If you open your handheld showerhead and see that your filter is much darker than it was when you originally placed it, it is time to replace it. Generally, every four months is a good time to start thinking about changing your filter. If you are the only person who uses the restroom, you should change the filter every 4 to 6 months. Households of two or fewer individuals should inspect the water shower filter more frequently - every 16 weeks. Finally, if there are more than two individuals in the house, the gallons of used water will be significantly higher. As a result, inspecting your filter every eight weeks is a smart idea.