How about independant water treatment/sanitation?

if I have any bright ideas about the whole sentence, I'll update - but I think the idea is that these are sanitation systems that work for a small group of buildings, rather than citywide. "Stand-alone" would be the normal English word for this.

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Note added at 8 mins (2006-08-07 15:15:29 GMT)
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http://www.sabiotech.co.za/news.html

This link contains references to 'stand-alone sanitation systems'.

Another idea - 'decentralised'.

This is really what they're talking about, isn't it?

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Note added at 19 mins (2006-08-07 15:26:30 GMT)
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Of course, it may not be 'private' as in one per house, but it could be 'individual' in the sense of a small group of houses or area having their own; alternatively, you might prefer to use 'independent', as Paula suggestd in part of her answer.

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Note added at 19 mins (2006-08-07 15:27:02 GMT)
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Or of course, 'self-contained'

Google gives 51,000 references!

including:
"This ordinance is enacted to provide minimum standards for the regulation of individual sewage treatment systems (ISTS) including: their proper location, ...
www.co.hennepin.mn.us/vgn/portal/internet/hcdetailmaster/0,...

"This publication contains information on the design, installation and maintenance of individual sewage treatment systems. An individual sewage system both ...
www.ext.nodak.edu/extpubs/ageng/structu/ae892-1.htm"


I hope that this quotation that I found on http://water.usgs.gov/wrri/98grants/PADisseminating.htm doesn't apply! "Millions of rural homeowners rely on individual rather than community water systems for their drinking water. Surveys of individual water supplies in Pennsylvania and throughout the United States have repeatedly shown that these wells, springs, ponds, and cisterns often deliver unsafe or aesthetically unappealing water (Francis et al., 1982; Sharpe et al., 1985; 1993; Swistock et al., 1993). The high incidence of water quality problems in individual water systems is likely because they are not subject to the same construction and water quality standards that regulate community water systems. As a result, many individual water wells have never been tested and their owners are generally uninformed about necessary water tests or locations of water testing laboratories (Francis et al., 1982). These uninformed water system owners may eventually fall prey to scare tactics and gimmicks used by unethical vendors of water treatment equipment, water testing laboratories, or well drillers. 2

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Note added at 29 mins (2006-08-07 15:36:41 GMT)
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Also:
"of development and production of individual sewage treatment plants. ... over the country of Sudan - one of the biggest and mine affected country in Africa ...
europeandcis.undp.org/files/uploads/ACU/5callresults.pdf "