A Crampton, A Ragusa
australia, drinking, e. coli, risk, tank, water
A Crampton, A Ragusa. The E. Coli Load In Self-Managed Rural Water In Australia. The Internet Journal of Microbiology. 2009 Volume 9 Number 1.
Access to clean drinking water is taken for granted in most developed nations where many think water quality is a third-world issue. However, for residents of rural Australia water quality is an emerging issue. Our research of drinking water quality, harvesting and management practices of rural NSW residents found that a substantial number of these consumers may be risking their health whenever they turn on their tap. More than half of the tank water sampled failed to meet the Australian Drinking Water Guidelines for safe drinking water. Levels of
On the world’s driest continent (Shiklomanov, 2000), in an area living through a prolonged drought, discussion of water availability and quantity abound. However, water quality, particularly for human consumption, as opposed to water for crops and grazing, has been largely ignored. A 2008 survey of Australian urban residents from four capitals and one regional city found only 78% of respondents had considered the quality of their drinking water (Crampton and Ragusa, 2008). Australia is particularly vulnerable to threats to both the quality and quantity of drinking water availability because most rainfall evaporates quickly, resulting in twenty percent of the population relying on ground water for drinking supplies which “is extremely difficult to clean up if it becomes polluted” (NHMRC 2004, p.8).
Despite this, Australia remains one of the only western nations without legislation to ensure the quality of its drinking water (Sinclair and Rizak, 2004). The quality of Australian drinking water is managed in accordance with the Australian Drinking Water Guidelines (ADWG) which provides approved guidelines for management and processing practices as well as acceptable levels of contaminants (NHMRC, 2004). Although the majority of these guidelines are within, or more rigorous than, those advised by the United Nations, they only relate to regulated water (i.e. water controlled by an external body, government and/or industry). Further, the periodicity of water testing to ensure the guidelines are met is dependent on the population served by the water. For example, urban water might be tested weekly for some parameters while rural and regional water might only be tested monthly or bimonthly for the same parameters (NSW Health, 2005). For rural and regional residents in charge of managing their own water supplies, there is no organised testing protocol. Hence, there is no way to ensure rural residents on non-regulated water are consuming water that meets ADWG.
Impurities are expected in all water sources due to the nature of their collection and/or storage. However, it is the nature of the impurities and their effect on waters’ organoleptic qualities, or pathogenicity, which is of concern to water providers and consumers. In Australia, as in other countries, the key concern is faecal contamination of the water supply. To monitor for this, the water is screened for the presence of indicator organisms which in themselves may not be pathogenic, but are indicative of the presence of faecal contamination (NHMCR, 2004). The enteric bacterium
While there has been a plethora of studies on ‘optional, alternative water sources’, namely tank water in urban areas (Yang
Materials and Methods
Recruitment, Survey Design and Interviews
Participants were recruited via the Holbrook Landcare listserve, university listserves and word of mouth. Potential participants were sent an email outlining the commitment involved, namely collection of water and delivery to designated collection areas and participation in a 20 minute phone interview. Consenting participants were then sent a collection pack consisting of a 4 L sterile plastic jug for each water source to be sampled, a cooler bag with an ice pack, water collection instructions and a survey. The survey contained open and closed ended questions and was designed to ascertain information about participants’ water collection devices (i.e. number and type of tanks), residence particulars (i.e. land size and ownership), activities around the collection area (i.e. stock grazing or aerial spraying) and general demographics. Initial collections occurred between April and May 2009 with follow up collections of water from contaminated tanks in September 2009. Test results were sent to participants once they completed a 15-20 minute telephone interview. Interviews consisted of a series of demographic questions, queries about their water collection habits as revealed from the collection survey (i.e. why they did or did not have an inlet screen), attitudes towards water management, agricultural impacts and general perceptions about the quality of their water. The survey and phone interview questions were approved by the School of Biomedical Sciences Ethics in Human Research Committee, protocol number 6/2009/02.
Participants conducted their own water collection and brought their samples to a central location. Collection from the central location was designed to ensure a maximum of four hours between collection and laboratory analysis. Participants were instructed to collect directly from the storage source (tank or bore head) prior to daily use. The participants were given the following collection protocol: 1. Select a tap connected to your regular source of drinking water (tank/bore). 2. Remove any external filters. 3. Clean the tap with a damp cloth 4. Allow the tap to run until it fills a standard bucket. 5. Rinse the collection flask 3 times from the same source as the water to be sampled. 6. Fill the collection flask to the top so that there is minimal air space between the water and lid. 7. Place the collection flask with the ice pack in the insulated bag provided.
Follow up sampling was done in the same manner except that the collection vessels were 2, 200 ml jars per requested sample, as these samples were only tested for levels of
Microbial load determination
Laboratory analysis focused on 3 key targets,
Quantitative survey responses and laboratory results were entered into SPSS and descriptive statistics used to generate key information about the relationship between the participants, their water collection activities, their residential environment and incidences of contamination. Correlations were performed to identify if statistically significant relationships existed amongst the variables.
