Why does my tap water taste bad?

A swimming-pool smell is the disinfectant residual, which water systems are required to maintain throughout the distribution network. Free chlorine is the more noticeable of the two; chloramine, used by many systems for a more stable residual, tends to read as a duller chemical or slightly medicinal taste rather than a sharp one.

Residual concentration varies with your distance from the treatment plant and with the season, so a taste that comes and goes over the year is normal rather than a fault. Activated carbon removes free chlorine easily; chloramine needs catalytic carbon and adequate contact time, which is why a cheap pitcher filter sometimes disappoints on a chloraminated supply. Refrigerating water in an open jug for a few hours reduces free chlorine noticeably and does very little for chloramine.

Each New Jersey system reports its residual and disinfection byproduct figures annually, and those figures sit on the system pages on this site.

Hydrogen sulfide produces the classic rotten-egg odour. On a private well it usually comes from the groundwater itself or from sulfate-reducing bacteria in the well or plumbing. On a municipal supply it is uncommon in the water arriving at the house.

The most frequent cause of a sulfur smell at a single fixture is the water heater: the magnesium anode rod reacts with sulfate-reducing bacteria in the tank. The tell is that the smell appears on hot water only. Replacing the anode with an aluminium or powered version, and sanitising the tank, addresses it. If both hot and cold smell, at every tap, the source is upstream and oxidising filtration or aeration is the usual treatment.

A metallic taste generally means metal: iron and manganese from the source water, or copper and zinc picked up from your own pipes. Iron also stains laundry and fixtures and is measured on the reported panel; corrosion from your plumbing is not, because it happens after the meter.

A metallic taste that is strongest first thing in the morning, from water that has sat in the pipes overnight, is a plumbing-contact signature. That pattern is also the one associated with lead leaching in homes with lead service lines or lead solder, and lead has no taste at the levels that matter — which is why the EPA advises flushing the line after long stagnation and testing rather than judging by taste. Salty or brackish notes point to sodium and chloride, whether from road salt intrusion, a coastal aquifer or a softener discharging incorrectly.

Reservoir-sourced supplies get seasonal taste episodes from geosmin and 2-methylisoborneol, compounds produced by algae and actinobacteria. Human noses detect them at a few nanograms per litre — far below any health threshold — which is why a system can be fully compliant and still get a wave of complaints in late summer. These episodes pass, and activated carbon handles them in the meantime.

A musty smell confined to one sink, particularly with a slow drain, is often the drain rather than the water. Filling a glass and smelling it in another room is a crude but effective test.

Establish scope first: one tap or all, hot or cold, constant or intermittent, better after flushing or not. Then read the annual report for your system — if a taste complaint coincides with a documented change in disinfection or source, that is your answer without spending anything.

Where treatment is warranted, carbon is the default for taste and odour and is inexpensive. Reverse osmosis is the broader option and is discussed in reverse osmosis explained. Note that a softener does not improve taste and can make water taste slightly flat to some people; the distinction is set out in filtration vs softening. A sudden change in taste, colour or smell with no obvious cause is worth reporting to your utility, which is obliged to investigate.