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Drinking Water Quality Index of Settlements issues

Background

Implications

Regional aspects

Assessing and measuring the current situation

Indicators

Management responses

Discussion

Future directions

Recommendations

Related issues

Background

Water is essential to sustain life and a satisfactory supply must be made available to consumers (WHO 2001). The quality of life of Tasmanians places pressure on water resources as the population expects large amounts of high quality water. Pressure on water resources affects every aspect of the water cycle: the amount of water harvested from our catchments; the quality of the water we drink; and, the health of our oceans and rivers (AFFA 2001).

A key to maintaining the quality of the water supply is to reduce the rate of consumption. It is notable that much of the domestic water supplied by Hobart Water is used for purposes other than 'drinking'. It is used primarily for watering gardens (50%), in bathrooms (19%), toilets (12%), and laundries (10%). Kitchens account for about 9% of water use (Hobart Water Information Booklet 1999).

According to the NHMRC (1996) drinking water should be clear, colourless, well aerated with no unpalatable taste, odour, suspended matter, turbidity, toxic chemical substances or harmful micro-organisms. Drinking water should be safe and aesthetically pleasing. Water safety is characterised by microbiological, physical, chemical and radiological quality (NHMRC & ARMCANZ 1996).

There are links between different drinking water quality characteristics. For example, the NHMRC Australian drinking water quality guidelines (1996) note that turbidity can have a significant effect on the microbiological quality of drinking water. High turbidity can interfere with the detection of bacteria and viruses, by absorbing them onto the particulate matter and thus shielding them, and promote bacterial growth through the nutrients, which are absorbed. High turbidity has also been shown to protect micro-organisms from the action of disinfectants.

Consumption of highly turbid waters is not necessarily a health hazard, but may constitute a health risk if the suspended particles harbour micro-organisms capable of causing disease in humans, or if particles have absorbed toxic organic or inorganic compounds. It may be more difficult to maintain adequate disinfection in a water supply if the turbidity exceeds one NTU. In addition, the higher demand for chlorine can lead to increased formation of chlorination by-products, some of which can have undesirable health effects.

Chemical contaminants also have the potential to impact on drinking water quality. According to the Department of Health and Human Services, chemical testing is required when potential pollutants are identified in catchment surveys. Water suppliers are asked to test for harmful chemicals on a risk management basis using for instance Australian/New Zealand standard AS/NZS 4360:1999 - risk management. For example, if a water supply is sourced from agricultural areas, pesticide testing should be undertaken in accordance with the procedures detailed in the Australian drinking water guidelines and in accordance with a recognised risk management process (Department of Health and Human Services 2000).

Any comparison of water quality objectives is generally made by reference to the Australian drinking water guidelines produced by the National Health and Medical Research Council (NHMRC) and the Agriculture and Resource Management Council of Australia and New Zealand (ARMCANZ). The Australian drinking water guidelines recommend specific levels for many indicators of poorly treated drinking water. Microbiological contaminants have the most acute effects on human health and microbiological tests are therefore considered the most relevant for drinking water.

Implications

Past threats to the Sydney water supply illustrate the potential for harm to the public health from contaminated water (EnHealth 2000). A poor water supply system can have negative health effects on the population and visitors of Tasmania. Poorly treated or managed drinking water systems would result in an increase in illness, most likely gastrointestinal illness, in the community and visiting population. People visiting an area are more susceptible to endemic micro-organisms as they are potentially exposed to different, or higher, levels of pathogens than their place of residence (EnHealth 2000).

Provision of drinking water is an economically significant activity. Supply of drinking water in Australia has an estimated gross value of output over $6 billion. Tasmania will face increasing economic pressure to ensure drinking water standards meet stringent drinking water guidelines. Economic pressures may come from maintaining the quality of the source water and the treatment of the water (Productivity Commission 2001).

Drinking water quality is affected strongly by the source water quality and catchment conditions. Catchments isolated from human and agricultural activity generally have a lower likelihood of the transmission of pathogens, and so the level of treatment can be reduced. Protecting drinking water catchments, by isolating or reducing surrounding land uses that have the potential to contaminate water, can result in increased water quality (NHMRC 1987). Catchment responses by a number of Councils achieved improvements in drinking water quality between 1998-99 and 1999-00 (Department of Health and Human Services 2000).

Regional aspects

Over 74% of drinking water in Tasmania is provided by the bulk water carriers of Hobart Water, Esk Water and Cradle Coast Water. Local councils supply 15% of the drinking water to the State. Not all councils are involved in supplying drinking water; however, all councils regulate the Public Health Act 1997 and guidelines. The remaining 9% of Tasmanian drinking water is supplied by private systems such as tank water, river water and dam water (Productivity Commission 2000).

Persons living in rural and remote areas are less likely to have well-protected water sources and fully treated water (EnHealth 2000). Contaminated water may contain bacterial, viral, and protozoan pathogens and helminth parasites. Those most at risk of intestinal and infectious diseases are the young, the elderly and persons with a suppressed immune system (WHO 2001). Water systems in rural areas of Tasmania must be protected and treated to ensure the water meets appropriate limits of microbial control. Rural and regional areas are an important source of water supply for bulk water carriers; for example, Derwent Water Supply provided 27,428 ML or about 65% of water sales by Hobart Water in 1999-00.

