Why Is My Tap Water Brown or Rusty? Causes and Next Steps
Brown water is alarming but usually has a simple cause. A two minute test tells you whether it comes from your house or the street.
- 24/7 emergency calls
- Nights, weekends and holidays
- Mission Viejo, CA
What Brown Water Usually Is
Rust colored water usually means iron or other minerals are loose in the pipes. The U.S. EPA lists iron in its secondary standards at 0.3 milligrams per liter. At that level it says people may notice a rusty color, sediment, a metallic taste and reddish or orange staining.
EPA also lists manganese at 0.05 milligrams per liter, with black to brown color and black staining. These secondary standards address looks, taste and staining. They are not the same as health limits.
If your water has changed color, do not guess. A few simple tests tell you where the problem begins, and they cost nothing. This guide explains the tests and what each result suggests.
The Two Minute Test
The City of Portland's water bureau gives a clear method for sorting causes. Its three main sources are home plumbing, water system maintenance and system activity such as hydrant use. The test below follows the same logic, and it works in any city.
Compare hot and cold
Run each tap separately. If only the hot water is discolored, the water heater or hot pipes are the likely source.
Try several faucets
Test a tap on each floor and one outside. Discoloration at only some taps points to your own plumbing. Discoloration at all of them points to the street.
Run the cold water
Run a cold tap for one to two minutes. If it clears fast, the issue may be in your pipes. If not, a neighborhood event may be under way.
Report it
If the water stays discolored, call your water district. In Mission Viejo that is one of three districts, so check your bill.
Avoid running the washer while the water is brown. Dark water can stain laundry, and clearing the line first protects your clothes.
Common Causes and What They Look Like
| Pattern | Likely cause | Next step |
|---|---|---|
| Only hot water is brown | Sediment or corrosion in the water heater | Flush the tank and have it inspected |
| Brown at every tap, clears in minutes | Work or a hydrant event on the street | Run cold water until clear and call your district if it lingers |
| Brown after a long absence | Water sat in old pipes | Flush the lines for a few minutes |
| One tap only | Corroded fixture or local pipe | Have that run of pipe checked |
| Constant rust stains and flaking | Aging galvanized or iron pipe | Ask a plumber about a repipe |
These patterns are a starting point. A plumber can confirm the cause by looking at the pipe material and the water heater.
When It Points to Your Water Heater
Hot water that is brown while the cold water runs clear is a strong hint. Rust inside a steel tank can flake loose and tint the water. A flush may clear the sediment, as the yearly steps in our water heater maintenance checklist explain.
If the tank is old and the water keeps coming out rusty after a flush, the lining may be failing. That is the point where replacing the heater makes more sense than another flush. Do not wait for a leak to confirm it.
What Not to Do
- Do not drink or cook with water that is visibly brown.
- Do not run the washer or dishwasher until the water clears.
- Do not assume a filter pitcher will fix a color problem at the source.
- Do not ignore brown water that returns every few days.
- Do not drain the water heater without turning off its power or gas first.
Most one time brown events clear in minutes. A pattern is different and deserves a look.
What to Tell Your Water District or a Plumber
Details speed up the diagnosis. Say which taps are affected, whether hot, cold or both, and what time it happens. Note any street work, hydrant use or long absences before it started.
If you can, fill a clear glass and take a photo. A picture of the water and a note of the date help a district or a plumber. Keep the record if the problem returns.
A Note for Older Homes in Mission Viejo
Mission Viejo grew from the 1960s onward, so many homes are decades old. Pipe materials in older houses vary, and not every house has been repiped. Rust stains, low pressure and discolored water together are worth a plumber's look.
A plumber can check an exposed pipe in the garage or a crawl space. A pipe's color and surface often show the material. Ask about the material at your next visit and keep a note of it.
When It Points to Old Pipes
Water that is brown at every tap, comes back day after day and leaves rust stains on fixtures may mean the pipes are corroding from the inside. Older homes sometimes have galvanized steel supply lines, which are known to rust over decades. A plumber can check the pipe material and look at the condition of the lines.
If the lines are failing, a repipe replaces them with new pipe and ends the cycle of patching. Read whole house repiping to see how that work is done. Until then, avoid drinking or cooking with water that is visibly discolored.
Water coming out brown and not clearing?
Call and tell us which taps are affected and whether hot or cold. The plumber can tell you what to check first.
Sources and Standards
Local figures and standards on this page come from these published sources.
Common Questions
The EPA treats iron and manganese limits as secondary standards for color, taste and staining. Still, avoid drinking visibly discolored water and call your district if it persists.
That usually points to the water heater, either sediment or rust inside the tank.
Work or hydrant use can stir sediment in the main. Running cold water for a few minutes often clears it.
No. Wait until the water runs clear so it does not stain the laundry.
Not always. A flush or a heater repair may be enough. Persistent rust at every tap in an older home can point to failing pipes.
Brown Water Not Clearing Up?
Call any hour in Mission Viejo. Tell the plumber which taps are affected and what the water looks like.
Call (949) 998-2846