Non-motoring > Strange flush Miscellaneous
Thread Author: Ambo Replies: 13

 Strange flush - Ambo
We had two new matching toilets fitted on first and ground floors in 2015. Recently the ground floor one has been acting strangely.

Randomly, but on average at ten-day intervals, the bowl has been found, hours after a normal flush, with the water level so low it barely covers the outlet rim, but never uncovers it completely. It would if there was a leak but it never has been uncovered, neither is there any foul smell a leak would cause. Flushing the bowl restores normal level, which remains normal pro tem.

The only cause I can think of is a temporary vacuum caused by a sudden rush of fluid past from my outlet to the common sewer from the two houses (of three) above mine, say if two baths were emptied at the same time. . This would cause water in the bowl to be sucked partially out. Can anyone suggest another cause?


 Strange flush - No FM2R
I have had this when there was a blockage. It was caused by the blockage slipping along slowly and periodically after a flush and sucking more water after it. It did not uncover the lip because each time it did so, air slipped through instead causing the water level to pop back up again.

A carp explanation I know.

A further indication was that the bowl filled up more than was normal at the time of flushing though it then drained down to what looked like the normal level with the barest delay.
 Strange flush - Zero
Its a blockage in the system, as mark says the syphon effect of drain emptying the blockage pulls the water out of the bowl. Happened to me a few times.
Last edited by: Zero on Tue 12 May 20 at 16:14
 Strange flush - maltrap
I assume the soil stack is vented, usually to the outside through the roof, sometimes internally when a 1 way valve is fitted, letting air in but not out. Might be a sticky valve.
 Strange flush - CGNorwich
Most likely a partial blockage in the drains leading to a vacuum effect I would say. if it doesn't
clear after repeated flushing you need to get the drains rodded. The only other think it could possibly be is a leak but you would be seeing evidence of this on the toilet floor.
 Strange flush - maltrap
Probably the dreaded Wet Wipes, they've been keeping Dynorod operatives in work for years.
 Strange flush - CGNorwich
True. Add some discarded chip fat and you can soon have your very own fat-berg.

Whilst not as bad as wet wipes ordinary Kleenex type tissues, unlike toilet tissue take a long while to dissolve too and can plug the drains when discarded en masse as I know to my cost.
 Strange flush - Falkirk Bairn
Washing soda +HOT water poured into toilet & flushed might just help.
We had some problems a few years back - plenty manholes in my garden but it did not fancy getting rods out. It work after 2 or 3 applications over a period of a few hours.
 Strange flush - smokie
... I'd agree with FB in the first instance, though I probably would just do a full bucket or three in quick succession and not cool it by flushing it.

One time many years ago when I had a suitable tap and hose connector I connected the hose to the hot tape and cleared a (what was probably paper) blockage just by poking the hose round the bend and letting the hot water run, not prodding with it.
 Strange flush - martin aston
Before you do anything elaborate its worth trying a simple water rush. You can do this by filling a very large bin with cold water and dumping it into the toilet bowl at the fastest rate it will accept. I have had past success in doing this. Depending on your drain layout it might be worth coordinating this into both toilets at once.

Obviously take care that you don’t flood the toilet room. I suppose too there is a risk of simply moving any blockage into a less accessible part of the system. Rods or a professional might then be required.

 Strange flush - Manatee
Presumably for the blockage to cause this it must be between the toilet and the soil stack, unless the blockage is after the toilet outflow and backing it up the soil stack higher than the crown of the u-bend - in which case you might occasionally see much higher water levels in the pan of the peccant toilet or even an overflow!

I feel an experiment with sequential and simultaneous flushings of the two toilets might illuminate this.

I am not a toilet expert.
 Strange flush - Zero
My blockage the last manhole before the road main sewer in front of it, and two toilets, three gray water traps and the Soil stack behind it.

So no it doesent have to be between the soil stack and the toilet. The bowl that syphons is the last one in the chain nearest the main sewer.


I clear my blockages by taping the hose to the end of the rods, and rodding it with water jet
Last edited by: Zero on Tue 12 May 20 at 20:14
 Strange flush - Manatee
Obviously I have much to learn about toilets Master Po.

I thought the soil stack should remain at atmospheric pressure?

 Strange flush - Zero
>> Obviously I have much to learn about toilets Master Po.
>>
>> I thought the soil stack should remain at atmospheric pressure?

In practise - Only one end of it some of the time.
Last edited by: Zero on Wed 13 May 20 at 08:17
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