Product review (5 stars): this was a good lifespan. The water here is about 12 grains ...
These filters fit my Sear Kenmore refrigerator perfectly.  We use about two and one half gallons of filtered water per day for drinking, K-Cups, cooking, ect.  This filter lasted about four months before the flow rate fell.  Within a day, the "Change Filter" message lit.  Considering the incoming water quality and the usage, this was a good lifespan.  The water here is about 12 grains hard with about 150 TDS.  The water quality is good with a nice polish.  No chlorine cocktails courtesy of the city!