30 Drinking water standards

Dipti Grover

Objectives:

Students will be able to:

• Understand the need of setting standards.
• Understand the process of setting water standards.
• Differentiate between acceptable and permissible limits.
• Able to understand how standards vary from country to country

Introduction

Water covers 70% of our planet, and it is easy to think that it will always be plentiful. However, freshwater (for drinking, bathing, irrigating our farms fields) is incredibly rare. Only 3% of the world’s water is fresh water, and two-thirds of that is tucked away in frozen glaciers or otherwise unavailable for our use.

According to the United Nations, water use has grown at more than twice the rate of population increase in the last century. By 2025, an estimated 1.8 billion people will live in areas plagued by water scarcity, with two-thirds of the world’s population living in water-stressed regions as a result of use, growth, and climate change. According to WHO/UNICEF Joint Monitoring Programme (JMP) Report of 2017 about 844 million people in the world – one in ten – do not have access to clean water. First global assessment of “safely managed” drinking water and sanitation services concluded that too many people still lack access, particularly in rural areas. Some 3 in 10 people worldwide, or 2.1 billion people, lack access to safe, drinking water.

One of the greatest environmental threats to health is lack of access to safe water and sanitation. Poor sanitation and contaminated water are also linked to transmission of diseases such as cholera, dysentery, hepatitis A, and typhoid (World Health Organization, 2017). As a result, every year, 361 000 children under 5 years of age die due to diarrhoea. The risk of acquiring a waterborne infection increases with the level of contamination by pathogenic microorganisms. However, the relationship is not necessarily a simple one and depends very much on factors such as infectious dose and host susceptibility. People at greatest risk of waterborne disease are infants and young children, and those who are living in unhygienic conditions. Some pathogenic microorganisms, such as Salmonella typhi, Vibrio cholerae, Giardia lamblia and hepatitis A virus, are frequently transmitted via contaminated drinking-water. Improvements in drinking-water quality may result in substantial reductions in disease prevalence. So, to monitor the drinking water quality standards needed to be set.

Objectives of drinking water standards:

• To assess the quality of water resources
• To check the effectiveness of water treatment and supply by the concerned authorities.

Drinking water quality

Water is essential to sustain life, and a sufficient, safe and accessibility must be there for all. Improvement in accessing safe drinking-water can outcome in health benefits. Effort should be made to safe drinking-water quality. Safe drinking-water, as defined by the Guidelines, does not represent any significant risk to health over a lifetime of consumption. BIS has set specifications in IS–10500 and subsequently the revised edition of IS 10500: 2012 in Uniform Drinking Water Quality Monitoring protocol. This standard has two limits i.e. acceptable limits and permissible limit in absence of alternate source. If any parameter exceeds the limit, that water is considered unfit for human consumption.

Water quality standards

The standard prescribes the requirements, test methods and sampling procedure for ascertaining the suitability of water for drinking purpose, also describes the quality parameters set for drinking water. Water quality standards can be numeric (e.g., the maximum pollutant concentration levels permitted in a water body) or narrative (e.g., a criteria that describes the desired conditions of a water body being “free from” certain negative conditions). International drinking water standards like WHO, EPA, and Indian Standards BIS-10500 are set by respective Government Organizations’.

Water quality standards are based on variables that characterize the quality of water. Many water quality standards set a maximum level for the concentration of a substance in water which will not be harmful. For some other water quality variables, such as dissolved oxygen, water quality criteria are set at the minimum acceptable concentration to ensure the maintenance of biological functions. Water quality standards for drinking-water treatment and supply usually depend on the potential of different methods of raw water treatment to reduce the concentration of water contaminants to the level set by drinking-water standards. Drinking water treatment can range from simple physical treatment and disinfection, to chemical treatment and disinfection, to intensive physical and chemical treatment. For example numerous studies have confirmed that a pH range of 6.5 to 8.5 is most appropriate for the maintenance of human system. Total Dissolved Solids drinking water should contain sufficient minerals to keep body healthy and should not contain excess minerals that become overloaded in the body.

Standards Setting Process

Formulation of standards to protect health usually occurs in two stages, first is

The scientific or risk assessment stage: includes Hazard identification (to determine whether an agent can cause an adverse effect in humans), Dose-response assessment (Determination of the quantitative relationship between the dose and the incidence of adverse health effects), Exposure assessment (Estimation of the level of an agent to which various individuals, or populations are exposed), Risk characterisation (Estimation of the incidence and severity of the adverse effects that are liable to occur in a population due to actual or predicted exposure). Second is

The political and administrative stage, or risk management stage: includes Determination of acceptable risk (judgment of acceptable risk in which society as a whole has a role to play), Determination of public to be protected (to consider not only healthy individuals but also vulnerable population groups),Choice of control technology (to formulate a strategy and to select appropriate control techniques) Legislation/standards ( to consider existing national legal framework and identify necessary legal strategies) and Economics( to strike a balance between costs and benefits).

