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THE GREYWATER DEBATE
THANKS KEN,
I HAV'NT SEEN THESE STATS BEFORE. PLEASE ADVISE THE SOURCE.
THE FOLLOWING INFORMATION IS CERTAINLY AUTHENTIC.
WE WILL ATTEMPT TO FIND IF ANY MEANINGFUL IMPACT STUDIES HAVE BEEN DONE.
Dear ed,
You were asking about pollution of the Murray, so these numbers given to me may be of interest:
Major causes of pollution
Primary Producers 30%
Industry 20%
Urban Run Off 14%
Recreational Boating 6%
Dwellings within 400mtrs. Of river 10%
Casual Riverbank Users 6%
Houseboat Hire Industry 2%
Houseboats 3%
Other 9%
Primary Producers include all farms, agriculture, horticulture, viticulture etc.Urban run off includes "nutrient rich" recycled water.Recreational boating includes pleasure craft.
Casual riverbank users include swimmers & picnickers.Houseboats include all craft (other than Hire Boats) with live aboard facilities.
Ken A.
26th June 2007
Dear Ed,
It's claimed that a duck "squirts" about 5 times per hour, and that the daily greywater pollution from a houseboat amounts to about 4 duck squirts.
Could you please ask Peter Scott of the EPA to comment on this, as there is a conservative two million birds living along the murray.
Thanks Tim. 5th. Aug 07
Club Murray Editor, 23rd. Aug 2007
With reference to EPA circular 3507 quote (nasty germs in grey water-laymans summary).
The data and pathogen summary as presented in the table could easily lead to a false premise as to the practical application of dealing with sullage from boats.
To extrapolate on the basis of this very limited data alone is an invitation for flawed regulation and perhaps unnecessary financial encumbrance.
The data reprinted in the circular is probably good science as far as it goes which is not far in a seminal laboratory exercise.
It was probably not intended as the sole data upon which practical application for regulating sullage is advanced: i.e. the data is representative of a mere "step along the way" towards a bona-fide result.
On it's bare face this limited data demands a number of cogent answers to salient questions.
The problem of quantifying and making sensible conclusions in this matter is fraught with many important variables to be considered - a prerequisite for sound science.
It is not evident as to how the testing methodology was applied nor the amount of collecting and testing carried out to enable credible evaluation.
Prima facie it appears as a quantum leap to conclude from this data alone that sullage is so inimical to health that houseboats must (presumably in general) have a very expensive disinfection system installed on possibly flawed risk analysis.
Not withstanding that discharge of sullage in a crowded and still-water marina aught to be avoided on pollution grounds (which is another matter as the data refers).
Escherichia Coli, a non pathogen is normally a harmless bacteria occurring in large numbers in faeces of both human and animals. It is a natural part of the intestinal flora as is Enterococci.
Most E Coli contamination of water is of an animal faecal origin - not human (apart from direct sewage discharge).
It would be more efficacious for adequate testing to be carried out on the water which it is alleged that houseboats are contaminating. This might provide more useful and practical information.
The problem of quantifying and arriving at sensible conclusions in this matter is fraught with many important variables for mandatory consideration.
E Coli is slow to reproduce in uncontaminated water and disappears unless continual faecal matter is present. It is therefore one of the useful tests for a potable or acceptable water supply for town use and more important prior to the introduction of water treatment plants.
The test remains important also for locating the source of faecal contamination.
The presence of enteric bacteria represents a warning that disease causing organisms may also be present.
However, each type of pathogen has a specific "minimal dose" in order to cause disease and this is yet another matter to be considered in risk analysis.
In a free flowing river system, reasonable conjecture would probably hold that disease risk from sullage is acceptably low.
In practical terms this is predicated on the following:
1. The prime source of E Coli in water is animal, not human.
2. In river water (particularly with reasonable sunlight penetration) ultra violet light has a significant disinfecting effect on pathogens. Retention time is also a factor.
3. Faecal matter, being the source of E Coli and other enteric organisms would have to be present in sullage. This could be considered unlikely (not withstanding the questionably value of the stated data), particularly since the universal use of disposable nappies.
4. The dilution rate of pathogens in large volumes of water mitigates also against disease risk particularly so, when this water is not generally used for drinking without treatment.
These factors amongst others bring us back to the possibility of flawed use of the presented data and or a problem with test sampling or laboratory methodology.
It seems a rather brave assumption or questionable science to say that "washing a chicken on the kitchen sink is nearly as bad as raw sewerage", and , "twenty four hour storage of sullage is as dangerous as sewage" !
From a practical and regulatory viewpoint it may be better to isolate the particulate matter of kitchen waste from the shower water sullage.
Kitchen waste fits into the pollution problem whereas water from showering using bio-degradable soaps is arguably not a problem for discharge.
The imposition of expensive disinfection systems without further thorough investigating of the practical need might well prove to be an unnecessary financial encumbrance.
In final response, the probable source of any high concentration of E. Coli in the lower end of the Murray River is likely related to the practice of discharging dairy farm and paddock effluent into the river.
Yours sincerely
Retired Public Health and Research Officer
Name and Qualifications supplied.
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