I sympathise with the cistern problem as I also have had to use cisternas on my finca in the past. However I would like some things made clear from a previous post. Are you,Pip, solely a concerned finca owner or do you have an interest in Purewaterspain(PWS).
You state that osmosis units produce "dead water" but surely this is innacurate if,as you say, the units don't remove bacteria. And how is pure filtered water"dead"?

I seem to remember Reading an advert for the proposed filtration system(please correct me if I am wrong as it was a few years ago) that suggested osmosis units didn't do the job as they needed a carbon filter which struck me as odd because I knew for a fact osmosis units do come with a carbon filter.
For the record I am solely a concerned/interested finca owner. I have nothing against PWS and use an osmosis unit myself and have friends who have used them for several years with no problems so I am interested in the answer.

On a separate note, with Hazelnut seeming quiescent for awhile I sincerely hope I am not becoming the forum grump and hope that this post doesn't sound to pompous.
Bruixot