The presence of safe and reliable source of water is an essential prerequisite for a healthy environment. Clean water is a resource that has often been taken for granted. Pure water is necessary for growing food, manufacturing goods, disposing of wastes, and for consumption. The objective of water treatment is to produce an adequate and continuous supply of pure and palatable water that must be -

Clean - no fine mineral or organic matter in suspension,

Colourless and odourless,

Palatable - no unpleasant taste,

Safe - no harmful organisms nor undesirable dissolved content,

Reasonably soft - no excessive amounts of soap-consuming mineral salts.

National and EU bodies with the purpose of protecting the health of the population, have prepared air water and food quality standards and guidelines. The main objective of this chapter is to compile a picture of the present state of drinking water (water intended for human consumption) in the South Eastern Health Board.

It is the duty of each of the seven Sanitary Authorities, which include County Councils and Urban District Councils, in the SEHB to take the necessary measures to ensure that, water intended for human consumption meets the quality standards of the EU Regulations. This refers both to drinking water and to supplies intended for use by food premises. Although the Sanitary Authority has the primary responsibility for the management of water resources, the Health Board, as part of its preventive health and infection control duties has a direct interest in the continuing purity of drinking water. The SEHB through its public health role has a major part in identifying threats to health, in responding to them and it becomes involved in dealing with health problems once they have occurred.

Over the years the pollution load of most receiving waters has increased. In addition to pollution from point sources, pollution from non-point (diffuse) sources, for example leaching and run off from agricultural areas, has become increasingly important.

2. Sources of Water in SEHB

There are three categories of source water for drinking water: groundwater, surface springs and surface water. In Ireland approximately 75% of the main public supplies are abstracted from surface water and 25% from ground sources. In the SEHB, four fifths (78%) of the public water supplies, are abstracted from surface sources and a fifth (22%) from ground water and surface springs (Figure 7.1). Waterford and Wexford County Councils source the highest percentage of their public water supply from ground water sources which accounts for nearly a third of their supply. The other Sanitary Authorities abstract approximately 10% of their supply from groundwater sources.

Table 7.1 Source of Drinking Water for Public water supplies in the SEHB

Area	Surface water		S/Spring water		Ground water
	Population	%	Population	%	Population	%
Carlow Co.Council	30,300	90%	0	0%	3,400	10%
Kilkenny Co.Council	36,750	80%	4,050	9%	5,300	11%
Clonmel Corporation	15,125	100%	0	0%	0	0%
Tipperary SR.	43,691	75%	8,035	14%	6,662	11%
Waterford Co. Borough	42,450	100%	0	0%	0	0%
Waterford Co.Council	22,381	54%	6,616	16%	12,090	30%
Wexford Co.Council	55,442	71%	0	0%	22,756	29%
SEHB	258,969	79%	18,701	6%	50,208	15%

Source: EPA report: The quality of drinking water in Ireland, 1996²

Public and private supplies
Approximately four fifths of the SEHB population are served by water from public supplies (Figure 7.2). A percentage of group supplies receive water from the local Sanitary Authority but are not under the control of the Sanitary Authority. This is the case in Carlow, Kilkenny, Wexford and Tipperary SR while in Waterford County Councils the majority of supplies are under control of the Sanitary Authority.

Table 7.2 Percentage of population of each Sanitary Authority supplies by public water supply

Sanitary Authority	Total Population 1996 Census	Population served by Public water Supply	Percentage
Carlow Co.	41,616	33,700	81%
Kilkenny Co.	75,336	46,100	61%
Tipp. SR and Clonmel Corp.	75,514	66,751	89%
Waterford Co. and Waterford Co. Bor.	94,680	91,087	96%
Wexford Co.	104,371	78,198	75%
SEHB	391,517	315,836	80%

Source: EPA report: The quality of drinking water in Ireland, 1996 & Tipperary SR County Council.

Monitoring and the extent of sampling is a function of the size of a population served by a given supply - the greater the number of consumers the more frequent and extensive must be the analysis. For supplies serving 1,000 persons and upwards there are a stated number of samples required to be taken in the year. However for supplies to consumers numbering less than 1,000 the degree of sampling and analysis is at the discretion of the Sanitary Authorities. The population of each Sanitary Authority on water supplies greater than 5,000, water supplies serving 1,000 - 5,000, and water supplies serving less than 1,000 persons is shown in Table 7.3.

In the SEHB 25% of the population is supplied with drinking water from supplies which serve less than 1,000 persons, of which less than one fifth are under the control of the local Sanitary Authority. This water commonly only receives rudimentary treatment and many small private water supplies have been shown to fall below microbiological standards so presenting a risk of faecal-oral disease transmission. However, these supplies are unlikely to produce a large scale risk, given the small number of consumers supplied from each source.

Drinking water supplied by group water schemes, or supplies to individuals families or to small groups of consumers are less likely to have disinfection (chlorination) equipment or if available may not be maintained or in use. These supplies are at risk of being contaminated from such sources as improperly sited septic tanks and/or animal slurry pits. This situation should improve as grants are now been provided to improve group schemes.

