By Sarah · Updated May 2026
Disclosure: As an Amazon Associate, Grind Those Beans earns from qualifying purchases. We only recommend products we believe in.
Water makes up about 98% of your coffee. You can dial in your grind size, nail your brew temperature, and still end up with flat, metallic coffee if your water’s off. Most of us fill the reservoir straight from the tap without thinking twice, but what’s dissolved in that water — calcium, magnesium, chlorine, minerals — shapes extraction, flavor clarity, and how often you’ll be descaling.
The right water brings out sweetness and complexity. The wrong water leaves scale buildup in your boiler, mutes acidity, or strips away body entirely. If you’ve been chasing a clean cup with a long, sweet finish and can’t seem to get there, your water might be the missing piece. Let’s figure out what belongs in your machine.
What you’ll need
- Your coffee machine (drip, espresso, pour-over brewer)
- Water testing strips or TDS meter (optional but helpful)
- Filtered water pitcher or inline filter
- Bottled spring water (for comparison)
- Distilled or reverse-osmosis water (for blending only)
- Remineralization packets like Third Wave Water (optional)
Step 1: Test your tap water’s mineral content
Grab a TDS meter or water hardness test strips from a home store or online. You’re looking for total dissolved solids between 75–250 ppm for coffee, ideally around 150 ppm. If your tap reads above 250, expect faster scale buildup and a heavier, sometimes chalky cup.
Step 2: Avoid distilled or reverse-osmosis water alone
Distilled and RO water have nearly zero minerals — they’re too “soft” and will underextract your coffee, leaving it sour and thin. In espresso machines, soft water can also corrode metal components over time because it’s slightly aggressive. If you only have access to distilled, you’ll need to remineralize it.
Step 3: Use filtered tap water for most setups
A simple carbon filter pitcher (Brita, PUR) removes chlorine and off-flavors while leaving helpful minerals like calcium and magnesium intact. This is the sweet spot for drip machines and pour-over: clean flavor, adequate extraction, and moderate scale prevention. Change your filter every two months.
Step 4: Try bottled spring water as a benchmark
Grab a jug of spring water with a mineral content label — look for calcium around 20–80 mg/L and magnesium around 10–30 mg/L. Brew a pot with it, then compare side by side with your usual water. You’ll taste the difference immediately: better clarity, balanced sweetness, no chemical twang.
Step 5: Consider remineralization for espresso machines
If you’re serious about espresso and have very soft or very hard tap water, use a remineralization product like Third Wave Water or Lotus Water. You add a packet to distilled or RO water to hit the ideal TDS and mineral balance. Yes, it’s an extra step — but it protects your machine and unlocks cleaner shots.
Step 6: Check your local water hardness map
Search “water hardness map [your city]” or check your municipal water report online. If you live in the Southwest, Midwest, or parts of Florida, you likely have hard water (high calcium). Coastal and Pacific Northwest areas tend to be softer. Knowing your baseline helps you decide if filtration or remineralization is worth it.
Step 7: Adjust your descaling schedule accordingly
Hard water means more frequent descaling — every 1–2 months for espresso machines, every 3 months for drip. Filtered or spring water can stretch that to 3–6 months. Keep a calendar reminder and stick to it; scale buildup kills heating elements and ruins flow rate long before you see white flakes.
Pro tips & common mistakes
A common mistake is assuming bottled \”drinking water\” is the same as spring water — many brands are just filtered tap with no mineral label, so read the back. If you’re blending your own water, start with 1 part tap to 2 parts distilled and adjust from there based on taste. For pour-over and drip, you have more wiggle room; espresso machines are far less forgiving and benefit most from stable, moderate hardness.
If your machine has started sputtering, taking longer to heat, or producing weak shots even with fresh beans, scale is likely the culprit — not your grinder or technique. Don’t wait for a full breakdown. Most manufacturers will void your warranty if you’ve used distilled water exclusively, so check your manual. When in doubt, filtered tap is your safest, most practical choice.
Related guides
- Steamed Milk or Frothed: How to Choose for Your Coffee
- Review: V60 Coffee Machine Hario (Pour Over Coffee Starter Set)
- Why Does My Coffee Taste Bad From My Machine?
- How to Descale a Breville Espresso Machine
Frequently asked questions
Why is distilled water bad for espresso machines?
Distilled water has no minerals, which makes it slightly acidic and can corrode brass, copper, and aluminum parts in your boiler over time. It also underextracts coffee, giving you sour, hollow shots. Most espresso machine warranties explicitly prohibit distilled-only use.
What’s the ideal TDS for coffee brewing?
The Specialty Coffee Association recommends 75–250 ppm total dissolved solids, with a sweet spot around 150 ppm. This range provides enough calcium and magnesium for proper extraction without excessive scale buildup. You can measure TDS with an inexpensive handheld meter.
Can I use bottled water in my coffee maker every day?
Absolutely. Bottled spring water is a great option if your tap water tastes off or is extremely hard. Just check the label for mineral content — you want some calcium and magnesium, not zero. It’s more expensive than filtering tap, but convenient and consistent.
How often should I descale if I use filtered water?
With filtered tap water, plan to descale your espresso machine every 3–6 months and your drip machine every 4–6 months. If you notice slower brewing, weaker coffee, or unusual noises, descale sooner. Hard tap water cuts that interval in half.
What are remineralization packets and do I need them?
Products like Third Wave Water add precise amounts of calcium, magnesium, and other minerals to distilled or RO water, creating ideal brewing water. They’re popular with serious espresso enthusiasts and competition baristas, but overkill for most home drip brewers. Filtered tap usually does the job.
Is soft water better than hard water for coffee?
Not necessarily. Moderately hard water (50–150 ppm) extracts coffee well and adds body. Very soft water can underextract and taste flat, while very hard water overextracts, scales up your machine, and can taste chalky. You want the middle ground.