What are the red streaks in my toilet occasionally? It seems to come from where the water flows when flushing and go around the bowl. Sometimes settling in the bottom where the little bit of water lies.

  • Do you ever notice it from other taps or other toilets, or when you fill up the bathtub, or is it isolated to one toilet? – Joel Spolsky Aug 18 '10 at 15:09
  • @Joel: I only have one toilet. I don't see it out of the faucet in the kitchen, sinks, or bathtub. – Brian Aug 18 '10 at 15:11
  • Where do you get your water from? Where do you live? (If you have a well and your filter is not working right, it might be clay or sand) – Joel Spolsky Aug 18 '10 at 15:35
  • @Joel: City. In Florida, east coast – Brian Aug 18 '10 at 17:37
  • A picture would really help. – Kris K. Aug 2 '11 at 14:30

This article suggests it might be a bacteria known as Serratia marcescen

if you’ve noticed a pink or red slimy substance forming in your toilet bowl, you’re not alone.

It is bacteria known as Serratia marcescens, according to Roxanne Johnson, North Dakota State University Extension Service water quality associate.

You may find this bacterium in moist areas such as toilet bowls, sinks, tiles, shower stalls, bathtub enclosures and even your pet’s water dish. The bacteria will grow in places with materials containing phosphorus or fatty substances such as feces residues in your toilet or soap residue in a pet’s dish or the bathtub, shower and sink.

Occasionally the pinkish film appears during and after new construction or remodeling activities. You see it more commonly when you have your windows open during the summer months.

“I have observed this phenomenon form in the toilet bowl along the water line and at the openings where the water enters the toilet bowl, usually when I’m gone for a few days, or in my guest bathroom that isn’t used often,” Johnson says.

“The bacteria survive there because the water sits for a period of time, with the chlorine dissipating as it stands,” she adds. “If you have an activated carbon filter on your water line, you are removing the chlorine and may be supporting the growth of the bacteria.”

While the genus Serratia is not known to be a water-borne disease, it has been known to be pathogenic to some people, causing pneumonia, wound infections and urinary tract infections in some hospital settings.

The bacteria are difficult to remove completely from your home, although the stains are removed easily with a general-purpose cleanser containing chlorine bleach. You also may add ¼ cup of bleach to the toilet tank, let it sit for 15 to 20 minutes and then flush the tank a few times to remove all of the bleach. Do not leave bleach sitting in your tank because it will damage rubber valves and seals.

Johnson recommends you scrub with a brush and household cleaner to clean pet bowls, kitchen surfaces and bathroom sinks, bathtubs and showers. Follow this up with a strong chlorine bleach solution, leaving the bleach in contact with the surfaces for 10 to 20 minutes to disinfect the area. Then rinse well with water.

To prevent the bacteria from developing, wipe down and dry all sinks and bathtubs after using them, and use a cleaning solution that contains bleach.

  • 5
    It can help if you quote a bit from the article linked to. First so all the information is on one page, second so people can decide whether they want to click the link or not, and third to guard against link rot. – ChrisF Aug 18 '10 at 14:49
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    Be careful not to mix chlorine bleach with acid, found in some toilet bowl cleansers. This mixture produces poisonous chlorine gas. – Bill Karwin Sep 16 '10 at 4:22

Possibly rust.

Is it just the toilet or do you get it from any of the other taps in the house?

If it's just the toilet then look in the cistern to see if there's anything rusting in there. If it's not a close coupled toilet check the pipe between the cistern and the bowl.

If there's red from any of the other taps in the house then the problem is with the supply.


The other thing you can try is to put some bleach if your tank. It will kill any of the organics, which is potentially the cause of the red staining. The bleach also makes the bathroom smell nice, in my opinion. I do this about once every two months... 4 kids introduce lots of organics into a toilet :).


I use white vinegar to clean the toilets and it gets rid of the red streaks. After flushing I then put about 2 cap fulls of white vinegar into the tank and from one week to the next the streaks were thinner and took a little longer to appear. P.S. This method takes very little White Vinegar to use and is cheaper. It's also non toxic and effective.

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