Product review (5 stars): Do your research before judging
There are a few negative reviews where they tested the water between the tap and the filtered water with a TDS/PPM meter. I went down the same rabbit hole and came to the same result. We have really good tab water to start with measuring only 26 PPM. The filtered water from the IC-EZ-4 measured 34 PPM. I measured every water source around the house and found all the various filtered water sources had a higher TDS result than the tab water. The only source I could find that was lower was rain water from a bucket outside (7 PPM).

  These results led me to believe the same conclusion other have made in that water filters were a scam but then I did my research. Good filters do not filter out the beneficial minerals that naturally are in good water.  The filters concentrate on the chemicals that are added to disinfect the water and other pollutants. Through the filtering process the water is ionized curating a positive charge. It is the positive charge the TDS meter measures as an indicator of dissolved solids. In turn, the ionization from filtering results in false increase in PPM. Inversely, the higher TDS measurement indicates the filter is doing its job.

  Now that that is out of the way, the Culligan EZ-4 filter and filter head is outstanding. The head was relatively easy to install, the tubing plugged in with no leaks and the water smells and tastes, well, it has no smell or taste. A template to use rather then working around the head in tight places would have been nice. The screws were to long for my application so I dug through my junk drawer to find shorter screws. However, the end result is clean and perfectly functional filter system.