How do water filters effect the minerals in water?

Question

In the particular section of the city I live in, the tap water has a poor taste. I use a Pur brand water filter (edit: activated charcol filtration) which improves the taste significantly (although it is still poor relative to bottled water).

For extract brewing, I purchase 6, 1-gallon water jugs from Wall-Mart. This adds roughly $10 to each batch.

I should hopefully begin All-grain brewing soon enough, and wanted to switch to filtered tap water in order to reduce cost.

I've been able to locate the mineral composition of the water for my section of the city.

By filtering my water through the consumer water filters, will the mineral composition of the tap water be altered, rendering the information I have gathered useless?

Edit -

In Brewing Classic Styles by John Palmer, he states:

Charcoal filtration alone will not affect dissolved minerals like iron, calcium, magnesium, coppe, or bicarbonate.... Most carbon filters are highly effective at removing chlorine and chloramine...

(pg 26)

Answer 1

Of course the filter takes out -roughly said- some of the character of your water, the bigger parts are filtered out. By just tasting the before and after results you will note the difference (or not). The smaller parts inside the water (e.g. other minerals and the added cleaners like chlorine) will not disappear. In some tap water you will still find the smaller parts of drugs people get prescribed, or the rest of other drugs without prescription :-). As a matter of fact all these components are not declared by your local water authority as legislation does not force them do declare beneath some values.

The second step is to look at the membrane of the filter, the finer the membrane the more minerals are sieved out. The more you take out, less lively the water will be. And naturally this has its effects on taste.

Here in Amsterdam we use normal tap water as the quality is good. A friend of mine is a professional crafts brewer, and he experiments also with filtering water for every new type of beer, so this is not a rare thing to think of. For demineralizing water often osmosis techniques are used, then you need to make labo analysis but for home brewing this way out of reach.

And don't forget to read the RELATED topics in the right bar of this page, there are many answers to your question.

Normal tap water should do. Or a combination of filtered and bottled water.

Answer 2

Not completely useless, but also not reliable. There are some expensive labs that can analyze your filtered water, but really it's the ratios that you will want to worry about with brewing.

A consumer carbon filter (or what have you) will take out some of the chlorine and minerals from your water, but I'm guessing the majority of mineral ratios will remain largely intact.

Get the book on brewing with water: http://smile.amazon.com/Water-Comprehensive-Brewers-Brewing-Elements/dp/0937381993/ref=tmm_pap_title_0

It's better to use filtered water in America due to all the hardness, chlorine and fluoride they put in the water, and from there you can add/adjust/experiment. If you use reverse osmosis, you definitely want to add to the hardness of your water for All Grain mashes as this strips much more essential minerals for an effective starch conversion and also for proper yeast growth.

Answer 3

It depends on the type of filtration system you use. Some just remove particles, some remove all minerals and basically leave you with RO water. I don't know which type you have.