History of Drinking Water Standards

Originally standard was published in 1983. A report prepared by the World Health Organization (WHO) in cooperation with the World Bank showed that in 1975, some 1230 million people were without safe water supplies. These dreadful facts were central to the United Nations decision to declare an International Drinking Water Supply and Sanitation decade, beginning in 1981. There are no universally recognized and accepted international standards for drinking water. Even where standards do exist, and are applied, the permitted concentration of individual constituents may vary by as much as ten times from one set of standards to another. Many developed countries specify standards to be applied in their own country. In Europe, this includes the European Drinking Water Directive and in the United States the United States Environmental Protection Agency (EPA) establishes standards as required by the Safe Drinking Water Act. For countries without a legislative or administrative framework for such standards, the World Health Organisation publishes guidelines on the standards that should be achieved. China adopted its own drinking water standard GB3838-2002 (Type II) enacted by Ministry of Environmental Protection in 2002. In India BIS sets the drinking water standards. In VI Five-Year Plan of India had made a special provision for availability of safe Drinking water for the masses. Therefore, the standard was prepared with the objective of assessing the quality of water resources, and to check the effectiveness of water treatment and supply by the concerned authorities. In India (Bureau of Indian Standards BIS) has set specifications in IS– 10500 and subsequently the revised edition of IS 10500: 2012 in Uniform Drinking Water Quality Monitoring protocol. The nature and form of drinking-water standards may vary among countries and regions. The standard therefore categorized various characteristics as essential or desirable. During VII Five-Year Plan, 55 mini mission districts were identified with a view to meet supply of water to all the problem villages. The VIII Five-Year Plan intended to provide safe drinking water to the rural masses. It also proposed to ensure supply of desired quality and required quantity of drinking water. The first revision was undertaken to take into account the upto date information available about the nature and effect of various contaminants as also the new techniques for identifying and determining their concentration. Based on experience gained additional requirements for alkalinity; aluminium and boron were incorporated and the permissible limits for dissolved solids, nitrate and pesticides residues modified.

In the formulation of the first revision, assistance was derived from the following publications:

a)      International Standards for Drinking Water issued by World Health Organization, 1984 Geneva.

b)      Manual of Standards of Quality for Drinking Water Supplies. Indian Council of Medical Research, 1971, New Delhi.

c)      Manual on Water Supply and Treatment (third revision), Ministry of Urban Development, 1989, New Delhi.

The tenth five year Plan document of India (2002-2007) has emphasized protection of the environment and safeguarding of health through the integrated management of water resources and liquid and solid waste. Need was felt to upgrade the requirements of the standard and align with the internationally available specifications on Drinking water. The second revision was undertaken for this purpose.

In the second revision the following were considered:

1.      European Union (EU) Directives relating to the quality of water intended for human consumption (80/778/EEC) and Council Directive 98/83/EC.

2.      USEPA standard – National primary drinking water standard. EPA 816-F-02-013 Dated July, 2002.

3.      WHO Guidelines for Drinking Water Quality. 3rd Edition Vol. 2 Health Criteria and other supporting information.

4.      Manual on Water supply and treatment, third edition – revised and updated May 1999, Ministry of Urban Development, New Delhi

The standard mentions the acceptable limit and indicates its background. It is recommended that the acceptable limit is to be implemented. Values in excess of those mentioned under Acceptable render the water not acceptable, but still may be tolerated in the absence of an alternative source but up to the limits indicated under permissible limit in the absence of alternate source. The limits have been specified based on WHO Guidelines wherever available. In cases where WHO Guidelines are not available the standards available from other countries have been examined and incorporated taking in view the Indian conditions. In the second revision, test method for virological examination has been given in specification. Routine surveillance of drinking water supplies must be carried out by the relevant authorities to understand the risk of specific pathogens and to define proper control procedures .Precautions/care should be taken to prevent contamination of drinking water from chlorine resistant parasites such as Cryptosporidium species and Giardia. In India, BIS has specified drinking water quality standards in India to provide safe drinking water to the people. It is necessary that drinking water sources should be tested regularly to know whether water is meeting the prescribed standards for drinking or not and, if not, then, the extent of contamination/ unacceptability and the follow-up required. Apart from BIS specification for drinking water, there is one more guideline for water quality, brought out by Ministry of Water Resources, Government of India in 2005.

