Water, Water Everywhere but is it good to Brew?

Water accounts for the largest percentage of beer. Up to 97% in some cases. Water must then have an impact on the final flavor and quality of the beer produced. It is often overlooked, but I think should be considered when deciding what style of beer to produce.

Some of the reasons to consider the quality, mineral, and salt content (profile) of the brew water is different combinations bring out a more malty versus bitter character, as well as, providing a  healthy environment for yeast and enzymatic activity. First and foremost it should be potable and taste good from the tap. If there is a strong chlorine, sulfur or other off flavor, I would get some bottled water.

There are a few specifics to be aware of then when brewing with your tap or municipal sourced water. A great page on brewing water knowledge exists from Bru'n Water. Ill list a few of the basics:

1. pH - Water pH of the mash influences a number of factors in brewing including; fermentability, color, clarity, and taste of the wort and beer. The acceptable mash pH for brewing is in the range of 5.2-5.8. So the higher the starting pH (more alkaline) your water source, more of a chance will be an alkaline leaning mash pH. Acid or acidulated malt is sometimes added to bring mash pH down.
2. Hardness - is primarily due to the calcium and magnesium content of drinking water. Since there is a minimum calcium content desired in brewing water, moderately hard to hard water is typically desirable for brewing. 
3. Alkalinity - is related to pH, but is not a direct measure of it.  Alkalinity is a measure of the "buffering" capacity of a solution and its ability to neutralize strong acid and resist pH change. According to Bru'n Water "Alkalinity has a significant effect on beer flavor.  Beer flavor differs significantly from wine in large part due to the difference in alkalinity between beer wort and grape must.  The flavor of wine can be characterized as sweet and sour while most beers can be characterized as bitter and sweet.  The acidity of wine provides most of the balance to the wine sweetness while the bittering from hops provides most of the balance to the beer sweetness.  The alkalinity of grape must is typically negative due to its pH being under 4.3.  After fermentation, wine pH typically falls into the 3 to 3.5 range. The alkalinity of beer wort helps keep the pH of beer in the 4 to 4.5 range and helps avoid the wine-like reliance on acidity for flavor balance."
4.  Residual Alkalinity (RA) - RA is an indicator that is specific to brewing and is an important factor in defining the suitability of brewing water.  RA is calculated with the following equation when calcium, magnesium, and alkalinity are input as (meq/L) or (ppm as CaCO3). 
5. Minerals and Beer Styles - The historic beer styles that have developed around the world were sometimes the result of the water conditions present in that area. Typically, dark-colored beer styles developed in areas with high RA water and light-colored beer styles developed in areas with low RA water. 

Ithaca's Water Profile
Ithaca is supplied with water from two sources, Cayuga Lake and Six Mile Creek. The latter supplies the City of Ithaca. I am outside of the city limits and am supplied by Bolton Point Water from Cayuga Lake. The water is sourced directly from this glacial lake 400 feet out and 65 feet below surface. I called the water company directly to receive the following information from an engineer at the plant:

He also mentioned the water has a pH 8.3-8.2 and a level of hardness at 150 mg/L. Using the equation above for RA, I calculate an RA of 65.9.

Here is another style guide from Bru'n Water which also gives general style numbers to follow:

My brew water is moderately hard and alkaline. If I wanted to make the most often drunk American Lager beer, I might need to adjust my water a bit to come closer to the original Pilsen profile or the one above.

The EZ Water Calculator provides a handy way to punch in your profile and see if it falls within acceptable ranges given the recipe you plan to follow. It then suggests additions of various minerals and salts to adjust your water.

It looks as though my water is suited to styles darker and more bitter focused on hop charachter as I play around with typical recipes. I wont go into any more details on the adjustment of brew water as it is beyond my present scope. But this exercise gives a good start of which styles of beer my water will produce well.