It’s the true beer-lover that pays close attention to that essential fourth ingredient of beer: water! Brewers know to use good hops, yeast, and malt, plus the best water available to make a really successful beer. For homebrewers especially, there are plenty of reasons to bypass basic tap water and opt for an in-house water filtration system. Whenever you’re creating a new, custom beer recipe, water is the first ingredient you should be thinking about. This is equally true for extract brewing. Even if you’re working with a prepared ingredient kit, your brewing water will greatly impact the flavor profiles of your beer. Water makes up about 90% (and higher) of any beer, so your water’s quality is going to add a distinct taste to your brew. It’s important to keep in mind that our municipal water, or tap water, has varying levels of “hardness” and chlorine added to it. These attributes are not ideal for beer. Not to mention the fact that your own unfiltered water may have high-iron levels, sulfuric smells, and microbes. Frankly, your tap water isn’t good enough to use for brewing. For extract brewing it’s best to use reverse osmosis (RO) water. These filtration systems are great because a lot of people use them already for their home’s drinking water. If you have one installed—great! You’ve got a water chemistry that’s basically a “clean slate” for brewing. It’ll work great for kit beer, and be an excellent foundation for designing your own beer recipes, too. RO systems work to make your water pure. They can remove the chlorine from your tap water (because chlorine is added as a disinfectant at the water treatment plant) and make your drinking water clean. That means no more chlorine taste or smell—a smart move for homebrewers. A common brewing error is using unfiltered, chlorinated tap water. Doing so can create an off-flavor of “medicinal chlorophenol,” which is a homebrewer’s mistake of letting chlorine combine with the phenols from your malt and yeast. Another misstep for homebrewers can be water hardness. The preferred calcium levels for brewing tend to fall in the 100mg/L range. So if your home’s water is already hard (anywhere from 60mg/L to high extremes of over 170mg/L) you might want to use soft water (which has calcium levels below 60mg/L). That way you can control your desired calcium level with additives and not run the risk of having water calcium levels that are already too high for your brew. Working with extremely hard water can disturb your extract brewing measurements. So it might be better to add a water softener to your home’s setup along with an RO unit for filtration. These whole house water systems are also great for your appliances, doing laundry, cooking, cleaning, and bathing—basically any “water” activity in your home benefits from these systems, not just brewing. When it comes to the best water for homebrews, it’s really about using the best water in general. With the right softener and filtration system in place, your home—and your home brews—will be much better off.