Works well when they let water through, but very prone to clogging and blocking water flow. I've had this happen on brand new and older filters, causing a lot of frustration that my filter pitcher isn't filtering. (Cerra Customer Service: Some source water has more particulates and contaminates to filter out which can cause the filter to clog up sooner then expected. Taking the filter out and shaking it up can improve water flow and extend lifespan of the filter.)