Re: Cold Water Dispenser
I have just installed two of the GE activated charcoal systems... A 1 filter and a two filter system. Also had a reverse osmosis system for years... We have very good quality city water to begin with, but I have been worried about the change to the chloramines (sp?) system (lead leaching, ammonia).
The one filter system works fine and has good water flow. Replace filter(s) every 6 months (assuming 4-5 gallons per day--per instructions).
The two filter system I got is just the same as the one filter, but with two canisters in series. Water flow is not as good (perhaps 1/2 the rate as the one filter system). Got this one for my house with two young kids. Works fine to fill glasses at the sink (my wife uses a Brea (sp?) charcoal pitcher to keep cold water in the fridge).
The osmosis system was from about ten years ago--newer systems may be better. Still had to replace filters (a pre-filter and a post charcoal filter) and had problems with the O-Rings leaking (used filter cartridges in large diameter filter holders). Also had problems with noise and excessive bypass water use. My wife eventually got worried about mold and bacteria growth in the osmosis system (you are supposed to flush with bleach every so often). Also, after several years of use, the 2-3 gallon storage tank lost its air charge and would need to be refilled (tank has air bladder inside to accumulate water as reverses osmosis systems are generally not able to produce enough water flow for a point of use filling of a glass of water).
I liked the GE system because the entire filter cartridge and case is replicable (with new O-Rings) and seems like it has less chances of leaks developing. There is an upgrade filter that, I believe, can be used in the base two filter system, if you want (slightly?) better filtering. Very easy to install (The GE activated charcoal system included a cold water feed manifold installed between shutoff valve and water line to your sink tap... Small overall size).
The Reverse Osmosis system worked OK too (water tasted fine and storage tank usually provided good flow and volume--if kept charged with air). I did not like the noise (buzzing water hammer noise as system was deciding to turn off or on to fill the storage tank), the leaks from the large O-Rings/Cartridge seals, the need to flush with bleach (in theory, no taste problem as final carbon filter should catch), issue of bacteria/mold growth, problems with by-pass water line to sink drain clogging, and just an overall larger amount of maintenance required. Also, the ROS filter/valves are usually larger, and you have to find room to put a ~three gallon metal tank under your sink. And you still have (usually two) filters to replace. The ROS system, and probably many others, required you to install a "vampire" water tap on the cold water line (some may require you to drill a small hole too).
I guess, in the end, if you have good city water (not too hard) and the charcoal units give you good taste--I would try the simple system first. Also, the GE unit supplied a manifold that is easier to install (and remove)--very nice if you don't have room for a vampire tap on your cold water pipe (you should be able to use the GE manifold to connect to a ROS unit too--if you choose to install one later).
If you have hard water, lots of dissolved organics/nitrites, salts, heavy sulfur or fluoride tastes, etc., you probably need ROS to get the water quality you want. Also, if you are using a well, you may need more (like a UV sterilizer) to make the water safer--However, you would probably need to talk with a professional about this--Most store bought water purification systems (that I have seen) state very clearly that they should only be used on water supplies of known safety and quality. You will also have to install the by-pass drain, typically, by drilling a hole in your sink waste drain pipe and install a clamp (and will probably need to clean the plastic drain tube every so often). Also, if you install a ROS system, try to place the water spout in a place where leaking water will drain directly into the sink (or a leak won't cause damage)--because you can get a clog in the by-pass water drain line and the ROS water spout is where the water will leak from (vacuum break is usually in the base of the water spout).
-Bill