Table 7.3 Population of each Sanitary Authority served by size of water supply

Sanitary Authority	Public Water Supply			Private	Total Population
	Population > 5,000	Population 1,000-5,000	Population <1,000	Population <1,000
Carlow Co.	20,000	11,600	2,100	7,916	41,616
	(48%)	(28%)	(5%)	(19%)
Clonmel Corp.	15,215	-	-	-	15,215
	(100%)	-	-	-
Kilkenny Co.	24,000	21,900	200	29,236	75,336
	(32%)	(29%)	(0.27%)	(39%)
Tipp. SR	35,059	20,358	2,971	1,911	60,299
	(58%)	(34%)	(5%)	(3%)
Waterford Co. Bor.	42,540				42,540
	(100%)
Waterford Co.	20,000	12,096	8,991	11,053	52,140
	(38%)	(23%)	(17%)	(21%)
Wexford Co.	68,000	5,800	4,398	26,173	104,371
	(65%)	(6%)	(4%)	(25%)
SEHB Total	224,814	71,754	18,600	76,286	391,517

* percentages rounded to nearest whole number, therefore total may not be 100%

 

3. Contamination of water supply

The essential role of water in supporting human life means that, if contaminated, it has the potential for transmitting a wide variety of disease and illnesses.

It depends both on the original quality and also how water is protected at source, in transit, in storage, and in distribution as to whether or not water will reach the consumer in pure condition. Heightened public concerns over environmental pollution has increasingly focused on drinking water quality. The main source of potential contamination are industrial, agricultural and sewage.

The main pollution threats to water are -

A wide range of inorganic and organic contaminants from point source in urban, industrial, mining and landfill areas,
Leaching of nitrates,
Leaching of pesticides,
Acidification,
Microbiological Contamination.

Contamination of drinking water with microbiological agents can be a source of a variety of communicable diseases. With few exceptions, the major water borne diseases are transmitted by contamination of water supplies with infected human faeces or urine, so for practicable purposes a safe water supply is one protected from contact with human or other excreta and treated to destroy any pathogenic organisms inadvertently introduced. Infectious disease caused by contaminated drinking water is rare in the South Eastern Health Board.

4.1  Total & Faecal Coliforms
It is self-evident that water intended for drinking water must not contain agents of waterborne disease. However many pathogens, including bacteria, viruses and parasites, are difficult or even impossible to detect. Microbial indicators of water quality i.e. bacteria indicating either the potential for faecal pollution or that such pollution has occurred, are used, since their presence shows that pathogens could also be present. The most numerous of the faecal indicator bacteria is the coliform group, and the most suitable member of this group is the Escherichia coli (E.Coli), since it alone is derived exclusively from the faeces of humans and warm blooded animals. In practice E. coli should not be detectable in any 100 ml sample of any water intended for drinking.

Table 7.4 shows the number of exceedances for total and faecal coliforms in each Sanitary authority in 1996. Many of supplies showing coliform exceedances are from sources where chlorination has been installed. Stricter control of all existing chlorination facilities would bring about a substantial improvement in drinking water. It is important for Sanitary Authorities to maintain sufficient levels of residual chlorine at the consumers tap and also avoid elevated chlorine levels with resulting taste and odour problems.

Examples of micro-organisms known to have caused water borne infection include -

• Campylobacter species,
• Escherichia coli (certain serotypes),
• Salmonella species (including S. typhi),
• Shigella species,
• Streptobacillus moniliformis,
• Vibrio species,
• Crytosporidium species,
• Hepatitis A.

Table 7.4  Analysis of results of monitoring of Total / Faecal Coliforms Units No / 100mls

Source: EPA report: The quality of drinking water in Ireland, 1996

The South Eastern Health Board and Kilkenny County Council have developed a protocol for responding to microbiological incidents affecting water intended for human consumption. The protocol outlines clearly the steps to be taken when an infringement occurs. A timely response to infringements is essential and further investigation is instigated when residual chlorine levels are low or on when 'presumptive' coliforms are detected in any sample. If these investigations show evidence of actual or potential microbiological contamination, then effective remedial action is instituted immediately to ensure that satisfactory microbiological conditions are restored.

There are two types of chemical effects - (1) acute effects where the consequences of consumption of the contaminated water are immediately apparent, and (2) chronic effects where continued ingestion of the contaminated water products produces a long-term hazard.

Nitrates in drinking water can be dangerous for bottle fed babies up to the age of about six months. Below this age babies do not have the normal bacterial flora in their intestine, and they are unable to deal with the nitrites produced by the reduction of nitrate in the stomach. Elevated levels of nitrates can cause methaemoglinaemia or 'blue baby syndrome', a rare blood condition.

To prevent unnecessary exposure, regulatory standards and advisory levels have been established in the EU drinking water guidelines. Monitoring data of nitrates in groundwater is supplied by each sanitary authority. Alternate sources of supply may be necessary when drinking water sources contain nitrate at levels higher than the maximum allowable concentration (MAC).

