I am considering buying an in-line reverse osmosis (RO) filter for our new house, as #1, I like to drink good water, and #2, I like to brew with good water. Somewhere in between those two, however, is I also like to COOK with good water.

I feel like a water report is like a snapshot of a single point in time, when the composition of the municipal water can change throughout the year to match rainwater pH/composition, so I'm likely going to start building from RO up.

I can't seem to find any information on the webs about cooking (baking, bread-leavening, etc.) with water that is good for brewing, that is, good for brewing after some salt/acid/base additions. The last thing I need is to be adding CaCl to my wife's shortbread cookies.

Will plain RO water work for cooking as well as brewing, or will I need to make similar additions?

  • I'd say to just look at what the recommendations are for distilled water, as it's functionally equivalent, but there seems to be a lot of conflicting information out there.
    – Joe
    Nov 1, 2013 at 20:39
  • From the wikipedia article: "Household reverse osmosis units use a lot of water because they have low back pressure. As a result, they recover only 5 to 15 percent of the water entering the system." That sounds awful.
    – Cascabel
    Nov 2, 2013 at 1:48

2 Answers 2


A good RO system costs about $100,000 as advised to me by a hydrologist. You may be better off with a good 3-filter (10 micron) setup. RO is usually used for high volume of consumed water and doesn't get everything out (unless you have the $100k system).

Before you spend the money, I would recommend consulting a local hydrologist and lab about other local tests they've performed over the recent times and what they've found in the water.

You can also walk into the nearest Starbucks as ask them about the filters on their lines. Regardless their coffee taste, they are usually strict about their water being good. You may be able copy their set up and be happy with it.

As far as cooking and brewing with 'over filtered' water goes, it may be a better problem to have than unwanted stuff in the water left behind. Some bottled waters such as Dasani have everything removed, then they add back some minerals to satisfy taste profiles [sales].

For cooking and brewing, you're unlikely miss the taste of the minerals in the water and more likely be happy about crispness.

  • From my experience working in a Starbucks, the people in a Starbucks will almost certainly have no idea what their water filter setup is. If you manage to strike up a conversation with the tech who Starbucks Corporate sends out when those filters stop working, that person is who you want to ask.
    – A_S00
    Jun 21, 2021 at 7:04

Any water that is safe and tastes good for drinking (and is not highly mineralized) will perform well for cooking and baking, except possibly in the most unusual and fringe circumstances which I will not venture to guess at.

Most mineral waters will work most of the time as well, but who wants to pay the cost?

  • RO water doesn't taste good for drinking ... it's similar to distilled water, but a different process. It just tastes ... flat. (which is why he's mentioned adding salts back in ... it actually dilutes the salts in your saliva, making it taste bland)
    – Joe
    Nov 1, 2013 at 20:34
  • 2
    @Joe If that is the case, the implication of doing so because the OP likes good water for drinking is misleading.
    – SAJ14SAJ
    Nov 1, 2013 at 20:43
  • Indeed, this question is based on the iffy premise that the best water is mineral-free (or with minerals you've added), but we may as well answer it anyway. I guess it's always possible that the OP or someone else has water with a really strong, hard to filter mineral taste.
    – Cascabel
    Nov 1, 2013 at 20:52
  • 1
  • Many people claim that it is the unique mineral content of the NYC water system that makes NY Pizza and Bagels so unique. blogs.wsj.com/metropolis/2010/10/26/…
    – BJ Safdie
    Nov 4, 2013 at 4:06

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