Keeping in view requirement of preparing Uniform Drinking Water Quality Monitoring Protocol, the Ministry of Drinking Water and Sanitation (MDWS), Government of India constituted an Expert Group which prepared the Protocol. The Drinking Water Quality Monitoring protocol describes specific requirements for monitoring drinking water quality with a view to ensure provision of safe drinking water to the consumers.

Requirements

Drinking water shall comply with various requirements given in different Tables having parameters concerning (Physical, General, Pesticide residue, Toxic, Radioactive, Bacteriological, virological and biological examination).

NOTE 1: It is recommended that the Desirable limit is to be implemented. Values in excess of those mentioned under Acceptable render the water not acceptable, but still may be tolerated in the absence of an alternative source but up to the limits indicated under permissible limit in the absence of alternate source in col (5), above which the sources will have to be rejected.

NOTE 2: It is recommended that the acceptable limit is to be implemented. Values in excess of those mentioned under Acceptable render the water not acceptable, but still may be tolerated in the absence of an alternative source but up to the limits indicated under permissible limit in the absence of alternate source in col (5), above which the sources will have to be rejected.

NOTE 3: It is recommended that the acceptable limit is to be implemented. Values in excess of those mentioned under Acceptable render the water not acceptable, but still may be tolerated in the absence of an alternative source but up to the limits indicated under permissible limit in the absence of alternate source in col (5), above which the sources will have to be rejected.

Table 4 Parameters concerning radioactive substances

NOTE 4: It is recommended that the acceptable limit is to be implemented. Values in excess of those mentioned under Desirable render the water not acceptable, but still may be tolerated in the absence of an alternative source

Table 5 Pesticide residues limits and test method

Sr. No.	Pesticide	Limit (µg/l)
i)	2,4- D	30
ii)	Alachor	20
iii)	Aldrin/ Dieldrin	0.03
iv)	Alpha HCH	0.01
v)	Atrazine	2
vi)	Beta HCH	0.04
vii)	Butachlor	125
viii)	Chlorpyriphos	30
ix)	DDT (o,p  and p,p  –  Isomers of  DDT,	1
	DDE and DDD)
x)	Delta HCH	0.04
xi)	Endosulfan   (alpha,   beta,   and	0.4
xii)	Ethion	3
xiii)	Gamma – HCH (Lindane)	2
xiv)	Isoproturon	9
xv)	Malathion	190
xvi)	Methyl parathion	0.3
xvii)	Monocrotophos	1
xviii)	Phorate	2

(Source: adapted from BIS, 2012.)

a) Immediate investigative action must be taken if either coli or total coliform bacteria are detected. The minimum action in the case of total coliform bacteria is repeat sampling; if these bacteria are detected in the repeat sample, the cause must be determined by immediate further investigation.

b) Although, coli is the more precise indicator of faecal pollution, the count of thermo tolerant coliform bacteria is an acceptable alternative. If necessary, proper confirmatory tests must be carried out. Total coliform bacteria are not acceptable indicators of the sanitary quality of rural water supplies, particularly in tropical areas where many bacteria of no sanitary significance occur in almost all untreated supplies.

c) It is recognized that, in the great majority of rural water supplies in developing countries, faecal contamination is widespread. Under these conditions, the national surveillance agency should set medium-term targets for progressive improvement of water supplies, In the remaining 5% sample total coliform bacteria should not exceed ten per hundred ml.

Virological Examination

a)  Ideally all samples taken from the distribution system including consumer’s premises should be free from virus. It is theoretically possible that virus disease can be transmitted by water free from coliform organisms, but conclusive evidence, that this has occurred, is lacking.

b)  None of the generally accepted sewage treatment methods yield virus-free effluent. Although a number of investigators have found activated sludge treatment to be superior to trickling filters from this point of view, it seems possible that chemical precipitation methods will prove to be the most effective.

c) Virus can be isolated from raw water and from springs, enterovirus, reovirus, and adenovirus have been found in water, the first named being the most resistant to chlorination. If enterovirus are absent from chlorinated water, it can be assumed that the water is safe to drink. Some uncertainty still remains about the virus of infectious hepatitis, since it has not so far been isolated but in view of the morphology and resistance of enterovirus it is like1y that, if they have been inactivated hepatitis virus will have been inactivated also.

d)  An exponential relationship exists between the rate of virus inactivation and the redox potential. A redox potential of 650 mV (measured between platinum and calomel electrodes) will cause almost instantaneous inactivation of even high concentrations of virus. Such a potential can be obtained with even a low concentration of free chlorine, but only with an extremely high concentration of combined chlorine. This oxidative inactivation may be achieved with a number of other oxidants also, for example, iodine, ozone and potassium permanganate, but the effect of the oxidants will always be counteracted if reducing components, which are mainly organic, are present. As a consequence, the sensitivity of virus towards disinfectants will depend on the milieu just as much as on the particular disinfectant used.

