David answers:

The reverse osmosis process just removes the impurities in the water. There is one case where the pH could potentially change a bit – if the water has had its pH raised by adding something like “soda ash” -used by some city water supplies to bring the pH up to 7 or above.

It is possible that part of the reaction that took place to raise the pH could be undone by the reverse osmosis process in some municipal water supplies.

I have an RO system in a city that DOES use soda ash to raise the pH. I tested the water straight from the tap and again out of the RO system – I did not detect even a 0.1 change in pH -so I can’t say its impossible, I’ve read it can happen, but I have never seen it happen and I have testing equipment that is sensitive enough to detect it.

David answers:

I think what doodlesodindo meant was to “Get a Life Ionizer”.

They have under counter water ionizer units with a UV light technology option that can be paired with a 3, 5 or 6 stage reverse osmosis system. See links below.

David answers:

It’s quite simply chemistry. Although I wouldn’t put a stamp “don’t use” on ionizers, as some of them can perform well, the reason against ionizers and water electrolysis is simple. In electrolysis, positively charged elements are removed from water, and leave larger concentration of negatively charged ions. The problem is that most metals are also negatively charged. So electrolisys effectively increases concentration of dangerous metals such as lead and mercury in water, sometimes even 2 to 4 times. You would need a metal removing post-filter for an ionizer to do what it claims to do, and most ionizers just don’t bother having it.