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Re: Phosphate in municipal water

> Do all municipal water supplies have phosphate or is it confined to
>  areas with nearby agricultural uses?  Appreciate any advice on this
>  matter!!!
Most, if not all, municipal water treatment plants add phosphate to the water 
in the form of Zinc Phosphate.  This is done to reduce corrosion in old iron 
pipes in the distribution system.  In the pipe, Zinc is exchanged for Iron.  
The Zinc coats the interior of the pipe, sort of "galvanizing" the pipe and 
making it more resistant to corrosion.  The Iron attaches to the Phosphate, 
and thus you get Iron Phosphate, sometimes listed as Ortho Phosphate, 
discharged from your tap.  In humans this is insignificant, and may actually 
have a little health benefit to you (by providing you with some iron for your 
blood and phosphorus to help build strong bones).  In an aquarium it's a 
different story.  You say your average phosphate in your water is around 0.6 
ppm.  That's a pretty typical average level for municipal water.  You will 
never get consensus as to how much phosphate is "too much" phosphate in an 
aquarium.  The usual level that is considered "too much" is around 1 ppm.  
However, some purists who have fought the algae wars want their phosphate 
limited to 0.2 ppm.  Your mileage may vary...