Giant New Water Bowl

Jake and Elwood get fresh food and fresh water every morning.  Nice, cold water in their very own bowls.  They do not have to search for this water or work for this water.  It has been in the exact same place every day for the past 5 years.  Why, then, do our cats now find it necessary to drink from Staley's bath tub...every time she has a bath?  It's a mystery to me.