Turning on the tap and getting brown or rust-colored water instead of clear is one of those moments that tends to produce immediate concern. The instinct to worry is reasonable. Water that looks like that doesn’t look safe, and the first question most people have is if it is.
The answer depends on where the discoloration is coming from, and that’s worth figuring out before assuming the worst or doing nothing. Brown water from a tap in a Florida home can have several causes, some of which resolve on their own within minutes, and some of which point to a problem that needs a plumber’s attention.
What the Color Is Telling You
The brown or rusty color in tap water almost always comes from iron or manganese. These minerals can enter the water supply from corroding pipes inside the home, from sediment disturbance in the water main, or from changes in municipal water pressure or flow direction that stir up deposits in the distribution system.
The source of the discoloration determines what to do about it. Discoloration that comes from outside the home, meaning from the municipal supply, usually clears on its own. Discoloration that originates inside the home’s plumbing doesn’t go away by running the water and requires investigation.
The First Thing to Do: Cold Water Test
In the first ten minutes, the most useful thing to do is run only cold water from several different taps around the house. The cold water supply and the hot water supply are separate systems up to the point where they meet at fixtures, so testing cold water only isolates the supply lines from the water heater.
If the cold water runs clear at every tap after a minute or two of flushing, the discoloration is likely coming from the water heater. If the cold water is brown at every tap, the source is probably outside the home or in the main supply line. If cold water is brown at some taps but clear at others, there may be a problem in a specific section of the interior supply lines.
Testing Hot Water Separately
Once the cold water test is done, run only hot water at a fixture. If the hot water is brown and the cold is clear, sediment in the water heater is the most likely cause. Water heaters accumulate mineral sediment at the bottom of the tank over time. When the heater is disturbed by pressure changes or a heating cycle, that sediment can circulate into the hot water supply.
A water heater that’s producing discolored hot water may need to be flushed, or if the sediment has been building for years, the unit may be approaching the end of its service life.
When the Problem Is Outside the Home
Municipal water main disturbances are a common cause of temporary tap water discoloration in South Florida. Nearby construction, a water main break, a fire hydrant being opened, or a change in flow direction in the distribution system can all stir up mineral deposits inside the main and push discolored water into homes in the area.
In these situations, the water utility is the first call. Most South Florida utilities have a customer service line where you can report the issue and find out if there’s a known main disturbance in the area. If there is, the recommendation is usually to run cold water from an outdoor tap or a tap at the front of the house for several minutes to flush the affected water through.
During a known main disturbance, avoid running the washing machine or dishwasher until the water clears. The discolored water can stain laundry and leave deposits in appliances.
When the Problem Is Inside the Home
If the water utility has no reported issue and the cold water is brown coming out of multiple interior taps, the discoloration is likely originating from the home’s own supply lines.
Galvanized Steel Pipe Corrosion
Homes built before the mid-1970s in South Florida often have galvanized steel supply lines. Galvanized pipe corrodes from the inside out as the zinc coating deteriorates over decades. Once the zinc is gone, the steel beneath it oxidizes and produces iron oxide, which is what gives the water its brown or rust color.
Galvanized pipe that’s producing discolored water is corroding actively. The discoloration tends to be worst first thing in the morning after water has been sitting in the pipe overnight, and it may improve after several minutes of flushing. But the underlying corrosion doesn’t stop, and the pipe will eventually fail. Persistent brown water from galvanized pipes is a reliable indicator that the supply lines need to be replaced.
Copper Pipe Corrosion
Copper pipes in South Florida can develop corrosion issues related to the water chemistry in certain municipal supply areas. When copper corrodes, it can release copper into the water, which produces a blue-green tint rather than a brown one. However, when copper pipes have developed scale buildup internally or have areas of corrosion near fittings, particulate matter can discolor the water.
When to Call a Plumber
If cold water is running brown and the utility has no reported issue, or if the water clears temporarily but comes back brown consistently, or if the discoloration is accompanied by reduced pressure or sediment particles in the water, those are the situations that warrant a call to a licensed plumber.
A plumber can assess the condition of the supply lines, test water pressure, and determine where the discoloration is originating. In many South Florida homes, the discovery of brown water leads to finding galvanized pipe that’s been corroding for years and is overdue for replacement. Catching that before the pipe fails completely is the better outcome.
