Five Reasons Your Tap Water Changed Color

Americans are watching their tap water more closely than ever these days following the lead crisis in Flint, Mich., and other incidents of water contamination around the country.

It’s impossible for the human eye, nose or tongue to detect some changes in tap water. But others are hard to miss.

We reviewed public information provided by major American water utilities to identify the major causes of discolored drinking water. While the factors can vary across regions, seasons and water sources, water systems encounter many common issues.

If your tap water has turned brown, murky, cloudy or otherwise discolored, here are five likely reasons why – and what you should do about it: 

New Water Source

A new water source, such as a reservoir or river, is one of the most common causes of changes in water quality. In fact, experts say a change in source triggered both the current lead crisis in Flint and a similar debacle in Washington, D.C. in the early 2000s. The switch can give the water different qualities or disrupt the way it flows, both of which can affect the look, taste, odor or healthfulness of your water.

Organic Material

Dirt and other naturally occurring sediments settle at the bottom of water supply lines. If something causes the water passing through the pipes to speed up – such as a water main break, high service demand or even firefighting – the faster flow can stir up the sediment and cause your water to appear yellow or brown.

Pipe Material  

When cast iron and lead pipes corrode over time, rust and other pipe materials flake off into the water. Iron and manganese produce an orange-to-brown color, while lead may make the water darker and include tiny particles. Rubber plumbing materials, such as gaskets or O-rings, can break down into visible black particles in water. As with organic material, more pipe materials dislodge when water flows more quickly through service lines.  


Extra air trapped in or moving through water can give it a milky white or cloudy appearance.

Upstream pollution

Rainwater can wash chemicals – such as pesticides in agricultural communities, residue from fracking operations or motor oil on highways – into the surface water or groundwater that feeds your tap.

EWG's Guide to Safe Drinking Water

Reduce your exposures to common drinking water pollutants with EWG's handy tipsheet!

What you should do:

Discoloration doesn’t necessarily mean your water has become unhealthful. Many sources of tap water discoloration are listed in the Environmental Protection Agency’s  “secondary standards,” which recommend maximum levels for 15 contaminants that may affect color, odor or taste – but won’t hurt your health.

Still, you should always investigate changes in your water’s color, smell and taste, or if you notice stains on your clothes after washing.

If your water is milky or opaque, let it sit in a glass until bubbles rise. If the cloudiness disappears, it was caused by air and is not a health concern. If your water is discolored, run cold water from the tap to see if it clears. (It may take a while.) Check with your neighbors to see if they have similar problems.

Then visit your local utility’s website. Try the FAQ section or look for recent announcements. Utilities may issue notifications about upcoming work to a main line or potential changes to the water supply. They may even advise using boiled or bottled water.

Call for additional information. Ask your utility if it monitors for secondary contaminants – a step that the EPA does not require – and find out if your water meets the EPA’s “secondary maximum containment level” guidelines (SMCLs). Inquire about any short-term disturbances to your water supply that might be due to maintenance or other temporary issues. You can also call EPA’s Safe Drinking Water Hotline at (800) 426-4791 for assistance.

Once you’ve identified what’s causing the discoloration, choose an appropriate water filter. Check EWG’s Updated Water Filter Buying Guide to find one that’s right for your needs and budget, and choose a model that is certified to reduce the specific contaminants in your tap water.

If you cannot pinpoint a cause, we suggest using an activated carbon filter (pitcher-style or faucet-mounted). These tend to be inexpensive and effective at removing or reducing many common contaminants. They are also good at improving the clarity and taste of temporarily discolored water.

If you drink water from a well, contact a state-certified commercial laboratory to get it tested. EPA recommends testing for sulfate, chloride, iron, manganese, hardness and corrosion every three years or if your water changes in color, taste or smell. Bacterial contamination can discolor well water as well, so contact your county health department. Here’s more information about testing your water.

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