You can also reduce the mineral content in your brewing water by mixing RO with your regular water. If you wanted to reduce it by half, for instance, you would mix your regular water with 50% RO water.
It's also useful for steam irons, topping up car batteries, topping up aquariums water (fresh or salt water), and anything that you might use distilled water for. You might even like coffee or tea made with it.
Make sure you have a way of monitoring the RO water to know when it's time to change the RO membrane filter. When you change the first charcoal filter, put the second where the first was and the new one in the second position.
You can also reduce your waste water quite a bit, if that's an issue, by using a permeate pump in place of the valve that comes with it. It also improves the pressure a bit and makes it produce RO water faster. It will make a small amount of noise when you draw water.
There are some people who hook theirs up to the hot water supply plumbing because it will produce water faster. It reduces the life of the membrane, though, and is not what is recommended by any manufacturer of RO systems that I know of.
Mine has a sediment filter, two carbon block filters, the RO membrane, and a DI (deionizing) filter (which I use only for aquarium water). I think it has a 6th stage filter also of some sort also, and the pressure tank, of course. I use a TDS meter to monitor how efficient the RO membrane is, so I will know when it's time to replace it.
