Product review (5 stars): Get these all the time.
Found they can even last longer than six months.  Of course it depends on how often you use your fridge for water and how many people are in your family.  There are two of us and the last time I let it go for about 8 months and the water still tasted fine and the pressure was still good as well.  I put it in my cart at six months and found a pleasantly reduced price when I finally purchased it.  Would recommend.