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Thread: Black deposits in low flow toilets

  1. #1

    Default Black deposits in low flow toilets

    This question was asked in July 2001 by another woman but got no responses. Now, I am having the identical problem. She wrote, "Has anyone else experienced a problem with nasty black deposits at the waterline in the bowl of a low flow toilet? Ever since my apartment bldg replaced our old toilets with the low flows, I've had these black deposits appearing almost daily. I thought they were mildew stains, but mildew removers like X-14 have no effect. They come off easily with scrubbing, but I've found no way to keep them from coming back. What causes them? What can I do to prevent them? " In my case, I recently purchased a new house and all three toilets develop these nasty black streaks. They wash off easily but are really disgusting. Is it the pipes, or is it the toilets?

  2. #2
    Retired Defense Industry Engineer jadnashua's Avatar
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    This is just a guess...do you use one of those cleaner tablets or other dispenser devices that sits in the tank? the black could be rubber deposits that are being eaten up by the excess chlorine from those devices.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  3. #3

    Default Reply to jadnashua

    I have never used a product that sits inside the tank. All I use is a pine-scented cleaner and brush. It is a mystery. The streaks that form in the tank come from the small holes underneath the rim. Sometimes the black substance forms a ring at the water line first, then it forms lines down from the holes to the water line. Other times, the streaks will "grow" from under the rim and ultimately reach the water in the bowl. Once the bowl is cleaned it takes approximately 2-3 days for it to start all over again. I have never, ever seen anything like this. I am beginning to regret purchasing this new house with low flow toilets.

  4. #4

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    Is the surface (i.e. the path between the rim holes and the waterline) etched or rough there maybe from mineral deposits? If so it could be allowing small amounts of moisture to stay on there (instead of running down into the water). This would be especially pronounced if you flush that toilet infrequently.

    I had a similar issue previously, however it was a type of mildew/mold and seemed to crop up a certain times of the year (not sure if because of the water or the environmental conditions). In my case, it seemed to accumlate where someone had apparently scratched the bowl serface with a rough brush.

    I ended up replacing the toilet and problem was solved.

    Here is one thing to try to verify it isn't mold/mildew, go ahead and use a "blue" cleaner/dispenser. I'd bet if it is mold, normal flushing will probably eliminate or at least retard.

  5. #5

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    I am willing to try almost any suggestion. The house is only four months old. All of the toilets are new. This problem has been occuring since the day I moved in.

  6. #6
    Retired Defense Industry Engineer jadnashua's Avatar
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    I don't think that you can attribute the stains to the toilets, or everyone would see the same thing. My guess is there is something in your water. If you take a glass and fill it with cold water from the tap then let is sit for several days - leave it for up to a week or so. See if you get similar things.

    Maybe someone else will have an idea. Did you say that others in your neighborhood have similar problems? Maybe you should take it up with the city or town water people .
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  7. #7

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    I have asked three other neighbors and none seem to have this problem (or they won't admit it.) In the last two days I have had a plumber, then his supervisor, come to the house to investigate. Neither one has seen anything like this before. The supervisor said to try a bleach-type tablet in the tank. His reasoning was that low flow toilets do not eliminate all of the water in the tank with each flush - and that might be promoting a mold/mildew buildup. The second plumber checked the inside of all three toilet tanks and he also went into the attic to see if the water heater had any type of residue in the pan. (To be honest I'm not sure really why he went into the attic or what he looked at...) Everything looked clean. I have decided that low flow toilets are not all that great and I would prefer to have traditional toilets in my home.

  8. #8
    Retired Defense Industry Engineer jadnashua's Avatar
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    None of the toilets exchange all of the water with each flush. They do flush all of the water out of the bowl, but there is always a little left in the tank (some more than others).
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  9. #9
    That's all folks! Gary Slusser's Avatar
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    Bonnie, it's a water or air quality thing and has nothing to do with the toilet type unless there is 'rubber' deteriorating in the tank; again due to water quality. How will you feel after replacing these toilets and still having the problem? Are you on well or city water? City water with chlormines in it is very hard on 'rubber' gaskets and seals. It causes black smears that are hard to get off, so I suspect you have some type of air borne something.

    Gary
    Quality Water Associates

  10. #10
    dc_homeplumber
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    And, like them or not, low flow toilet are now "traditional." Unless you get illegal imports from Canada that still flush with 3.5 gallons, in the U.S. we're stuck with 1.6 gallons (and some newer ones even less).

  11. #11
    Plumber, Contractor, Attorney LonnythePlumber's Avatar
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    Cool Rubber Dissolving

    I relate these complaints to rubber dissolving somewhere in the system. While you maybe only notice the black marks in the toilet bowls they may also be occuring at other fixtures but because the water does not sit, it is not noticable. I would take Jim's suggestion to let a glass sit.
    I would not think the residue is due to the toilets. More likely it is related to the toilet supply tubes if it is not occurring at other fixtures.

  12. #12

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    I will try jadnashua's suggestion and let water sit in a clean cup for a week to see what happens. I will post the results of my "experiment" next week.

  13. #13
    Retired Defense Industry Engineer jadnashua's Avatar
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    Someone else suggested it, but you may have missed it - many people use the flexible hoses to connect their toilets to the shutoff valves. Some of these are better than others. Some places also sell some that are not rated and certified - thus, the quality of them and their components may be suspect. They're only a couple of bucks - you migh want to consider replacing it since the interior of the hose may be the source of the black marks.

    Also, take the top off of the tank, and lift up the flapper valve. See if you have black crud on it. If you do, replace the flapper valve. This rubber may look okay, but be deteriorating. I've seen some that just felt slimy, not from contaminants, but just from decomposing in the water. Rub your fingers over both the top and bottom of the flapper valve. And last, the rubber bushings that go around the bolts thathold the tank to the bowl could be in the same state - i.e., soft and slimey. They may need to be replaced.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  14. #14

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    The customer service department for the house builder has arranged for someone to come to my house tomorrow to test the water in the water heater. I have not spoken to this person directly, but I was told by customer serivce that perhaps there is bacteria in one or both of my water heaters causing gunk to come out the toilets!?! If that is true, then my drinking water must have gunk also! Can water heaters that are only a few months old become contaminated like that? If so, what are the options to correct the situation?

  15. #15
    Plumber, Contractor, Attorney LonnythePlumber's Avatar
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    Cool Hot to Toilet?

    Water from the heater does not go to your toilets. There is either a major miscommunication or you're talking to the 3 stooges. I cannot believe the service department of your builder includes a licensed plumber.

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