How often should cat water fountain filters be replaced?

Every two weeks is the rule SORON prints on its packs. Here's what changes that number for your home.

The two-week rule

Activated carbon and resin both have a limited capacity. In a fountain that runs all day for one cat, they're spent in roughly two weeks — after that the filter still holds back hair, but it no longer cleans the taste and smell of the water.

When to change sooner

• Two or more cats, or a cat and a dog sharing the fountain.
• Hard tap water — white scale on the pump or bowl.
• A cat that drops food or toys into the water.
• Warm rooms, where water evaporates and is topped up more often.

Signs the filter is spent

The water looks cloudy by evening, a film forms on the bowl, the flow slows down, or your cat starts drinking from the tap again. Any one of these means the cartridge has done its job.

Don't forget the sponge

The small sponge at the pump intake is the motor's only protection from fur. SORON packs hold one sponge per filter, so swap both together and rinse the pump while you're there.