Question:
I'm considering purchasing a water purificationsystem so I can drink water 'from the tap'.I think I've isolated my options down to twotechnologies: carbon filter or reverse osmosis.I'm wondering if anyone can recommend eithertechnology, or any particular product.

Answer: The following are general statements:

Carbon is used to remove organic compounds, IF the flow rate throughthe unit is slow enough to allow that to happen. It will also act afilter, by virtue of the fact that the carbon "granules" or "block"will prevent passage of 'large' particles.

Reverse osmosis, on the other hand, typically is a "system" made upof a particulate fitter, carbon filter, membrane separation, storage,another carbon filter, water-quality sensing device, and deliverysystem (faucet). So, with an RO System, you get the carbon PLUSmembrane separation. PLUS, remember when I mentioned flow rates forcarbon? In an RO System, the flow rate is *typically* less than 30 -40 gallons per day, or about 0.02 gallons per minute. That slow flowrate allows the carbon to do a much better job of removing theorganics, etc from the water even BEFORE it gets to the membrane. Themembrane works at the IONIC level, ie, it REDUCES 'things' in thewater that are MUCH smaller than a 'regular filter' can.

To answer your question, we must first need to know WHAT it is youwant to reduce/remove from your water.

Its not really the hardness, its the total dissolved solids (TDS). Mostresidential RO membranes have a maximum TDS of 2000-2500 ppm. I've installedan RO for a customer with 2200+ ppm TDS using softened 126 gpg water. I addeda booster pump and the RO has been working for the past three+ years with onlyone membrane change. The average life of a membrane is 3-5 years with muchless TDS. There are different membranes for different applications - the trickis to get the right one and have the proper pressure.