Here’s Why You Should Never Use Tap Water to Brew Coffee At Home

Not everyone treats coffee like an art form. Some of us just want a cup that gets the job done—no fuss, no frills. But even the most laid-back coffee drinker can’t deny that taste matters. And when you consider that coffee is roughly 95% water, what you brew it with isn’t just a detail—it’s the main event. Tap water might seem like an easy, no-cost option for brewing coffee at home, but before you let that faucet flow, you might want to think again. What’s good enough for drinking isn’t always good enough for your brew.

Why Tap Water Doesn’t Cut It for Coffee

Tap water is often safe to drink, especially in many U.S. states with robust filtration systems. But "safe" doesn’t necessarily mean it’s good for coffee. The problem lies in what’s lurking in that tap water. Chlorine, for starters, is often added to municipal water supplies to kill bacteria, but its strong taste can overpower the delicate flavors of your coffee beans. Minerals like calcium and magnesium, while harmless, can throw off the balance, creating a brew that tastes flat, chalky, or metallic. And don’t even get me started on hard water—it’s a surefire way to turn your coffee into a bitter disappointment.

Even if your tap water tastes fine on its own, it can clash with coffee's flavor compounds during brewing. Coffee’s nuanced notes—those floral, fruity, or chocolatey hints—rely on the right chemical reactions. If your water isn’t chemically balanced, those flavors never shine. You’re left with a cup that’s either bland or too sharp, and no amount of creamer or sugar can rescue it.

When Tap Water Might Be Okay (Focus on The Might)

There are exceptions, of course. If you’re lucky enough to live in a region with soft water—low in minerals and free of chlorine—you might get away with using tap water for brewing. Think of places like Portland, Oregon, or Seattle, Washington, where the tap water is famously high-quality. But even then, it’s not a guarantee. Seasonal changes, aging pipes, or citywide maintenance can alter the water’s flavor and composition, leaving your coffee tasting like something brewed in a science experiment gone wrong.

For those in a pinch, using filtered tap water is a better compromise. A good water filter can remove most chlorine and reduce mineral content, making it less likely to clash with your coffee beans. Still, filtered water is only a halfway solution—it’s better than straight tap, but it won’t elevate your brew to barista-level perfection.

The Right Water for Coffee

If you’re serious about coffee, the best water for brewing is purified water with just the right balance of minerals. Distilled water, while tempting for its purity, isn’t ideal—it lacks the minerals needed to extract coffee’s full flavor. Too soft, and the brew tastes lifeless; too hard, and you risk bitterness. The sweet spot is water with around 150 parts per million (ppm) of total dissolved solids, which is just enough mineral content to complement, not overshadow, your coffee.

Some bottled waters meet this criterion, but not all are created equal. Brands marketed as “mineral water” often have high mineral levels, which can overpower coffee just like hard tap water. Spring water or purified water labeled for brewing tends to work best. For the true coffee connoisseur, investing in a home water filtration system or using coffee-specific water tablets to “build” the perfect water might be worth it.