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How to fix yellow tap water
Avoid using the tap water until you determine a cause.
Although water discoloration can be harmless, your safest option is to stop drinking it until you know what turned it yellow. Until you're certain what the cause is, drink bottled water and avoid cooking or washing with the tap water.
Turn on your sink for several minutes to see if the water turns clear. If the water clears out after several minutes, the issue is likely with your house plumbing.