Baltimore’s Water: The Goods

We’ve seen where it comes from. We know how it gets here. So let’s talk about Baltimore’s water. What’s in it? And what does that mean for Baltimore area homebrewers?

The Baltimore Department of Public Works publishes a water quality and a water content report annually. The first report demonstrates to the public that the municipal water is safe to drink. The second report provides a mountain of data for anyone interested in a in depth look at what’s coming out of their tap. DPW monitors the water leaving each plant and records monthly data points across 23 different categories.

Using the information from the 36 months beginning in 2015 and ending in 2017, we get a picture of what Baltimore are brewers are dealing with and how it changes over time. The water leaving the Montebello and Ashburton plants is:

  • remarkably similar; and,
  • remarkably consistent.

Brewing Water Report

As brewers, we tend to focus on a subset of water attributes that are known to have great impact on the brewing process and finished product. The 2017 averages (all measurements are in ppm except pH) for those brewing centric categories are:

Montebello Ashburton
2017 Low High 2017 Low High
pH 7.8 93% 102% 7.8 98% 103%
Hardness (CaCO3) 116 96% 104% 80 93% 104%
Calcium (Ca) 30 94% 110% 21 93% 112%
Magnesium (Mg) 9 94% 107% 6 97% 106%
Sodium (Na) 20 88% 113% 19 91% 107%
Sulfate (SO4) 17 85% 122% 13 91% 135%
Chloride (Cl) 53 91% 123% 42 98% 103%

Baltimore’s water is low-moderate in hardness and is relatively low in flavor ions (chlorides being the exception). Ashburton water is a touch softer than Montebello, but across the board the water content is largely the same. All told, it’s a great starting point for brewers.

Mr. Consistency

Month-to-month the water changes very little, drifting off its averages about 5% in either direction. Further, when we look year over year, the levels recorded in the data set are quite stable.

2015 2016 2017 3-Year Avg Std % Std
pH 7.8 7.8 7.8 7.8 0.01 0%
Hardness (CaCO3) 106 106 116 109.2 5.51 5%
Calcium (Ca) 28 29 30 28.9 0.87 3%
Magnesium (Mg) 8 9 9 8.7 0.37 4%
Sodium (Na) 24 21 20 21.7 2.04 9%
Sulfate (SO4) 20 16 17 17.9 2.08 12%
Chloride (Cl) 64 52 53 56.3 7.08 13%
2015 2016 2017 3-Year Avg Std % Std
pH 7.8 7.7 7.8 7.7 0.05 1%
Hardness (CaCO3) 73 74 80 75.5 3.55 5%
Calcium (Ca) 20 21 21 20.5 0.67 3%
Magnesium (Mg) 5 6 6 5.8 0.32 6%
Sodium (Na) 20 19 19 19.2 0.53 3%
Sulfate (SO4) 12 12 13 12.5 0.90 7%
Chloride (Cl) 43 41 42 42.0 1.04 2%

So now that we know what’s in it, what does it mean?

A Tale of Two SRMs

If you’re on municipal water it doesn’t matter much which plant you are drawing from when managing your mash pH. Let’s examine the stories of two very different beers. In both examples, we’ll assume a batch sparge system with 75% efficiency & typical volumes, a target of 5 gallons into carboy, and an original specific gravity reading of 1.050; some fairly common targets and methods.

We’ll start by brewing a pale beer, say a pilsner. For our girst we’ll use 100% Pils Malt and treat our Baltimore tap water with only a Campden tablet for Chlorine. How much Acidulated malt do we need to hit a a target mash pH of 5.3?

  • On the Montebello Supply we’d need 5.1%.
  • On the Ashburton Supply we’d need 4.9%.

Now let’s consider the other end of the spectrum. A stout with a grain bill of 80% UK Pale, 10% C80, & 10% Roast Barley. How much Acidulated malt do we need to hit a target mash pH of 5.3?

  • On the Montebello Supply we’d need 2.1%.
  • On the Ashburton Supply we’d need 1.8%.

The amount of Acidulated malt required for each beer is almost identical regardless of the municipal source. Both sources are comparably low in Calcium, Sulfate, and Chloride, making it fairly straightforward to adjust the flavor ions using Gypsum (CaSO4) and Calcium Chloride (CaCl2). Additionally, if the water isn’t soft enough for your brew diluting with to a 1:1 ratio with distilled water will approximate the famous Pilsen water profile to a surprising degree.

Wrapping It Up

All considered, Baltimore’s municipal water is an asset to any local brewer and, with minimal effort, can be tweaked to a variety of profiles. Perhaps it is no wonder that Baltimore developed a rich brewing tradition rapidly after founding.

No matter how you decide to manage your water on brew day we hope this series of articles has shed a little light on the history, operation, and content of the Baltimore municipal water supply. The water here has the potential to make great beer.

Cheers and happy homebrewing!


  1. Baltimore tap water contains low levels of free chlorine. There are many strategies to remove it.
  2. Baltimore occasionally pulls water from the Susquehanna during times of drought or excess demand. There may be intermittent periods when the water profile differs significantly from the data shown here.
  3. This data is taken from water leaving the filtration plants. While many of our club members report it as being consistent with water content tests from their home faucets, getting a water report from your tap is the recommended way to calibrate your brewing water calculations.