In most cases, brown tap water is not an emergency. It is, however, a signal worth understanding. Start with the three immediate steps below, then identify your specific cause.
Until you identify the cause, use bottled water for drinking, formula prep, and cooking. Showering is generally fine.
Text a neighbor. If multiple units have brown water, it’s likely a city main event. If only your unit, it’s building-specific.
After confirming no active city event, flush cold water. If color clears completely, the disturbance has passed.
CAUSE DIAGNOSIS
When the water department opens a fire hydrant for flushing or emergency work, the velocity surge dislodges iron and manganese sediment that has accumulated at the bottom of distribution mains over decades. This sediment flows through connected service lines into buildings. The discoloration is temporary and clears as normal flow velocity returns after the event. Check NYC311 or the DEP website to confirm any active work in your area.
Action: Run cold water periodically. Clears within 1–3 hours after the city event ends. No health concern at these concentrations.
Most likely to have original galvanized risers and pre-1986 lead solder. First-draw morning discoloration common. Brown water may recur consistently.
Mix of plumbing ages. Some galvanized, some early copper. Roof tank sediment can cause occasional events. Less consistent than older walk-ups.
Modern copper or PEX plumbing. Brown water almost always comes from the city main, not the building. Clears quickly once the external event resolves.
Scratches to reveal shiny metal underneath. Attracts a magnet. Common in pre-1960 buildings. Corrodes internally — the outside looks fine while the inside rusts progressively.
Does not attract a magnet. Makes a clear ring sound when tapped with a key. If pre-1986, may have lead-tin solder at joints. The pipe itself is not the risk — the joints are.
Very soft — scratches easily to a shiny surface. Does not ring when tapped. Does not attract a magnet. Primarily found as service lines in pre-1950 buildings, not typically as interior supply pipes.
Flexible (PEX) or rigid white/cream (CPVC). No metal solder. Modern alternative standard since the 1990s. If your building was re-piped with PEX, lead solder is not a concern at those runs.
Brown water that does not clear after 20+ minutes of running. Brown water accompanied by low pressure or pressure fluctuations. Water with a sewage or chemical odor (unrelated to iron/rust smell). Any oily sheen on the water surface. Water that becomes darker rather than lighter as you run the tap.
Building super: Unit-specific or building-wide. Report in writing (text/email) for documentation. NYC 311 / nyc.gov: Check for reported main work in your area before calling. NYC DEP (718-DEP-HELP): If 311 shows no reported work and the problem is building-wide and persistent. Board of Health: If building management is unresponsive to documented recurring issues affecting health.
PIPE MATERIAL GUIDE
Corrodes internally while exterior looks intact. Common pre-1960. First-draw morning discoloration is a consistent pattern, not a one-time event.
Pipe itself won't cause brown water. If pre-1986: lead-tin solder at joints is the separate concern.
Primarily found as the service line in pre-1950 buildings. Doesn't cause brown water — but pressure events that disturb iron sediment can also disturb lead particles.
Post-1990 new construction or re-pipe. No iron corrosion, no lead solder. Discoloration almost always traces to an external main event.
⚠Brown water doesn’t clear after 20+ minutes of running
⚠Discoloration has a sewage, sulfur, or chemical smell — not normal metallic/earthy iron odor
⚠Any oily sheen appears on the water surface
⚠Water gets darker, not lighter, as you run the tap