Just to clarify, did they tell you the water in your tank had to much ammonia or the water coming out of your tap had to much ammonia?
If it is your tank, then use the advice from above. if the water in your tank has to much ammonia you just need to do more frequent larger water changes,it has nothing to do with your tap water. and you should not use softened water(filtered/bottled water)
If its your water I hope to dear god you are not drinking it :S I have seen some people, expecially if they are on well water, that their water has high amounts of ammonia in it(due to farm run off, doesnt that sound lovely?)and they need to use bottled water, adding dissolved minerals into the water to make it a bit harder.
Did you bring your tap water in to get tested or your tank water?