10 days ago I moved into a newly built house, with all new fixtures and fittings. In the past few days overnight in the downstairs toilet, brown sediment settles at the bottom of the pan. The water in the cistern is absolutely clear. This is not happening in any of the other toilets upstairs in the house. We have cleaned the cistern and toilet out, tried to clean around the u-bend and there is no obvious damage anywhere. There are no rusty pipes anywhere. Any ideas ?

  • 1
    What kind of pipe? What's the water source? What part of Earth?
    – isherwood
    Feb 17, 2021 at 22:01
  • Give it time the rust and sediment will eventually make it up to the upstairs throne room. You can have all copper or plastic but most city water systems have some old rusty cast pipes and it will get there eventually , especially after a power / pressure loss at the pumping station this stirs up the water in the pipes. Perhaps the lower bath was used during the worst supply time. It happens.
    – Ed Beal
    Feb 17, 2021 at 22:20

2 Answers 2


If on a well: While it's odd to have it only at one toilet, it otherwise sounds exactly like "clear water iron" (dissolved iron in the water, turns to rust when the water is exposed to oxygen.) That will pass right through a filter unless it's oxygenated first.

Try filling a clean white bucket with clean water, and then wait (or stir and wait.)

Or, check your water test results for iron and manganese.

If not on a well, check your aerator screens in the downstairs faucets, particularly.

You may be getting sediment or rust from the water distribution system, in which case a whole house filter should clean that up. You may not see it upstairs yet because it may be settling out more in the lower pipes.

Try filling your clean white bucket from the lowest drain valve or hose bibb in the house, or from the lowest sink with aerator removed. You probably won't have to wait long for it to settle out if this is debris, rather than clear water iron.


I assume you have well water; it contains soluble ( ferrous, +2) iron. When exposed to air it oxidizes to insoluble iron ( ferric, +3), which settles as a reddish gel like material. As answered by @Ecnerwal, it can be removed by oxidation and filtering. I had it in a house at one time with this condition, but with 5 people using the toilet, the iron had little time to form and settle in the toilet so I took no action.

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