There have already been many threads on APUG about distilled and filtered water but I'd like to ask a specific question:

Is distilled water more effective (or actually necessary) compared to filtered water through a filtration system such as the Ametek AM1 from Nova Darkroom (http://www.novadarkroom.com/product/...r_Filters.html) for particular processes?

Many formula specify 'use distilled' but I wonder if this is based more on insurance or habit rather than anything else?

Tom.