Took a plastic bowl that has a flat bottom and the cat circular water fountain fits in perfectly, with an extra inch all around and on the bottom.

Wrapped this bowl in bubble/aluminum reflective insulation. About 10 times. Cut 10 large squares for the bowl to sit on plus extra space. Made sure that the bowl that had been wrapped has the bottom wrap cut out so I can flare out and press against the insulation squares on the bottom.

Put that all on its own plastic tray and fill the bowl with ice and water.

Take the cat fountain apart and clean it thoroughly. Yes there was a yuck. Remove all filter material because it does nothing other than gather bacteria. It can't be washed.

Double check that nothing on the outside will ever get to the inside where the cat drinks and that there's nothing electrical that's scary.

Drop the cat fountain in the plastic bowl and walk away.

Let's see if he likes it

The water fountain is now 40°.

Nothing yucky will grow in it. At least not quickly. I will fill it with fresh clean ice water once a day along the ice bucket is in. The ice comes from a very cold freezer and lasts the entire day, at least not doing more than a 5° rise.

The cat drinks well.