Run a finger round the inside — if it feels slippery, there is biofilm, and no amount of filter changing removes it. That surface has to be scrubbed.
Filters handle taste. Biofilm is a surface problem.
The finger test
Slippery means a film has established itself. It grows fastest in scratched plastic, which is why ceramic and stainless bowls stay hygienic longer.
The routine
Weekly: rinse the foam pre-filter, wipe the bowl. Monthly: dismantle fully, scrub every surface including the pump housing, rinse, dry.
What people miss
The underside of the spout and the inside of the pump. Both are out of sight, and both are where the film is thickest.
Materials matter here
A plastic fountain two years old is scratched, and scratches hold what a sponge cannot reach. That is the argument for ceramic or stainless, and it is a hygiene argument rather than an aesthetic one.
This does not replace your device’s manual. Blade temperatures, locking mechanisms and cleaning procedures differ from model to model, and the manufacturer’s instructions take precedence over anything written here. Unplug a device before dismantling it, check a hot blade or an air nozzle against your own hand before it goes anywhere near an animal, and keep a mechanism that closes or rotates under supervision until you know how it behaves.
Last reviewed 2026-08-17