I too had a problem with my plastic trays collecting food which would then
be dampened by water bottle drips and eventually "grow" maggots.  My simple
solution was to install "drip catchers" under the water bottles.  There is
a ceramic dish called the "24-hour ferret bowl" that is available from a
number of catalog and online suppliers.  It has low sides that are
vertical.  I slide this bowl under the water bottle, and take a miniature
bungee cord (from WalMart) and stretch it around the sides of the bowl
(which is why you can't have sloped sides) and anchor it to the cage.
Problem solved!
 
- Erika Matulich and the Nifty Nine
[Posted in FML issue 3161]