RO vs. Distilled water

[Spurtrax]

Is water run through a RO water filter system the same as distilled water?

My water comes from a well and is moderatly hard. Perfect for dark beers and I cut it a little with distilled water when I go lighter. I have never worried much about it but I saw a RO system on Craigslist pretty cheap.

Will the RO reduce the hardness of the water to the point it is pretty neutral and I would need to build every water profile from scratch?

Thanks,

Spurtrax

[BDawg]

yes, the net effect is pretty much the same. You'll have to rebuild the water from scratch.

[ajdelange]

Is water run through a RO water filter system the same as distilled water?

Technically, no, but practically speaking for brewing purposes, yes. Distilled water has had all the ions (except for hydrogen and hydroxyl) removed. RO water has had 90 - 99% of the ions (rejection depends on the particular ion) removed.

Will the RO reduce the hardness of the water to the point it is pretty neutral and I would need to build every water profile from scratch?

It removes not only the hardness producing ions (calcium and magnesium) but all the others too. If your water is hard it is a good idea to soften it before feeding it to an RO system. You won't get better water but the membranes will last longer (won't get crudded up with calcium carbonate).

You will need to supplement the minerals in RO water but you shouldn't worry about profiles except in the broadest sense e.g. brew Pils with water low in mineral content, brew Export with water high in mineral content, brew Burton ales with water high in sulfate.

There is a set of guidelines at
http://www.homebrewtalk.com/f128/brewin ... er-198460/

[spiderwrangler]

I saw a RO system on Craigslist pretty cheap.

Should Spur be concerned about buying an RO system on craigslist? What sort of things would likely have to be replaced/purchased to make it functional?

[ajdelange]

Personally I'd be concerned about buying anything from Craig's List or Ebay but I know lots of people who do. I once met a couple at a party in a pretty upscale neighborhood who made their living buying and reselling on ebay. Strange world we live in.

Anyway, an RO system consists of a particulate filter, an activated carbon filter, a polish filter and the RO membrane. The rest is tubing and connectors to hook this stuff together, a pressure tank to hold the water produced and a little faucet to dispense the water and provide the air gap required by most plumbing codes to be in the concentrate path. The filters cartridges and membranes obviously have finite lives. If the water being put through the system contains chlorine/chloramine the carbon filter life will be limited. If the water is very hard the membrane can become encrusted with lime.

When a system is installed it is supposed to be sanitized with bleach so I suppose there is a chance of bacterial infection.

The would be buyer can do some checks such as putting it on a chlorinated water sytem and sniffing for breakthrough at the output, looking at he pressure across the particulate filter and checking the permeate production rate and its TDS (conductivity). He could then do the sterilization procedure (if the manual comes with the kit) and probably be OK.

I have given old systems to other brewers but those guys got gear whose history they knew completey and the price was right so they risked nothing if the things failed a week after they set them up.

[mordantly]

my 5 stage has held up pretty well in 1.5 years of light usage and i have over 300 RH! i have a high-rate membrane but i flush more waste so it will be interesting to see what it looks like when i need to change the pre-carbons and pre-sediments (5 or 10 micron).

RO works great for washing my faucets off, my ninja 500, etc when i don't want water spots.

[snax]

From time to time Costco has reasonably priced 4 stage RO units, and nowadays any NSF approved unit must have a performance indicator for the reverse osmosis membrane. A preliminary stage of carbon filtration is necessary to remove disinfectant residual of chlorine or chloramine, which can damage the RO membrane.

Contact time, size of the carbon filter, and flow rate impact removal rate for chlorine and chloramine. Good idea to test the residual with strips both pre- and post-treatment if you don't want to use any potassium metabisulfite.