e) Thus, in a water in which free chlorine is present, active virus will generally be absent if coliform organisms are absent. In contrast, because the difference between the resistance of coliform organisms and of virus to disinfection by oxidants increases with increasing concentration of reducing components, for example, organic matter, it cannot be assumed that the absence of available coliform organisms implies freedom from active virus under circumstances where a free chlorine residual cannot be maintained. Sedimentation and slow sand filtration in them may contribute to the removal of virus from water.

f) In practice, 2-3 mg/l of free chlorine for one hour is sufficient to inactivate virus, even in water that was originally polluted.

g)  MS2 phage is indicator of viral contamination in drinking water. MS2 phage shall be absent when tested in accordance with USEPA method 1602. If MS2 phage are detected in the drinking water, virological examination shall be done by the PCR method for virological examination

Biological Examination

1.All samples including consumer’s premises should be free from biological organisms. Biological examination is of value in determining the causes of objectionable tastes and odour in water and controlling remedial treatments, in helping to interpret the results of various chemical analyses, and in explaining the causes of clogging in distribution pipes and filters. In some instances, it may be of use in demonstrating that water from one source has been mixed with that from another.

2. The biological qualities of water are of greater importance when the supply has not undergone the conventional flocculation and filtration processes, since increased growth of methane-utilizing bacteria on biological slimes in pipes may then be expected, and the development of Bryozoal growths such as Plumatella may cause operational difficulties

3.  Some of the animalcules found in water mains may be free-living in the water, but others such as Dreissena and Asellus are more or less firmly attached to the inside of the mains. Although these animalcules are not themselves pathogenic, they may harbour pathogenic organisms or virus in their intestines, thus protecting these pathogens from destruction by chlorine.

4.  Chlorination, at the dosages normally employed in waterworks, is- ineffective against certain parasites, including amoebic cysts; they can be excluded only by effective filtration or by higher chlorine doses than can be tolerated without subsequent dechlorination. Amoebiasis can be conveyed by water completely free from enteric bacteria; microscopic examination after concentration is, therefore, the only safe method of identification.

5.Strict precautions against back- syphonage and cross-connections are required if amoebic cysts are found in a distribution system containing tested water.

6. The cercariae of schistosomiasis can be detected by similar microscopic examination, but there is, in any case, no evidence to suggest that this disease is normally spread through piped water supplies.

7.      The cyclops vector of the embryos of Dracunculus medinensis which causes dracontiasis or Guinea-worm disease can be found in open wells in a number of tropical areas. They are identifiable by microscopic examination. Such well supplies are frequently used untreated, but the parasite can be relatively easily excluded by simple physical improvements in the form of curbs, drainage, and apron surrounds and other measures which prevent physical contact with the water source.

8.  Cryptosporidium shall be absent when tested in accordance with USEPA method 1622/ USEPA method 1623/ ISO 15553:2006.

9.  Giardia shall be absent when tested in accordance with USEPA method 1623/ ISO 15553:2006.

10. The drinking water shall be free from microscopic organisms such as algae, Zooplanktons, flagellates, parasites and toxin-producing organisms

SUMMARY

Drinking water standard prescribes the requirements, test methods and sampling procedure for ascertaining the suitability of water for drinking purpose. Standards may vary region to region. In the development and implementation of standards it is required that the current or planned legislation relating to water, health and local government is taken into account and that the capacity of regulators in the country is assessed .Drinking water standards were needed to assess the water quality of the resource and to check the effectiveness of water treatment and supply by the concerned authorities. For formulating drinking water standards different countries has different authorities. In India there is BIS who has set specifications in IS–10500 and subsequently the revised edition of IS 10500: 2012 in Uniform Drinking Water Quality Monitoring protocol. This standard has two limits i.e. Acceptable limits and permissible limit in absence of alternate source. If any parameter exceeds the limit, that water is considered unfit for human consumption

References

• EPA National Primary Drinking Water Regulations (NPDWRs): Code of Federal Regulations, Title 40, Part 141.
• Bureau of Indian Standards drinking water – specification (Second Revision of IS 10500), 2012.
• Mehta, D. and Mehta, N. (2013). Interlinking of Rivers in India: Issues & Challenges. Geo-Eco-Marina 19/2013 pp:137-143.
• WHO Guidelines for Drinking Water quality (2011), 4th edition. ISBN 978 92 4 154815 1., available at :http://www.who.int
• http://cgwb.gov.in/Documents/WQ-standards.pdf