What does a filter actually remove?

[CascadesBrewer]

I see a lot of different filters out there, and I wonder what they actually remove and how that impacts brewing water. For example, when I brew small batch extract batches I use water filtered through my Brita pitcher (which I think uses an activated charcoal filter), and I see people that use/recommend an "RV Filter" (which I think most are charcoal filters).

My girlfriend has a "ZeroWater" pitcher filter (https://www.zerowater.com/). It comes with a
TDS reader and the resulting water measures at zero or low single digit numbers. Does this indicate that it is removing all minerals like calcium, sodium, chloride and sulfate? Is the resulting water equivalent to RO water?

For my 5 gal batches, I use unfiltered tap water treated with campden and adjusted for target mineral levels and pH. As I understand, my tap is treated with Chloramine. Would there be any advantage to using some type of filter?

 

[Silver_Is_Money]

TDS ~= Ca + Mg + Na + K + Fe + NO3 + Cl +SO4 + (HCO3-/2)

Therefore a TDS of near zero means that the filter is removing calcium and magnesium ions.

 

[mabrungard]

Some of those 'pitcher' filters have deionizing resin beds that remove both the cations and anions. They certainly work, but if the water has much ionic content, they'll be exhausted quickly. With the TDS meter monitor, the pitcher manufacturer helps you to know when the resin is exhausted and when you can buy another expensive filter from them. I ought to be in that business!

 

[CascadesBrewer]

What about the typical RV Filter type items? My understanding is that they remove "organic" material (would I have much of that in tap water), maybe they remove chlorine, they may or may not remove chloramine, and my understanding is they don't remove other ions.

This is partially because I am curious about filters, and partially because my girlfriend brews small batch all-grain using filtered water from her ZeroWater filter. It sounds like I should suggest she adjust her water as if it was RO.

 

[mabrungard]

What about the typical RV Filter type items? My understanding is that they remove "organic" material (would I have much of that in tap water), maybe they remove chlorine, they may or may not remove chloramine, and my understanding is they don't remove other ions.

This is partially because I am curious about filters, and partially because my girlfriend brews small batch all-grain using filtered water from her ZeroWater filter. It sounds like I should suggest she adjust her water as if it was RO.

Yes, for brewing with a deionizing filter like those, it may be best to assume that the water is a blank slate. But with that, you should also do an easy check of the water quality with a TDS meter. Be sure that it's TDS is nearly zero.

A carbon filter has the ability to remove many organic compounds by adsorption and it destroys chlorine compounds via catalytic destruction. But it largely leaves all ionic content unchanged. There are a few heavy metals that it can retain, but that's the exception.

 

[Lefou]

When I first started to brew I used city tap water through my refrigerator's carbon filter.
My beer had that medicinal "Band Aid" flaw that was magnified by the extra Cascade hops I added, so I changed up my water game. If you can do a 5gal brew on purchased water and ingredients for less than $30, you're coming out ahead - especially if you re-use yeast.
*Lefou's Dirty Little Secret* .... my brewing water and drinking water are NOT the same and I drink more beer than tap water.