Filters work most effectively when the water is dirty and are replaced frequently. You can provide your pet with fresh water. Non-woven fabric adsorbs hairballs and particles, preventing them from entering the water tank. Activated carbon and ion exchange resin can remove contaminants. The resin can also purify the water and remove harmful metals. Typically, the filter is replaced once or twice a month. Even with an effective filtration system, it is impossible to eliminate bacteria. Washing the water dispenser once every two weeks can prevent bacteria from entering. Therefore, the water dispenser is designed to be easily disassembled and cleaned. Replace the filter (cotton pad) every 2-4 weeks. Wash the water dispenser every two weeks. I also have other pet filters for sale. Discounts are available for bulk purchases. #1818 Product List 5-17