Water sources

Proper selection of the raw materials for brewing has a considerable impact on beer quality, and water is no exception. Brewers have options for sources of the water ingredient, including RO water and tap water. Some brewers may wish to blend two water sources to achieve a more desirable mineral profile. For example, tap water can be blended with RO water to reduce the alkalinty, perhaps achieving a proper mash pH without needing to further adjust the water minerals or acid/base. Simple blending calculations apply. However, in most cases, it's easier to simply use RO water if you have access to it.

Reverse Osmosis (RO) purified water

RO water contains little-to-no minerals (including chlorine and other unwanted chemicals). Therefore it is an excellent choice for brewing water because it allows the brewer to have full control over the mineral profile, offering maximum flexibility. RO water can either be purchased in reusable jugs, or produced on-site with a RO purification system. This is great for any scale of brewery, from home brewing all the way up to macro level. Whether you buy the water or produce it yourself, you should verify the purity with a TDS meter (e.g. RO systems in grocery stores are not always well-maintained).

Distilled or deionized (DI) water

Distilled and deionized water contain no minerals, and like RO water, they are very flexible options for brewing. However, unlike RO water, distilled water requires a lot of energy to produce, and typically cannot be readily produced on-site. Therefore it may not be an economical or practical option. Deionized water is basically RO water that has gone through an additional stage to remove any ions that got past the filter membrane; this is overkill for brewing since RO water generally contains a negligible amount of minerals without needing a DI stage. RO water is usually a better choice than DI or distilled water.

Tap water

Tap water contains dissolved minerals, commonly around 100 to 400 mg/L, although some tap water sources can be 1000 mg/L or more. Brewers need to know the level of each individual dissolved mineral in order to use the water for producing quality beer. To obtain this information, usually a sample of the water needs to be sent to a lab for analysis (see Water report), although sometimes a municipal water supplier provides the necessary information (termed Secondary Maximum Contaminant Levels). Unfortunately, the mineral content of tap water can fluctuate between day and night, from year to year, and between seasons (especially surface water, e.g. from rivers or lakes). If you live in an area where diverse sources of water are used to supply one supply zone, your water may vary greatly from one day to the next. TDS testing is very helpful for monitoring overall mineral levels. If there is a change in the water minerality, simple and inexpensive testing equipment for alkalinity and hardness and can be useful for adjusting your water treatment without needing another laboratory report. Tap water from a municipal water treatment facility also contains chlorine and/or chloramines. These chlorine compounds must be removed from brewing liquor. If your home uses a "water softener", the water it produces is typically not suitable for brewing (brewers want calcium, not a lot of sodium).

Bottled spring water

This is basically the same as tap water. Companies extract water from multiple sites, each of which has different levels of minerals. All of the above information about tap water applies, i.e. spring water contains minerals, you will need at least one water report, and test the TDS of every bottle to verify consistency. You'll need another water report if the TDS is substantially different, because that's a good sign the water came from somewhere else. There are also possible environmental and social concerns associated with the extraction of large volumes of ground water for bottling, and the excessive use of plastic. With all of these issues, bottled spring water is not a great option compared to RO water or tap water.

Untreated water

Rain water or any other untreated surface water contains contaminants and therefore it is not considered safe to drink without appropriate treatment, which is beyond the scope of this article. It is also ill-advised to use yellow snow for brewing. We also do not condone blending blue pond water with yellow snow as a means to make green beer compliant with the Reinheitsgebot.

See also

• Water
• RO systems
• TDS testing
• Water report
• Remove chlorine from tap water