A taste that has always been there and a taste that appeared last week are different problems. The second one is more tractable, because something changed and the change can usually be located with a few minutes of testing rather than by buying a filter and hoping. Start by narrowing down where the taste is coming from.
Narrow it down first
Four quick checks. Does it affect every tap or one? One tap means the fixture or the pipework serving it. Does it affect hot only? That points at the water heater rather than the supply. Does the first draw taste different from water run for a minute? That means the plumbing is contributing while water stands. And does bottled water taste normal to you? If it does not, the change is in your own taste perception rather than in the water at all.
The supply side possibilities
Utilities switch sources and blend differently through the year, which changes mineral content and therefore taste, and some carry out a temporary switch from chloramine to free chlorine for maintenance, which tastes markedly stronger. Main works stir sediment and can produce an earthy or metallic taste for days. The EPA requires every community water system to publish an annual Consumer Confidence Report and maintains a finder for them, and the utility can confirm any recent change if you ask.
Your own plumbing and appliances
New copper pipework, fresh solder joints and new plastic pipe all impart taste for weeks after installation. A water heater whose anode is reacting with sulfate gives a rotten egg smell on the hot side only. A filter cartridge left in long past its life stops working and can begin releasing what it captured, which is a genuinely common cause of a taste appearing suddenly in a household that has a filter and forgot about it. Check the cartridge date before anything else.
When to escalate
A taste alongside discolored water, a boil notice or an advisory goes to the utility, not into a filter. A metallic taste with blue green staining means acidic water dissolving copper from your own pipework, and that is progressive and worth attending to promptly. A fuel or solvent taste is a reason to stop drinking the water and get it tested, particularly on a well near fuel storage or a road. Our softener guide covers the mineral tastes that are simply preference.
Questions people ask about why does my water taste weird
How do I work out where the taste comes from?
Check whether it affects every tap or one, hot only, the first draw only, and whether bottled water tastes normal to you.
Why would the taste change suddenly?
Seasonal source switching by the utility, main works stirring sediment, new pipework curing, or a filter cartridge long past its life.
Rotten egg smell on hot water only?
The heater's anode reacting with sulfate in the water. That is an appliance matter rather than a supply treatment one.
When should I stop drinking it?
A fuel or solvent taste, or any taste alongside discoloration or an advisory. Those need testing and the utility, not a filter.