Water makes up over 90% of beer. Yet, for many brewers, its origin is something of an afterthought. Whether you’re a homebrewer or running a brewery, understanding where your water comes from and how it changes can be the difference between your best batch or a bad batch.

Groundwater, Surface Water, or Well?

Your brewing water typically comes from one of two main sources:

  1. Municipal (city) water
  2. Private wells

1. City Water Supply

Most breweries and urban homebrewers rely on water from municipal distribution systems. Municipal water is treated to meet EPA safety standards, but this treatment can significantly affect your water profile.

This water is drawn from one of two sources:

  • Groundwater: Pulled from aquifers, this water has filtered through layers of rock and soil, often giving it higher mineral content and natural hardness.
  • Surface water: Taken from lakes, rivers, or reservoirs, this water typically has lower mineral content and can vary more based on rainfall, runoff, and temperature. It may also require more chemical treatment (chloramine or chlorine).

2. Private Well Water

Some rural brewers and farmhouse-style operations use their own wells. Well water is untreated and often contains high levels of calcium, magnesium, iron, or sulfate, depending on the local rock and soil composition. While this gives some brewers a unique water profile, you are the only one monitoring it. You’ll need to test your water regularly to ensure your water is suitable for brewing.

Seasonal and Operational Shifts in City Water

Even if you rely on city water, your water chemistry isn’t always consistent. Many cities use a blended water system, meaning they use both surface and groundwater, depending on seasonal availability, drought conditions, or maintenance. Even during instances of maintenance or construction, the city might change your water supply without warning.

Municipalities aren’t required to inform customers about temporary source changes unless there’s a health concern. For brewing beer, even small shifts in your water profile can change flavor, haze stability, and mash performance.

What Brewers Should Do

  1. Know your water profile. To notice changes in your water quality, you have to know your water profile. This will give you a starting point to check for any changes over time.
  2. Test regularly. By using affordable DIY Test Strips, you can monitor your water quality every time you brew to make sure that your water source hasn’t changed, preventing you from ruining a batch.
  3. Keep records. Log every water test to monitor seasonal changes in your water chemistry. If you are on city water and notice any major changes, you can reach out to your local distribution system to ask if they have changed sources.

Summary:

Water is the foundation of every beer, yet many brewers overlook where it comes from—and how it changes. Whether your water is sourced from a city distribution system or a private well, its origin directly affects your beer’s flavor, clarity, and fermentation. Municipal water can come from surface or groundwater sources, each with distinct mineral profiles. Private well water will also carry with it a distinct mineral profile due to local geology, but unlike municipal water, it requires personal oversight.

Seasonal shifts, maintenance, and droughts can cause unexpected changes in municipal water supplies. To maintain consistency in your brews, it’s critical to test your water regularly, track results, and adjust your recipes accordingly. Knowing your water profile isn’t just smart, it’s essential for making sure that every batch is your best batch.