Some plumbing codes do not accept a check valve as a cross-contamination device. I prefer an air gap faucet as there is no down side to one.

Every filter will effect taste to some degree and more discerning palettes will pick up the taste difference right away. If that filter interests you then give it a try.

I have a conventional 4 stage RO... sediment, carbon block, membrane, GAC polishing post filter and I find the water great.

FWIW.....my RO water comes out at 5 or 10 TDI depending on location. Personally, I have always preferred Hinkley & Schmitt's bottled water which is, basically, RO water with added minerals and reads about 25-30 TDI. Other vendors' waters have about the same TDI but taste different to different palettes. Many people think RO water tastes flat, kinda like distilled water does.

Many people -- including me -- prefer this minerals-added "drinking water" version taste-wise. All I can say is I much prefer my RO water to unprocessed tap water at my location because we have miserable tasting tap-water. Exactly what your processed water will taste like after adding this additional module is something only you can evaluate.

I agree with justalurker....give it a shot and see what you think.

At this moment I'm considering upgrading my own Kinetico RO unit (18 years old and working OK, except no more parts) with the new K5. My intention if/when I change over is to try their mineral-adding module also. However, I have no idea -- and they don't either -- whether I will like it. Individual taste at work. Kinetico's module costs about $90 so it's a serious consideration. It will need to be good for me to continue using them.

I have heard that one downside of the air gap faucet is that some can be noisy. Does anyone know what features might minimize the noise? I am looking for a lead-free faucet with a low profile. I would like a brushed nickel or stainless steel finish. Thanks.

The air gap faucets are not noisy it's the drain line from the faucet connected to the drain pipe in the sink.

The water drops from the drain line down the pipe and hits the water at the trap... that's what is noisy.

Do you hear this water only when there is a "clog" ?

In my experience it mostly isn't there at all. The waste water just trickles silently down the tube. Occasionally, I hear the dripping sound. Have never been able to determine why sometimes yes and other times no. However, the only time it does it is when the unit is making RO water which in turn generates the waste water. When the tank is full and the unit shuts itself off, there is no sound -- which is most of the time.

The noise is a possibility when the RO is making water. Some people can't hear the noise, others can. Some people get accustomed to the noise as kind of a background noise and ignore it, others it can drive crazy. The noise can be mitigated or eliminated depending on the expertise of the installer.

The number of ROs sold indicates to me that the noise is either dealt with by knowledgeable installers or is a no big thing thing.