> Tea rings no bells for me, and it's supposed to contain fluoride. (?)

Hi William

I think the issue about fluoride was what stopped me from getting a 
Berkefeld water system a couple of years ago (I don't think it takes it 
out).

However a google searched site explains that it possibly plays an important 
part in human nutrition. The problem is that there is a very narrow range 
between enough and too much.

http://www.dls.ym.edu.tw/ol_biology2/ultranet/Nutrition.html#fluoride

"Fluoride
The value of fluoride (in ionized form, F-) was first recognized as a 
preventive for dental caries (cavities). This makes sense because fluoride 
ions are incorporated along with calcium and phosphate ions in the 
crystalline structure of which both bones and teeth are constructed.

But it may have other functions. In order to grow properly, a rat must 
consume 0.5 parts per million (ppm) of fluoride ions in its diet.

Humans get most of their fluoride in drinking water. In regions where the 
natural amount is less than 1 ppm, many communities add enough fluoride to 
bring the concentration up to 1 ppm.

Perhaps because the range between optimum and excess is more narrow for 
fluoride than for most minerals in the diet, water fluoridation has been 
controversial. Leaving aside the philosophical and political questions 
raised by proponents and opponents of fluoridation, the safety and efficacy 
of this public health measure has been thoroughly established. "

Marilyn