My Mom has a brita water filter she hasn't changed in a long time & she has a rash.Could it be from the water?

Question:

If a Brita filter isn't changed when they say (usually every 3 months), bacteria can grow in the cartridge, and the water can be unsafe to drink.

Answers:

well i just noticed that you have to leave the filter run for 5 min every time you use it so there must be a reason for that. so i could be the filter

Not likely. Tap water is officially drinkable.