Mother Earth news has plans and methods on about anything one wants to LEARN to do..:) You tube with the right key words can offer real good vids on DIY. Uncle used bleach or Javex in his well every 6 months for the rotten egg smell and treating ..
I used vinegar in the bush for 50 years and never got sick once 🙂 two caps in a 5 gallon pail water of vinegar..white or apple cider vinegar..two tablespoons daily with tea spoon tip, about, of baking soda to de acidify the vinegar then add 3 oz water or juice and drink it down..is powerful medicine and tonic..bath with it..wash hair..clean bites, cuts etc..body fungus..add to laundry. Wash floors..and preserve foods. Chlorine is death. Kills the gut flora..that kills you..candidiasis is no fun..yeast overgrowth..apple cider daily kills that too. Acidophilus, billion cells per cap, caps will keep you alive if not cure candida out right..flouride is death.:)

Berkey filtration systems are effective and have about the lowest cost per gallon I've seen. They have an optional fluoride and arsenic filter. Chlorine will out gas if you let it stand.
RO is good but strips dissolved minerals and needs high pressure. Berkey is gravity fed.

RO systems are amazing at filtering water - the best that I know. The key is maintaining them. In order to work at their best, RO systems should not have chlorinated water introduced - you need to start with non-chlorinated water or remove the chlorine first or risk serious damage to the RO membrane. The problem with RO systems is when they stop. You now have an environment with non-chlorinated water, lots of surface area (membrane) in a dark environment (RO chamber). Can you say BACTERIA! The only other challenge is not pre-filtering the water and having something small tear a hole in the membrane - you're pushing water uphill as it were so that pressure can send anything in the water through the RO material too.

I was in a major role in a commercial water purification system and getting the water clean was not the issue, but keeping the bacteria under control was. We did two things - always kept a trickle of water passing through the membranes at all time (it's when the water stops that the bacteria get to go crazy - and yes, I know it's a waste of water), and we had a holding tank afterwards that we injected ozone into. Making ozone is tricky - and can be toxic to humans. If you can harness it, it's the BEST in my personal opinion for dealing with bacteria. Bacteria absorb the ozone, like we absorb oxygen through our lungs into our blood stream (and ozone would be the same for us too). Ozone is an unstable molecule and when it breaks down, it literally blows up the bacteria from the inside out, and the ozone degrades back down to oxygen. You end up with clean, oxygenated water. You do have to monitor your water for bromide, as it is nasty when combined with ozone, but that's about it. Here's one explanation on it: http://www.ozonepurewater.com/the-ozone-process/how-ozone-works.html