sterile or tap water for meds?

My current hospital requires sterile water. I have worked at five other hospitals; none of which have required sterile water, so this is new for me.

I am 2 yrs out of NS, and we were taught that tap water is permitted, since the gut isn't sterile anyway. Warm (not hot!) water helps dissolve those crushed meds. However, my facility policy requires use of sterile water, so that is what I use.

I always use tap water.

When I was in homecare I had to have parents try to switch from tap water (which they were boiling as per doc request) to nursery water due to babies getting diarrhea. It worked no more diarrhea. My only guess was something that boiling was not removing from the water was causing the problem.
I believe that the correct choice would be what does your patient tolerate? If there is a policy for your hospital just make sure you follow it.

To sterilize water, you need to boil it for 20 minutes. I wonder if they were doing it for long enough?

Also, my hospital's policy is tap water unless the patient is neutrapenic. Then we're supposed to use sterile water. Most nurses use sterile water regardless, but I don't (I'm just a rebel that way, haha)