Remote areas of Tasmania were experiencing the most significant problems with microbiological quality of drinking water. The actual number of times readings exceeded the Australian drinking water guidelines is considered confidential, and will not be released by the Department of Health and Human Services (DHHS). DHHS state that there were 38 local government water supply systems operating with alerts to boil water prior to use, an increase in six from the previous year, and 48 water supply systems that did not require an alert. Some fluctuation in water quality in small water supply systems can be expected due to seasonal variations. Reporting mechanisms are improving with regard notifying communities of alerts to boil water prior to use once poor water quality is identified (Department of Health and Human Services 1999).

Protection of those water supply catchments that are relatively unaffected by human contact and largely free from the atmospheric and environmental pollutants is necessary to maintain the supply of high quality drinking water at a relatively low cost. Hobart Water is in a relatively unique situation of sourcing a significant proportion of its raw water supply from highland catchments yielding high quality water. Catchment management is essential to the protection of these values.

The Catchment Management Plan for Lake Fenton/Lady Barron Creek (Hobart Water 2000) demonstrates some of the challenges that are faced in maintaining catchment values even in a relatively well-protected catchment. The study notes that the water from Lady Barron Creek is at times diverted out of the water supply system due to turbidity levels exceeding the water quality limit of one NTU (turbidity units). High turbidities limit the penetration of chlorine, which acts as a disinfectant on micro-organisms, including those that are harmful to human health such as E. coli.

Hobart Water (2000) notes that degradation to the water quality from mountain catchments is largely related to the impact of public recreational access and to infrastructure such as unsealed roads within the catchments. Hence, catchment management planning is integral to Hobart Water's ability to continue supplying customers with quality drinking water at a relatively low cost without the need for additional treatment of water sourced from a number of its catchments.

Water supplied by major councils, 1999-00

Council

Population a

ML

ML/person b

Supplier

Central Coast

20,380

4,053

0.20

Cradle Coast Water c

Circular Head

8,108

1,540

0.19

Cradle Coast Water c

Devonport

23,814

4,491

0.19

Cradle Coast Water c

Kentish

5,331

312

0.06

Cradle Coast Water c

Latrobe

7,627

325

0.17

Cradle Coast Water c

Waratah/Wynyard

13,350

1,601

0.12

Cradle Coast Water c

George Town

6,653

843

0.13

Esk Water

Launceston

62,431

10,353

0.17

Esk Water

Meander Valley

16,773

1,229

0.07

Esk Water

West Tamar

18,873

2,374

0.13

Esk Water

Brighton

12,471

1,801

0.14

Hobart Water

Clarence

47,461

8,617

0.18

Hobart Water

Glenorchy

43,066

9,760

0.23

Hobart Water

Kingborough

26,839

3,847

0.14

Hobart Water

Hobart

46,676

11,678

0.25

Hobart Water

Remaining southern
councils d

24,976

3,129

0.13

Hobart Water e

Burnie

19,283

3,500

0.18

Self-estimate f

Other councils

55,547

9,500

0.17

Self-estimate g

Total

459,659

79,953

0.17

 

    (a) Based on ABS 1996 Census.
    (b) Based on water supplied by bulk water authorities and does not include water supplied from other sources within the council area (e.g. rain tanks) or the fact that industrial consumption is greater in some areas. As a result the ML/person rate could vary in some areas.
    (c) Includes treated and untreated water. Untreated water is supplied to some large water consumers in the manufacturing sector.
    (d) Includes Derwent Valley, Sorell and Southern Midlands.
    (e) Estimated using Hobart Water's annual consumption total for 1999-00, includes water supplied to offpeak users as this could not be excluded.
    (f) Burnie City Council's annual water consumption is between 3,000-4,000 ML (Triffett 2001).
    (g) Estimated using ABS (2000) data.

Source: DPIWE 2001


Drinking water catchments and known water intakes

Assessing and measuring the current situation

A Technical Report was commissioned as part of the National SoE Report (Maher et al. 1997), which identified indicators for drinking water quality capable of inclusion for national SoE Reporting. The Technical Report noted that simple measurements of turbidity, colour, total dissolved solids, water hardness, coliform bacteria, and a handful of chemical variables have proved to be remarkably robust in their ability to track complex underlying water quality problems. To be useful, these indicators would be capable of measuring both: the quality of natural waters harvested for water supplies; and the quality of water supplied to the consumer at the tap. The Technical Report noted that The Australian drinking water guidelines (NHMRC-ARMCANZ 1996) list some two hundred and sixty measurable indicators of water quality. The costs and logistics of sampling and analysis, the almost total absence of the vast majority of toxicants and the technical difficulties associated with many analyses mitigate against any full compliance or performance assessment process. There is no point in specifying a test that costs thousands of dollars to conduct if a problem is unlikely to exist or if the ratepayers cannot afford the expense (Maher et al. 1997).