Recruitment yielded 48 participants who supplied 52 water samples (47 rain harvested, 4 bore and 1 spring). Participants were all from within 150km of Wagga Wagga, NSW with 44% from the Holbrook area, 24% from the Wagga Wagga area, 22% from the Albury region and the remaining 10% from Batlow, Tumut, West Wyalong and Cootamundra. Eighty-five percent of participants did not have access to a regulated water supply. The area of land on which the participants resided varied from 0.8 acres to 25000 acres. Sixteen percent lived on less than 10 acres, 9% on 50-100 acres, 27% on 100 - 500 acres, 11% on 500-1000 acres and 38% on more than 1000 acres. Sixty-five percent of participants used their land to run a commercial enterprise, with the grazing of sheep and/or cattle with some cropping being the predominant sources of income. Only 4 participants did not have a livestock-related enterprise.
The average rainfall across the collection area for 2009 was 423mm. The average maximum temperature was 31.5 °C in January and the average minimum 3°C in June. Most participants (78%) relied on rain harvested water as their primary source of drinking water; a further 9% relied on bore water, 2% on spring water and the rest relied on a combination of rain and bore or purchased water. Most tanks were constructed from concrete (53.5%), with PVC the next most popular material (16%). Most of the roofs from which the water was harvested were Zincalume/colourbond (76%). The majority (55%) of participants had only one tank, 18% had 2 tanks, 21% had 3 tanks and 5% had 4 tanks. The extra tanks were often attached to peripheral buildings, such as shearing sheds. Tank age ranged from 1 to 99 years although most (56%), were less than 20 years old. Only 48% of harvest areas (roof and area between roof and tank) had contamination prevention devices fitted (e.g. leafless gutters, leaf diverter, filter sock) with 27% using a first flush diverter. Contamination reduction devices were fitted to 86%; devices including inlet screens, fines filters, frog flaps, deep tank draw off and in one case an inline filter. Of all the fitted devices, deep tank draw off systems (64%) and inlet screens (50%) were the most predominant. Forty percent of participants had cleaned their tank at least once, yet only 3 participants indicated that it was part of their scheduled maintenance program. Eight participants had tested their water previously, but only 5 due to concerns of quality. All others were for an educational project.
Although numerous non-identified anaerobic colonies were cultured neither
Statistical analysis of the full data set combining the laboratory results and the survey yielded a correlation between tank type and
In Australia, the USA and EU, the detection of
The risk of microbial contamination in tanks can be reduced by several well known practices. These include the installation of first flush devices, cleaning gutters, both of which are designed to reduce the build up of potential contaminants and the use of filtration to remove potential contaminants before use (NHMRC, 2004b). Indeed, NSW Health, the key health authority figure for the participants in this study, has stated, “providing systems are well maintained the risk of harmful organisms being present is low” and in the same document they are cautious in their descriptions of risk noting, “a well maintained water catchment system is probably safe and unlikely to cause illness for most users” (NSW Health, n.d.). This echoes the findings of numerous studies which have shown that while most rain water is pure once it reaches the catchment surface, such as roof top or tank, its purity is affected by a myriad of factors including the degree to which the catchment system has been maintained (Richardson
Periodicity and intensity of rainfall have been shown to impact level of microbial contaminant entering tanks, and the more time between events, the more contaminants accumulate and are washed into the tank (Abbott
Inadequate maintenance, the common status for self-managed systems (Abbott
Increasing outbreaks (Callaway
In addition to bacterial-related health risks, faecal contamination carries the increased risk of viral contamination of the water source. Although viruses cannot multiply in water, some may remain static (Leclerc
While the true risk to regular consumers of tank water is debatable due to issues of acquired immunity (Heyworth, 2006) and lack of identification of distinct pathogens rather than indicators, the widespread incidence of high levels of contamination, as well as the probability that these levels underestimate exposure, highlights the need for further investigation of the quality of water available to rural residents. As Sydney Water (2003) informed consumers,
“People with special health needs such as those with a severely weakened immune systems (including some people with HIV and AIDS, transplant recipients, dialysis patients and cancer patients) should talk with their doctor about taking special care by using only boiled, bottled or microfiltered water.”
So, too, should rural residents be advised to take the same precautions with their water, especially in relation to ‘at risk’ visitors including the very young, elderly and immune compromised. This concern was also expressed by NSW Health in their rainwater tanks pamphlet, “ the very young or very old, may wish to take extra care by using only boiled, bottled or micro-filtered water and avoiding foods and beverages that may contain rainwater” (NSW Health, n.d.).
This study has shown consumption of raw tank water by rural residents in NSW, Australia, unknowingly exposed them to a level of risk not encountered by urban residents. Further, our research has shown rural consumers are ill informed about risks and correct actions to take to ensure better safety of tank-water consumption. Rural residents are regularly bombarded with a deluge of information on land management, drought relief and factors related to surviving on the land. Our research advocates greater attention must be paid to the water residents are drinking, in addition to the water used for other interests.