Why The Water In Your Toilet Is Brown (And How To Fix It)

Finding brown water in your toilet can stir up many emotions, none of them good. Things get even worse when you can't figure out the cause and your mind starts running through a myriad of scenarios, each stranger than the last. But don't fret — brown water in the toilet is fairly common. Frequent causes include rusty pipes or parts, natural minerals, maintenance work, iron bacteria, and clogs.

Let's start with the rusty pipes. Per Consumer Notice, about 76 million American homes still have cast iron models, which were very cheap in the 1900s. But they come with a major flaw — they are susceptible to rust. When water runs through them, the cast iron can corrode, forming a coating that can color your water brown. But if you only notice this distressing hue in one toilet, it might be rusted toilet parts. If any of the many metal pieces in the fixture get rusty, they can release the iron oxide into the water. 

Sometimes your plumbing might not even be the issue — natural minerals can also cause brown toilet water. Iron and manganese naturally occur in aqua and can be deposited in your toilet tank when water usage is low. When you use the fixture, these minerals are stirred, causing brown-looking liquid. This is one of the many toilet problems caused by hard water.

Brown toilet water can also surface during or after maintenance work by your municipal water provider. These jobs might change water pressure, which can stir up the sediment in the pipes and cause your liquid to look brown. However, the color typically clears out after a few hours. If the brown water in your toilet looks slimy or has an oily sheen, then you might have iron bacteria in your pipes. These bacteria naturally occur in shallow ground waters and thrive in liquid with high iron content, as they live off the mineral. They're not visible to the naked eye, but they leave behind brown, slimy water that smells of rotten eggs or spoiled vegetables.

Clogged pipes can also cause the water in your toilet to turn brown. These blockages push wastewater back up the pipeline and into your toilet bowl, discoloring the liquid. They can be caused by foreign objects or even those "flushable" wipes that really aren't safe to flush. If your problem is caused by sewer line blockages, you'll likely know because it's usually accompanied by unpleasant odors.

The solution to your brown water problem depends on the cause. If your house was built in the 20th century, specifically before 1975, then you probably have cast iron pipes, and they might be rusted. In this case, open a few cold water faucets around your home to let out the excess coating. However, that doesn't solve your problem. The costlier but more efficient solution is to replace your entire plumbing system with new piping to eliminate the source of the rust. If the root of your issue is rusty toilet parts, then those have to go, and you might have to change your whole fixture (just be aware of things like flushing options and seat height before buying a new one for your bathroom).

If you suspect mineral buildup, you'll need a test kit to confirm your hypothesis. Pick from any of the best water testing kits on the market and get started. If you're proven right, use a water softener to remove excess minerals that cause hardness, which will prevent discoloration. In the case of iron bacteria, shock chlorination is a good bet as the chemical element kills the bacteria (add about 200 ppm to the water). 

At the end of the day, though, it's best to let a professional handle these issues, especially clogged pipes. Whether the brown water is in a single toilet or house-wide (which might indicate a sewer line blockage), your plumber can properly address the issue and prevent more problems in the future.