Hi there,
I had a big post explaining how the RO works and such but lost it when my computer hiccupped grrr..
I have made a small image to help with this discussion.
I understand your concerns about bacteria and contaminants entering your purified water. With all the stuff going on these days with driking water it is bound to come up
You seem to think that the purified water comes in contact with teh pre filtration side of the Membrane. It doesn't. Save you having a tear in the membrane. With proper use and maintenance this shouldn't happen. The purified water never passes through any of the parts of the system on the dirty(or pre-filtering) side. after it passes through the RO membrane it is not allowed to be forced back through the membrane due to a check valve in place to stop this.
To tap water enters the pre filter, pre carbon then to the RO membrane. Once it is forced through the membrane the bacteria etc remains on that side of the system. If you do not check and replace the parts of this system then you can have the contaminants enter the purified side. I know that I make sure that all my systems with my reef are working properly. I one fashion or another. This is no different.
I have been in the navy for 11 years and the RO systems used on board the newer frigates for water purification are a great system. In my 11 years I have never heard of any problems or anyone getting sick due to water on board. When we enter into a foreign port where the water quality is suspect the water supplied is passed through the ship's own RO system. I have drank many many gallons of that water over the years. We did that in Thailand and other ports they weren't quite positive about the water quality. I have sailed on three of those frigates and have close friends on all the others.
I still say that they are safe. Yes, you should check and verify that your system is working properly. And that you do proper maintenance. That is a given. But I would much rather drink the water coming out of that filter than what is coming out of the taps. Even with the cities working to keep our water clean for human comsumption look how many cities have problems and have to shut off the water. The RO filter is an added protection in my eyes. Use it properly and it provides you with an added level of security.
I can see Mr Bingams concerns but once again it comes down to keeping your equipment working properly. He even stated that. Keep an eye on it. As for the UV and the Tank Sterilizer I don't see them adding anything more. Once again unless you have misused or over extended your RO membrane the particles and bacteria will remain on the pre filtration side of the unit. They are selling these devices by playing on peoples fears of getting bad water. To make an extra buck. If you want those. go for it. After seeing RO systems in use for a few years, I'll trust what I am using. And keep it in good shape. Just like any other investment I make.
If there were problems with these systems you would hear about it. So many people are ready to sue each other due to false claims etc. I know for a fact there are people out there who aren't as fastidious about the maintenance of these things or anything and you don't hear abotu anyone getting ill with the mis-use. Once again I will trust what I have experience with and used for a long time.