Cat water fountain filters: when to replace them and which to buy

Which replacement filter fits your fountain?

These two manufacturer filter packs match the standard PIXI and Cat Mate three-level fountain covered in our cat water fountain buying guide. Both Amazon UK listings were in stock, sold and dispatched by Amazon when checked. Check the selected pack and seller again before ordering.

Catit identifies its PIXI pack sizes and references. Closer Pets lists the compatible models for cartridge 386, which is suitable for hard and soft water. Use those model lists rather than a retailer's broad “universal” wording.

For a third-party cartridge, look for an explicit match to your fountain model, its dimensions, construction and fitting instructions. A compatible shape alone does not establish equivalent filtration performance. The options above are the manufacturers' own cartridges; this guide does not rank alternative brands.

How often should you replace a cat fountain filter?

The PIXI manual specifies every three to four weeks, or sooner with heavy debris or restricted flow. Catit's filter product page says every 30 days. Follow the instructions supplied with your equipment and respond to its condition rather than stretching the interval to the longest number you can find.

The Cat Mate 335 manual recommends monthly replacement for one cat; multiple cats may require earlier changes if the cartridge blocks.

Write down the date you fit each filter and set a reminder to inspect it. If it needs replacing early, note why. That gives you a useful household routine instead of a drawer full of cartridges and a vague feeling that you changed one recently.

Can you wash and reuse the old filter?

A maintenance rinse is not a new service life. PIXI's manual calls for a filter rinse every three days and says not to use soap. It still specifies replacement. Keep cleaning products and descaling treatments out of cartridges unless their own instructions explicitly permit them.

How to replace the filter

1. Check the new cartridge first. Compare its model reference with the packaging or manual before opening a multipack.
2. Unplug with dry hands. Remove the old cartridge using the fountain's instructions, keeping electrical connectors dry.
3. Prepare the replacement as directed. Cat Mate's manual tells you to rinse its new cartridge under the tap to remove charcoal dust. Follow your particular filter's preparation instructions; there is no single soaking time for every brand.
4. Clean the surrounding parts. A fresh cartridge deserves a clean holder. Follow our fountain cleaning steps for the reservoir and pump.
5. Fit, refill and check. Seat the filter in the correct orientation, assemble the fountain and refill to its specified level. Confirm normal flow after reconnecting power.
6. Record the change. Keep one unopened compatible spare if that helps you replace on time. You do not need to establish a regional distribution centre.

Compare cost per filter, then annual cost

Cost per cartridge = pack price ÷ number of cartridges. Include delivery and check whether the displayed offer requires a subscription. Compare like-for-like filter types; a larger pack is not automatically better value.

For a rough annual budget, multiply that unit cost by the number you expect to use. Replacement every three to four weeks means around 13–18 cartridges across a year; monthly means around 12. Earlier changes increase that total. These are planning estimates, not a reason to keep an exhausted cartridge in service.

Keep the current price with the retailer rather than rely on a figure copied into an article. If you choose a subscription, set deliveries around your actual use and existing stock. A discount is less helpful when the cupboard is becoming mostly filters.

What if water flow is still weak after replacement?

Do not immediately open another cartridge. Check the water level, filter seating and reassembly, then inspect the pump as the manual directs. For pump cleaning and model-specific limescale instructions, use the cleaning and descaling guide.

Keep an ordinary water bowl available while investigating. If the problem persists after the manufacturer's checks, contact support with the fountain model and what you have tried. A new filter cannot repair a damaged pump.