An off-flavor that isn't explained by your beans usually comes from the water itself, or from something the water is picking up on its way through the machine. Here's how to narrow it down.
01New machine, plastic or "factory" taste
Brand-new machines often carry a faint plastic or manufacturing residue taste for the first several uses. Run 3-4 full cycles of plain water through the machine (no coffee) before judging the taste of your first real shot.
02Old or stagnant water in the tank
Water left sitting in the tank for days develops a flat, sometimes metallic taste, especially in machines without a lid seal. Empty and refill the tank with fresh water daily if you don't use the machine every day.
03Expired or missing water filter
Machines with a built-in water filter (common in super-automatic machines) need that filter replaced on a schedule — typically every 2-3 months with regular use. An expired filter can add a distinctly off or carbon-like taste rather than removing impurities.
04Mineral buildup in internal tubing
Scale doesn't just affect pressure and flow — it can also affect taste, giving shots a slightly metallic or chalky edge. If you're also seeing slower flow or weaker steam, descaling is likely to fix both issues at once.
05Very hard tap water
If the taste issue started with a house move or a change in your water supply rather than with the machine itself, your local water hardness or mineral content may simply be high. A basic water filter pitcher before filling the tank often resolves this without any machine work at all.
| Symptom | Most likely cause |
|---|---|
| Only in the first few uses of a new machine | Factory residue — flush with plain water |
| Flat or stale taste | Old water sitting in the tank |
| Metallic or chalky taste, gradually appearing | Expired filter or scale buildup |