Raindrop / Pioneer Raindrop Drinking Fountain Replacement Filters at a glance: Charcoal filter for healthy drinking water Changing the filter: We recommend changing the filter after no later than 4 weeks for a single cat and no later than every 2 - 3 weeks for several cats . Cleaning of the Drinking Fountain: Clean the Raindrop Drinking Fountain once a week using a soft sponge or by washing it in the dishwasher. Cleaning the pump: The pump should be cleaned at least every four weeks. Regular cleaning will extend its life and prevent operating noise developing which is caused by limescale.