Introduction
Laboratory testing for a winery usually is thought of as dealing only with wine, but there is another important liquid that should be tested regularly – your drinking water. If your winery is not on “town water”, that is if you use tank water for drinking water then you may be risking the health of your staff and customers if you are not maintaining your tanks or getting the water quality checked regularly.
Safe drinking water in wineries: some case studies
Vintessential Labs have been offering Drinking Water Testing for a number of years and during that time have seen some interesting experiences.
A recent example in Victoria occurred at a winery that has a very well known restaurant business. One unwell staff member had been diagnosed with Giardia so we were asked to test their tank water, the same water that was given to customers in the restaurant. The testing showed extremely high levels of thermotolerant coliforms and was highly likely to be the source of the infection of the staff member. The tank water was certainly not fit for consumption. Who knows how many restaurant patrons went home feeling unwell?
On another occasion a relatively young and fit rural customer complained of having had stomach pains for a couple of years. He had been to the doctor and had not been able to figure out what was the cause of the illness. He was finally advised to get his home water tested. He brought a sample to us and upon discussing his situation and what testing he required we determined that his household tank water came directly from his farm dam where his cattle had open access. He didn’t need our testing service – he simply needed to stop drinking the highly infected dam water!
Water test guidelines
The Australian Drinking Water Guidelines (ADWG) are the recommended source for tests for drinking water in Australia. They have been developed by the National Health and Medical Research Council (NHMRC) as the reference for the safe supply of drinking water.
To quote from the NHMRC;
“The ADWG is designed to provide an authoritative reference to the Australian community and the water supply industry on what defines safe, good quality water, how it can be achieved and how it can be assured. The guidelines have been developed after consideration of the best available scientific evidence and provide a framework for good management of drinking water supplies to ensure safety at point of use.”
What tests should be done?
The following is again from the AWDG:
“Routine monitoring for specific pathogens is not recommended. Monitoring for microbial indicator organisms, which is relatively simple and inexpensive, is used for this purpose. E.coli (or thermotolerant coliforms) is the recommended indicator for faecal contamination while total coliforms and heterotrophic plate counts can be used for operational monitoring. Monitoring drinking water for E. coli (or thermotolerant coliforms) as a verification measure is a useful tool within a risk management approach to water quality.”
Instead of testing for particular organisms in water we perfrom main 2 tests that the AWDG guidelines recommend. As the ADWG state it can be a very expensive and time consuming exercise to test for every possible organism so indicator organisms are used to give a good idea of whether the water is fit for drinking or not.
A side note: one of the reasons why wine has been such a popular drink through the ages is because no harmful micro-organisms can live in the high alcohol environment as compared to water. So until recently if you drank only wine you could not catch cholera, typhus etc as was relatively common. As recently as 1854 there was an instance of over 500 deaths from cholera in London in less than 10 days, shown to be caused from one water pump (ref Ideas…).
So the tests that are recommended to check water for microbial impurities are:
- Thermotolerant Coliforms (or alternatively, Escherichia coli, commonly known as E.coli)
- Heterotrophic Bacterial Count
Sampling
The taking of samples for bacterial testing in water needs to be done quite carefully. The samples need to be taken from a point where the water is commonly taken from, e.g. a kitchen or cellar door tap. The sample point needs to be flushed and the sample taken in a sterile container (these are available from Vintessential free of charge). The sample also needs to be tested within 24 hours of the sample being taken, so logistical matters need to be well organised as well.
Results and what they mean
As in wine microbiology the units of measurement are colony forming units per millilitre of sample (cfu/mL).
The accepted limit for Thermotolerant Coliforms is 0 cfu/mL that is no coliforms should be found in drinking water. If any coliforms are found then the water is deemed not suitable for consumption. Although only some forms of E. coli are pathogenic the presence of any strain is a relevant indicator of contamination.
Heterotrophic Bacterial Counts (also known as Heterotrophic Plate Count) can be useful for checking the performance of a water collection or treatment system. Heterotrophs are organisms that require an outside source of carbon that is required for their growth, this grouping also includes bacteria. This test is a measure of all bacteria that grow within the condition of the test used and is widely used internationally to check water quality.
Sources of coliforms
The presence of E. coli organism’s shows that faecal contamination has occurred recently as E. coli is not known to multiple in water. The source of coliforms in water can be from soli contact, faecal contamination or biofilms on fixtures or pipes. Because of the widespread distribution of coliforms in soil it cannot be assumed that a coliform presence is necessarily from faecal sources. It is not possible to determine if the source of contamination is specifically from human animal or bird origin, however the presence of any E. coli should be considered a risk to health.
Conclusion
As well as testing wine in a winery setting drinking water should also be considered for health and safety reasons for both staff and customers. The testing required to check the quality of drinking water is available but requires specialised laboratories and careful sample management. If you are not using potable water from a reticulated town water supply then you should seriously consider getting your rain or ground water tested to ensure it can be fit for purpose.
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