RO water and Water Softeners

[Cuzco_Brew]

Hi All,

I have had a look through the primer on Brewing Water Chemistry and searched the forums, but I am struggling to understand the place a water softener has in treating brewing water.

I visited a local micro brewery the other week that uses one before their RO filter. Now I understand the need to use an RO filter after the water softener, as per this post https://www.homebrewtalk.com/f128/water-softener-ro-system-189329/.

However lots of the materials I have been reading list RO filters as a solution if you have very hard water. If that is the case, why use the water softener? Does it do something the RO filter doesn't?

Thanks
Zac

 

[ajdelange]

#4 in that thread explains why a water softener is often used before an RO unit. The RO unit will take out hardness but there is danger of calcium carbonate precipitation on the membranes. A softener simply replaces calcium and magnesium with sodium. Sodium and carbonate do not coalesce as readily as calcium and carbonate and so there will be no precipitation of calcium carbonate and the membrane will last longer (before it gets gummed up with whatever the limiting salt is after calcium carbonate has been eliminated).

 

[Cuzco_Brew]

Thanks. That makes sense. I did read your post in that thread, just didn't sink in. Much clearer now.
Cheers
Zac

 

[ricardo_agredano]

So what would the resulting water profile be for water that is run through a softener first, then an RO system? Would the Calcium Carbonate decrease? Sodium increase?

 

[VikeMan]

So what would the resulting water profile be for water that is run through a softener first, then an RO system? Would the Calcium Carbonate decrease? Sodium increase?

With a good RO filter, the answer is "close to 0 ppm" for all ions, the same (for practical purposes) as it would be without a softener ahead of the RO filter. The reason for using a softener ahead of an RO filter is to prevent shortened life due to clogging of the RO membrane.