Sharon - If you mean an alkaline pH of the tap water, we have been using it 
since I starting working here.  Our tap water has a pH of 8.3.  We have 
found it does not hurt staining - in fact, hematoxylin blues more readily 
because of the alkaline pH.  We use it in the water baths, for everything 
where we use tap water and have noticed no differences in staining from 
that and deionized water.  Cheryl