In the SEHB in 1996, analysis of the results of monitoring of nitrates in 166 of the public water supplies in the seven sanitary authorities in the SEHB, showed that less than 1% (4 out of 486 tests) showed exceedances, (Table 7.6).

5.2  Fluoride
Fluoride occurs naturally in some waters and its presence in drinking water has been shown to be inhibitory to tooth decay, particularly when young children are exposed. Under the Health (Fluoridation of water supplies) Act 1960, fluoride is added to public water supplies to reduce dental cavities. The practical and scientific evidence leaves no room for doubt on the benefits to dental health arising from fluoridation to a concentration of 1 mg/l.

While the EPA report highlights the number of exceedances based on Irish MAC value of 1 mg/l, this level is stricter than the EU Directive, which gives a MAC of 1.5 mg/l. At levels of fluoride above 1.5 mg/l there is a possibility of yellow staining of teeth and at much higher levels there is a danger of bone damage through fluorosis.

From the dental benefit of fluoridation, the health Board is concerned that Sanitary Authorities maintain adequate levels in the PWS (0.8 - 1 mg/l). There are far more incidences of inadequate fluouridation of water supplies than of exceedances. The number of exceedances of fluoride by Sanitary Authority is shown in table 7.6.

Fluoride mouth washing is helpful in providing fluoride to the children who live in areas with non fluoridated water.

In 1996, 0f 150 samples determined for lead only one was in excess of the MAC.

It is proposed in the revised drinking water directive by the EU commission to reduce from 50 mg/l to 10 mg/l the maximum permitted concentration of lead in drinking water.

5.4  Aluminium
Aluminium occurs naturally in some raw water sources and it is commonly used as a coagulant in water treatment processes. In normal circumstances the aluminium is converted to an insoluble form and is thus removed from the water. It is important that residual levels remain well below the maximum admissible concentration of 0.2 mg/l.

It has been suggested that there might be an association between aluminium in water supplies and dementia; however there is no firm evidence to support this. A specialised health hazard arising from the presence of aluminium in the water is that patients on kidney dialysis machines can be fatally affected if the supply to the machine contains soluble aluminium.

In 1996, in the SEHB, 104 samples were checked for aluminium in 34 supplies. Of these 21 (20%) exceeded the MAC (Figure 7.6). Most of these exceedances were in the concentration band just above the MAC and thus not greatly over the limit.

Seven of the exceedances were in the Borris supply in Carlow, which is largely due to high background levels of aluminium in the raw water. Ten of the exceedances were in the three PWSs that use coagulation in the treatment process in South Tipperary.

Under the Environmental Protection Agency (EPA) Act 1992, the EPA is responsible for preparing a report each year, on drinking water quality in Ireland for the Minister for Environment. The data in the report are based on data provided by the Sanitary Authorities. The latest report from the EPA is for the year 1996. Exceedances by parameter in each Sanitary Authority are shown in table 7.6.

Table 7.6  Analysis of exceedances by Parameter in Public Water Supplies in Local authorities in SEHB - 1996

	Carlow Co. Council	Clonmel Corp	Kilkenny Co. Council	Tipp. SR Co. Council	Waterford Corp.	Waterford Co. Council	Wexford Co. Council
Number of Supplies	9	2	15	24	1	106	57
Number of Samples	173	54	569	320	109	267	512
Aluminium	7	-	1	10	-	2	1
Ammonium	-	-	-	-	-	-	1
Coliforms	9	3	69	41	2	31	71
Colour	4	6	12	42	-	3	2
Fluoride	3	10	23	16	-	4	16
Iron	-	2	6	17	-	7	2
Manganese	-	-	3	13	-	1	3
Nitrates	1	-	2	-	-	1	-
Nitrites	-	-	-	-	-	-	-
Odour	18	-	3	-	3	1	-
PH	2	-	2	17	-	28	2
Taste	-	-	-	-	-	-	-
Turbidity	-	-	-	14	-	3	1

Source: EPA report: The Quality of Drinking Water in Ireland - 1996

Approximately 600 pesticides (as broadly defined to include herbicides as well as fungicides and insecticides) are applied in agriculture, silviculture and horticulture. On their passage through the sub-surface environment, these 600 active ingredients are transformed into an (unknown) number of degradable products (residues). The effects of active ingredients and their residues on non-target terrestial organisms (side effects), their fate in the soil and their undesired effects in groundwater are far from known with certainty for every substance. Only a few pesticide measurements in groundwater are available for a restricted number of constituents. Out of approximately 600 pesticides, only about 30 have been monitored. These 30 pesticides are neither the most mobile, nor representative of all pesticides.

7.  Conclusion

The maintenance of wholesome drinking water supplies requires the commitment of individuals from many different disciplines: professionals in Sanitary Authorities, public health specialists, environmental health officers, public analysts and hospital microbiologists. Good communication and liaison between all these individuals is essential to enable appropriate action to be taken whenever water quality problems occur.

It is recommended that: