituents of health significance Guideline value 0.03 Remarks
Unit J.Jg/1 ~g/1 ~-Jg/1
wa
pgjl ~g/1
pgjl
0.01 a 3a 0.3 no health-related guideline value set
tentative guideline valueb odour threshold concentration between 0.1 and 3 J.Jg/1 disinfection efficiency must not be compromised when controlling chloroform content
chloroform
J.Jg/1
WPR/RC35/12 Annex 1 page 10
Table 3. Constituent chloropheno1s
Organic constituents of health significance (continued) Unit pgjl
Guideline value no health-related guideline value set IQQC 1 lOa 0.3a 0.1 0.01 a 3 30 10 lOa 30a 10a,c no guideline value set
Remarks odour threshold concentration O.lJ..Jg/1
2,4-D DDT 1,2-dichloroethane 1,1-dichloroethened heptachlor and heptachlor epo:xide he:xachlorobenzene gamma-HCH (lindane) methoxychlor pentachlorophenol tetrach1oroethened tr ichloroethened 2,4,6-tr ichlorophenol tr ihalo me thanes
).Jg/1 J..Jg/1 pgj1 pgj1
f.).g/1 ).Jg/1 pgfl pgj1 pgjl pgjl
J.Jg/1 pgfl
tentative guideline valueb tentative guideline valueb odour threshold concentration, 0.1 ).Jg/1 see chloroform
aThese guideline values were computed from a conservative hypothetical mathematical model which cannot be experimentally verified and values should therefore be interpreted differently. Uncertainties involved may amount to two orders of magnitude (i.e., from 0.1 to 10 times the number). bwhen the available carcinogenicity data did not support a guideline value, but the compounds were judged to be of importance in drinking-water and guidance was considered essential, a tentative guideline value was set on the basis of the available health-related data. CMay be detectable by taste and odour at lower concentrations. dThese compounds were previously known tetrachloroethylene, and trichloroethylene, respectively. as 1, 1-dich1oroethylene,
WPR/RC35/12 Annex 1 Page ll
Table 4. Constituent or character is tic aluminum chloride chlorobenzenes and chlorophenols colour copper detergents
Aesthetic quality
Unit mgfl mgfl
Guideline value
Remarks
0.2 250 no guideline value set 15
these compounds may affect taste and odour
true colour units (TCU) mgfl
1.0 no guideline value set 500
there should not be any foaming or taste and odour problems
hardness hydrogen sulfide iron manganese oxygen-dissolved pH sodium solids-total dissolved sulfate taste and odour temperature turbidity
mgfl
(as CaC03) not detectable by consumers 0.3 0.1 no guideline value set 6.5-&.5 200 1000 400 inoffensive to most consumers no guideline value set 5
mgfl
mg/1
mgfl
mgfl mgfl
nephelometric turbidity units (NTU) mgfl
preferably < 1 for disinfection efficiency
zinc
5.0
WPR/RC35 /12 Annex 1 page 12
Table 5.
Radioactive constituents Guideline value 0.1 1
Constituent gross alpha activity gross beta activity
Unit Bqfl Bq/1
Remarks (a) If the levels are exceeded more detailed radionuclide analysis may be necessary. (b) Higher levels do not necessarily imply that the water is unsuitable for human consumption.