Do cat fountains really need a filter?

A fountain without a filter is a pump moving the same water in a loop. The filter is what makes the loop worth it.

What a filter does

• Carbon: removes odors and off-tastes.
• Ion-exchange resin: softens tap water and holds heavy metals.
• Cotton or non-woven fabric: catches hair, crumbs and dust.
• Pump sponge: keeps debris out of the motor.

Running without one

Fur and food collect in the pump, the flow drops and the motor works harder. The water keeps moving, but it isn't any cleaner than a bowl — and moving, fresh-tasting water is the reason pets drink more from a fountain.

If you use bottled or filtered water

Softer, cleaner water makes the carbon and resin last longer, but the hair-catching layers and the pump sponge are still needed. Keep to a regular change and stretch it only if the water stays clear.