There are many factors when choosing the water treatment system that best suits your needs and finances. Educating yourself on all the aspects, benefits and limitations can help in understanding why one system costs more than another, or one lasts far longer and produces better water than another.
Below, I have provided some web sites, some from manufacturers and some for third-party publications. One of the indicators is how much a company trusts its own products; the longer (and more comprehensive) the warranty, the more likely it will last and provide good service.
You can have a "lifetime" warranty on a small, insignificant part, but doesn't mean the unit will perform well. Look for warranties that are not specified to a valve bodies but not internal parts, which are the parts that break down.
All listed are considered ?'high efficiency' models. Twin tank systems can offer some additional advantages that single tank systems cannot.
Culligan brochure. Warranty near end of pdf.
http://www.eculligan.com/brochures/medallist.pdf
Look at the warranty and some of the missing aspects that make it complete.
Culligan's premier RO
http://culliganmidmissouri.com/pdf/AC-30_Good_Water_Machine_1994-2005_01882029_(RevC).pdf
This is a very basic RO with proprietary parts. No special feature that assures the owner that it will produce great water for long periods of time. They do work as they are designed and will provide a great improvement in water for given period of time.
Ecowater warranty
http://www.clementswater.com/mainmessages/warrantyinfo.htm
These have some special features like the remote sensor for low salt. I never cared much for cabinet models but as long as they don't need service, it shouldn't be a problem.
These are very efficient and their upper models are good. You didn't mention that they offered you an RO.
Kinetico warranty
http://www.h2odoctors.com/images/pdf_kineticoWarranty.pdf
What city model did they quote? 2025, 4040, 2040?
This is an older warranty and the one major change with the K5 is instead of seven years on all parts and membrane, it is now ten years. No other warranty on an RO membrane is for more than one year!
Also the warranty follows the original owner at new locations OR a new owner at original location. Not sure how many companies offer that.
K5 RO
http://www.wateronline.com/article.mvc/Kinetico-Launches-First-Customizable-Expandab-0001
The K5 is hands down the best RO out there regardless of cost. The only major producer that uses WOW (water on water) pressurized tank instead of an air bag. This provides twice as much volume per tank, 40 gallon per day actual production, refill time nearly three times as fast and less volume in the concentrate drain water.
It is the only membrane that cleans itself, thus the ten-year warranty. There is a metering system for pre- and post-filters as to when to change them.
Also, it is the only one that is expandable where additional filter can remove troubled water elements including arsenic, viruses, bacteria, perchlorates, etc., and has a mineral filter that can add calcium and magnesium back in you water if you desire. Super system!
Not sure if I answered your questions of concerns.
Andy Christensen, CWS-II