Kitchen Sink Water Turns Brown After Ice Maker Runs

Quick Answer:

If brown water appears at the kitchen sink right after the refrigerator’s ice maker cycles, it usually points to sediment or rust being drawn into the shared cold-water line, a clogged refrigerator filter, or a supply/venting issue at the sink. Start by isolating the refrigerator supply, checking the fridge filter and faucet aerator, and watching for drainage or venting symptoms before calling a pro.

Why This Happens

Sediment or rust in the cold-water line can be stirred and pushed toward fixtures when the ice maker draws water. Older copper or galvanized pipes, or long unused sections of line, are more likely to shed particles.
A clogged or aging refrigerator water filter can trap debris and then release a discolored flush when the ice maker runs.
Pressure changes while the ice maker fills can create brief backflow or suction effects if check valves or shutoffs are faulty, pulling water with sediment from nearby openings.
Venting or drainage problems under the sink (gurgling, slow drain, bad air-admittance valves) can make it look like the sink is contaminated after appliance cycles. That’s why it’s important to check both the appliance and the fixture.
If the problem is limited to hot water, the water heater or hot-water plumbing is more likely the source; if it’s cold-only and tied to the fridge timing, focus on the fridge supply and shared cold-water plumbing.

Step-by-Step What to Do

1. Observe and document

Note exactly when the discoloration occurs (immediately after ice maker fills, intermittently, only after long idle periods).
Record color (light brown, dark brown), any odor, and whether it affects hot, cold, or both taps.

2. Isolate the refrigerator

Locate and turn off the refrigerator water shutoff valve (usually behind the fridge or under the sink). Run the sink and watch whether brown water still appears when the ice maker is prevented from filling.
Run the fridge dispenser and a few ice cycles (with the valve open) to see whether the fridge itself produces discolored water or ice.

3. Check and replace the fridge water filter

If the fridge dispenser or ice looks or tastes off, replace the filter and flush several liters through the dispenser per the appliance instructions.

4. Inspect the sink fixture and supply components

Remove the faucet aerator and look for rust or debris; run the tap without the aerator to see if discoloration clears.
Inspect flexible supply lines, the shutoff valve, and any visible pipe fittings for corrosion or leaks. Replace noticeably corroded or old flexible lines.

5. Watch for venting or drain signs

Listen for gurgling or bubbling in the sink when the ice maker runs; check the cabinet under the sink for an air-admittance valve (AAV) and whether it’s working properly.
If drains are slow or there’s a foul smell, address the drain/vent issue separately — a drain problem can sometimes coincide with appliance cycling and cause confusing symptoms.

6. Run targeted diagnostics

With the fridge shutoff closed, run cold water at the sink and collect a sample. Then open the fridge water and run both the fridge and sink to compare samples. If only the fridge water is brown, the fridge supply or filter is the likely culprit.
If brown water shows at multiple cold fixtures when the ice maker runs, the issue may be in the shared supply line or the municipal connection; consult the utility if widespread.

7. Flush and retest

After replacing filters or clearing lines, flush the cold taps for several minutes. If the problem recurs only after an ice-maker cycle, repeat isolation tests and keep notes for a technician.
For related fixture issues, consult related guidance like Kitchen Sink Takes Over a Minute to Get Hot Water or check for build-up issues such as described in Kitchen Sink Has Slippery Black Film Around Drain to decide whether further cleaning or replacement is needed.

What Not to Do

Do not force fittings or tighten connections by brute force — that can break valves or strip threads.
Avoid using caustic drain chemicals to “clear” the problem — they won’t remove rust or sediment from supply lines and can damage pipes, seals, and fixtures.
Don’t ignore early warning signs like recurring discoloration, odd odors, or gurgling drains. Small issues that are left alone often become larger and costlier to fix.
Don’t drink or cook with clearly discolored water until you’ve identified the source and flushed or fixed it.

When to Call a Professional

Call a plumber or appliance technician if you can’t isolate the source (fridge vs. sink) or if discoloration returns after basic flushing and filter replacement.
Get professional help if you find visible corrosion on supply lines, a leaking valve, or if multiple fixtures are affected — these can be signs of failing plumbing that require repair or replacement.
If municipal water discoloration affects your whole house, contact your water provider and then a plumber if repairs to your service line or shutoff are needed.

Safety Notes

Don’t drink or prepare food with discolored water. Use bottled or boiled water for consumption until the issue is resolved.
When working under the sink, turn off the cold-water shutoff valve before disconnecting supply lines to avoid flooding.
Avoid electrical contact with standing water. If a leak has reached electrical outlets or appliances, shut off power to that area and call a professional.

Common Homeowner Questions

Why is the water brown only sometimes? Short bursts of brown water often come from loose sediment that’s stirred when an appliance draws water; it may settle again until disturbed.
Will flushing the lines permanently fix it? Flushing helps remove loose debris, but if the source is corroded pipe or a failing valve/filter, the problem may return until that component is replaced.
Can I do any repairs myself? You can safely replace a fridge water filter, remove and clean an aerator, and turn off the fridge supply to test. Leave valve replacement, pipe work, or hidden leaks to a licensed plumber if you’re unsure.