Reverse Osmosis

[Leann ull]

Is it as high as that I thought it was 2 litres for 1 litre RO I'm on a well so good in any case.
Anybody have an issues with them being dormant say if you only used it once or twice  a month?
I reading you have to use them consistently to be effective

[Leann ull]

Think I'm gonna try a few brews with commercial Ro stuff just to get my eye in before I pull the trigger

[imark]

I didn't buy yet. I only want it for cutting my water so as long as it strips out 99% of the relevant minerals it will be fine.
Curious about the point you make about regular use though as it won't get used very often. If its not effective when I crank it up once a month it's kind of pointless.

[Sorcerers Apprentice]

I'm only going to use the RO unit for brewing, and in this case the 3 filter unit is all that is needed. The extra filters are only necessary if you intend to collect the treated RO water in an expandable container as the rubber ball in which the water is collected can leave a rubber taint to the water. The final extra filters are to remove this taint. In my case I intend to collect directly into the HLT.
I have changed from using 100% Leixlip tap water to 50:50 Pet Shop RO:Tap Water based on the recent water test results. With a small addition of Epsom and CACL and my beer flavour has improved. dramatically.

[auralabuse]

I'm curious as to how the ro system dumps water at a ratio of 4 to 1. I thought it just forced the water through progressively tighter filters. Could you be talking about a softener?, I ask this coz I haven't got a clue

[imark]

As far as I can see you can reuse the dumped water. It's gone through three filters by that point so would be devoid of chlorine etc. Just a bit harder.

[Leann ull]

Some of the five filter don't have big rubber balls and 4 and 5 are taint and chlorine
I need more research!

[Dr Horrible]

I'm curious as to how the ro system dumps water at a ratio of 4 to 1. I thought it just forced the water through progressively tighter filters. Could you be talking about a softener?, I ask this coz I haven't got a clue

RO filters don't work like the standard 'dead end' filters you'd be used to, if you tried to filter at that small a scale you'd just end up blocking the filter. What they do instead is recirculate the water across the face of the filter at high pressures and speeds. This means there's still pressure to drive the small molecules like water through the filter but the high recirculation means that the larger molecules aren't left to stand still and block the filter. This means though that the amount of large molecules recirculating gets higher and higher as more water migrates through the filter.  If you keep on recirculating the same water the concentration of the unwanted larger molecules in the recirc gets too large and they'll start to force their way through the filter which you don't want, so that water gets dumped and fresh water is fed in to keep performance going.
Hope this is somewhat clear! The rule of thumb for large systems is 2:1 like was mentioned above. 
I've never seen anyone at large scale use this dump water for anything, I don't have a technical reason, just that everyone seems to be suspicious of it.
Personally I prefer a more low tech (and cheaper) approach.  Rainwater is a completely soft easily obtainable source of water. However it can get stagnant in a butt or pick up something off the roof on its way to the butt, but if you filter this water through a ceramic 0.2micron filter (http://www.amazon.co.uk/gp/product/B00519AM5S?psc=1&redirect=true&ref_=oh_aui_detailpage_o06_s00) you'll remove any bacteria it may have picked up and get yourself an environmentally friendly source of brewing water.  I've used this for the past 12 months and have been very happy with the results, there's a little bit of manual labour involved in filling and emptying the filter but I don't mind this as it reminds me I'm going to be brewing soon!

[Leann ull]

I really wouldn't recommend any rainwater from a roof as there are nasty paint colour and uv treatments on the slates, even the natural ones, the gutters can be aluminium or PVC with a lead content although most now are calcium zinc, again not food approved and your green collection drum is the absolute worst thing for potable water apart from the fact that it's the collection pool for any heavy metals from the above.
Great for cooling not for drinking!

I'm not even sure if you got a food grade sheet out and caught rainwater directly as I  was reading recently about the quality of rainwater and what it picks up from atmospherics falling to ground in urban environments from diesel particulate, not as bad as the above but another factor and it's the "scrubbing" through soil and rock that removes a lot of airborne nasties.

[Dr Horrible]

I take your point about the collection drum (I use a food grade container to collect) but would have to query your assumptions about the rest - I don't believe that there's going to significant amount of transfer from a roof to the water in the minute or two it takes to get across a roof - I've never picked up anything when testing anyway.   Given I'm in a fairly rural location fuel contaminants aren't a major concern to me.
I don't want to derail the thread about RO as it's an interesting one, just wanted to point out another option. RO is very good but expensive and also needs monitoring as well, at the pressures they run at, a slightly damaged seal or filter can let everything pass through. I wouldn't consider it a 'fit and forget' option either but then nothing is really.

[Leann ull]

The issue with heavy metals is that they are cumulative and will build up in endocrine and polymer resin vessels irrespective of their initial approvals.
Residual or lying water on roof or guttering picks up leachate that migrates to the surface and becomes concentrated and then washes into container.
My comments came from info on a roofing project I was working on for Cloughjordan Ecovillage 7 or 8 years ago where they were looking at plastic recycled roof tile options.
Really not something we should encourage for traditional roofing systems tbh.

Coming back to RO, yep the more I look into this not sure use once a month will keep it 100% effective.

[imark]

That's a dose. I can't be driving for half an hour for a €4 drum of water. 😥

[Ed]

I just checked the pH of the RO water I picked up, and I'm just thinking I may have incorrectly calibrated the meter...

i used the RO water to calibrate it, but when i was reading about it earlier, it says the pH is normally 5 - 7 for RO, so I'm guessing that wouldn't be the best thing to use with the powder to make up the buffer solution? it's telling me the pH of the RO water I have left in the container is 8.3???

[imark]

You can get bottles of distilled water in a motor factors.
I would have thought the calibration addition is just a pH buffer though so I'm surprised it's that easily swayed by your water.
Are you following the calibration instructions properly? Is the pH meter a piece of junk? You could probably do with some second source as reference.

[Ed]

You can get bottles of distilled water in a motor factors.
I would have thought the calibration addition is just a pH buffer though so I'm surprised it's that easily swayed by your water.
Are you following the calibration instructions properly? Is the pH meter a piece of junk? You could probably do with some second source as reference.

Quite possibly is junk - I might just get some pre-made buffer solution and test it \ recalibrate it.