Like a fool, I purchased two CrystalQuest water filters over the course of a couple years and several hundred dollars. Each time, the wrong filter cartridges had to be exchanged. But the main problem is that all the filters produced a chemical aftertaste. With my first 2-stage filter, a female representative, who is no longer with the company, admitted that customers had complained about a "chemical" aftertaste; so she sent me a carbon cartridge to remove the flavor. Even the water filtered through the additional carbon cartridge had to be filtered through a Brita pitcher - filtered CrystalQuest water had to be filtered by Brita! Thereafter, I ordered a 3-stage filter, but the chemical flavor became too strong (CrystalQuest uses mechanical and chemical filters). I asked CrystalQuest to simply replace the chemical cartridges with only carbon ones, but they refused because the filters were no longer under warranty. I contacted the Better Business Bureau, and the BBB ended up giving CrystalQuest the stamp of approval without testing the water quality of the product or checking into the "chemical aftertaste." Finally, without any resolution, I threw the filters away and remained with Brita. With Brita, I no longer have a chemical aftertaste. I've used PUR in the past, too, and PUR didn't have any chemical flavor either. CrystalQuest filters leak a strong chemical flavor. CrystalQuest does not explain what this chemical flavor could be, and denies that any customers have complained about this aftertaste even though a representative once acknowledged this complaint made by numerous patrons. The chemical leakage could be toxic for all I know, but no one is providing safety data.; CrystalQuest doesn't even want to investigate the chemical aftertaste in order to improve their design and safety. Since people do not have a home lab to conduct water analysis, it is difficult to regularly test (in real time) the safety and chemical leakage of a water filter. It's not like a recalled electrical gadget that caught on fire. Water filters aren't monitored well, and complaints about chemical aftertaste are ignored. Who knows what I have been drinking all these years! I'm sticking with carbon filters because they're one of the safest.