I've been using a reverse osmosis for the last five or so decades, first in an apartment and then after getting this house. The RO water is nearly identical to distilled, is much easier to use and quite a bit less expensive. Both of these remove sediment, bacteria, chlorine, petroleum products, heavy metals and many other harmful substances. Any system that doesn't remove such things is not good. Healthy minerals are more easily found in food.
I installed a 5 stage system under the kitchen sink with a spigot at the top, but I only use 3 of the stages. A post filter should be removed as it puts loose carbon particles back in the water which tastes terrible and reduces the water quality. The system only needs 1 carbon block filter, but 2 of them can be used.
My system has the following:
A 5 stage system with 3 canister housings at the bottom ($125 or less on Ebay);
1x 1 micron sediment filter;
1x (or 2) 1 micron carbon block filters -- *do not use GAC loose carbon filters;
A spigot;
A 1/2" to 1/4" ball valve feed water adapter;
A
Filmtec 75gpd BW60-1812-75 RO membrane <-- most important;
A TDS meter - for checking the quality of the water.
A 5 stage system should cost less than $125 on Ebay. You will probably need to get the higher quality membrane and filters separately, which is no big deal as they are reasonably priced and well worth the extra expense.
Many RO membranes don't even remove 90% of the TDS (total dissolved solids), whereas the Filmtec removes 98+ percent. The city water here has an average of 528 tds, which is about 1/2 that at the tap (since there's also a 1 micron sediment filter in front of the house), and less than 10 (usually 5) where the water comes out of the spigot. Incidentally, this house was 10 years old when we got it many years ago, and the original water heater lasted for more than 28 years thanks to that sediment filter in front of the house.
I used a tank with a permeate pump with the system for many years, then removed the tank and simply fill up a couple of 1 gallon containers every morning. I did this because I feel it improves the water quality. It no longer sits in a rubber bladder, and I can let the spigot run for a couple of minutes to clear any encroaching water before filling the bottles.
If you do use a tank then I highly recommend also getting a permeate pump from Ebay, which costs about $55. An RO system usually has a ratio of 3:1 between reject and permeate (pure) water, but as the pressure in the bladder fills up that ratio can increase to 30:1 and much water is wasted. A permeate pump eliminates that waste and runs automatically on water pressure only.
This is much easier than it sounds, and the system can last a very long time with very little maintenance.