Indicators

Exceedences of Drinking Water Quality Guidelines - at a glance

A poor water supply system can have negative health effects on the population and visitors of Tasmania. Bulk water carriers and local governments are required to provide annual reporting of drinking water quality. Hobart Water and Esk Water are providing drinking water that complies with the Australian drinking water guidelines in terms of E. coli and coliform counts. Cradle Coast Water is not currently complying with the maximum allowable coliform count for drinking water. Cradle Coast Water also found that the water at the Deep Creek sample site did not comply with the faecal coliform levels of the guidelines.

Number of Boil Water Alerts Issued by Local Government Authorities Or The Department of Health and Human Services - at a glance

Given that annual reporting of drinking water quality is now only in its third year it is likely that improved testing and reporting resulted in increased alerts to boil drinking water from year one to year two. In year three of reporting, a slight decline in the number of boil water alerts occurred.

Management responses

Water supplies require treatment to make them drinkable or suitable for domestic and industrial purposes (NHMRC 1987). Disinfection at the appropriate time can remove 100% of the organisms used to indicate poor drinking water. Chlorine and hypochlorite are the most commonly used disinfecting agents; chloramines, chlorine dioxide, ozone and ultraviolet radiation may also be used (NHMRC/ARMCANZ 1996).

According to EnHealth (2000) a key to maintaining the quality of our water supply is to reduce our rate of consumption and Tasmanian households used less water in 1996-97 than in 1993-94 (Australian Bureau of Statistics 2001). There are various methods that can be utilised in an attempt to reduce water consumption such as reduced flow shower heads, shorter showers, dual flush toilets, ensuring full loads when washing, and reusing water (Australian Bureau of Statistics 2001).

The Australian drinking water guidelines have been subject to ongoing review since 1996 to ensure that the guidelines meet current community expectation and better manage the risk associated with contamination (NHMRC & ARMCANZ 1996). A number of programs to improve drinking water have been developed and local government's are required to provide increased reporting of drinking water quality in their municipality.

The Public Health Act 1997 states that an agency, public authority or person managing or in control of water must manage the water in a manner that does not pose a threat to public health. The guidelines for water quality issued under the Public Health Act 1997 state that sampling of drinking water must occur in accordance with the Australian drinking water guidelines. All results of drinking water sampling from each of the 29 Local Government authorities and the three bulk water suppliers must be published in an annual report that is made available to the public on request from the Department of Health and Human Services (Public Health Act 1997).

There is some flexibility in the approach in Tasmania as the residents of the town of Lilydale and Launceston City Council have decided not to disinfect the Lilydale drinking water supply, the town is under a permanent boil water alert (Productivity Commission 2000).

Private properties with rainwater tanks are generally not considered in monitoring conducted by the relevant agencies. Rainwater tanks are the responsibility of individual owners to maintain and monitor; advice can be sought from the relevant local authorities. Private water suppliers that supply water on demand must be registered with local government authorities under s133 Public Health Act 1997, the results are not available as a component of the annual reporting mechanism.

The DPIWE (2001) has jointly developed the State and Commonwealth Clean Water Program funded by NHT. The Clean Water Program aims to implement cost effective solutions to water management problems in small towns. One of the most significant sources of water pollution in small towns in Tasmania is sewage effluent (DPIWE 2001).

The State Policy on Water Quality Management was developed by DPIWE and applies to all surface waters, including coastal and groundwaters. The policy does not relate to privately owned waters that are not connected to, or flow directly into, waters that are accessible to the public or waters in any tank, pipe or cistern. The purpose of the policy is to provide adequate management of Tasmania's surface and groundwaters, while allowing for sustainable development (RPDC 2001).

The Standing Committee on Environment, Communications, Information Technology and the Arts References Committee has investigated Australia's urban water management. The Committee has investigated urban water management practices and policies and the effects of urbanisation (Standing Committee on Environment 2001).

Discussion

The microbiological testing regime by agencies that supply drinking water to the Tasmanian community is adequate. Drinking water for most of Tasmania is supplied by three bulk water suppliers and generally achieves the standards set by the Australian drinking water guidelines. Drinking water supplied by the Cradle Coast Water Authority does not meet the ANZECC drinking water guidelines.

The quality of drinking water is poor in regional areas with low population densities. While the number of boil water alerts has risen the actual locations of the water supply systems providing poor drinking water has not been provided. An increase in the reporting and availability of information is required to assess the condition of Tasmania's drinking water supply.

Future directions

Tasmania Together and the RMPS

Relevant Tasmania Together goals and standards for 'Settlements' are listed in the linked file. The Tasmania Together Progress Board reported on progress toward targets for benchmarks set (Tasmania Together Progress Board 2003). Indicators, targets and baseline data are available in the latest Progress Report June 2003. Further information, including progress report updates, is available from Tasmania Together.

Involvement of the community, and the fair and orderly use of resources are also fundamental principles of the RMPS. The RMPS objectives have been developed to advance the principles of sustainable development.

Recommendations

2003

Chapter Title

Recommendation Title

Settlements

Sustainable Housing

Drinking Water Quality

Related issues

Inland Waters and Wetlands

Water Quality

Land Use and Inland Waters

Water Quantity and Water Use

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