32 yr old male with uti from e coli. what could cause this? was at a water park recently. ct scan good. showed mild bladder wall thickening.

Not from water park.: It is extremely unlikely that you would receive any innoculation of bacteria from exposure in a water park that could traverse your (male) urethra to cause an infection. Without a stone, I would suggest that you were likely dehydrated. Have you had any infections before? You may need to be evaluated for subclinical prostatitis that could manifest as bladder outlet obstruction/bladder thickening.