A toilet cistern that doesn't leak

Ideally I'd like a cistern that flushes only as long as the button is pressed. I have installed one that does that already, but every now and then some moron manages to flush in such a way that the valve at the bottom of the cistern leaks slightly, or lifts the lid or the cistern half off the wall. The result is that the rainwater tank empties its 30 cubic metres of water into the toilet, and there's no water for anything until the cistern is fixed and it rains. I suppose some kind of syphon cistern would work except that it would do a full flush every time. Or if there was a part-flush mechanism the morons would manage to wreck it. Elsewhere I have a very old syphon cistern that people manage to flush with some weird action so the water runs continuously.

An idea has just occurred to me - to put a very heavy weight on the valve of the existing cistern.

Reply to
Matty F
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Reply to
Dave Liquorice

That might be hard to arrange with your limited water supply. B-)

I have installed one that does that already, but every now

Remove cistern. Provide a tap, that you have to hold on to get water, and bucket.

is the rain water supply well filtered before it gets to the cistern? Is crud getting under the flap valve?

Syphons, IMHO, tend to be much more reliable. One of ours will occasionally end up in that non-stop running state not quite sure how it manages it but it is related to trying to flush when the cistern is not completly refilled. Just a small amount of flush will stop it ie just enough to splash some extra water round the bowl not a full flush. I wonder if a small hole in the top of the syphon will cure it? I mean small, as in tiny, as in pinhole, just enough to slowly leak a bit of air in to break any partial syphon that is set up but not enough to upset the main flush syphon.

Might be worth checking how much play there is in the bearing of the flap and that it can't easyly catch on the sides as it drops back.

Reply to
Dave Liquorice

If "leaks slightly" is less than 0.5 l/min, this here might help:

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also sell more complex systems, but I'd suspect that the price would be too high for the benefit...

Thomas Prufer

Reply to
Thomas Prufer

I don't understand that. There is usually 30,000 litres available until the moron arrives..

We had two taps like that, very expensive. They were stolen for the brass content.

That's a possibility. Any reasonable person would notice that the water continues to flow, and would do something to stop it.

My syphon has such a hole. The size is critical. I've tried to find someone who knows how a syphon cistern *really* is supposed to work, but nobody seems to know. A moron can defeat a syphon cistern and make it run continuously.

There's a pipe that slides up and down in a tube, all plastic, with a flat rubber washer at the bottom. I can't see how it can go wrong. But faced with morons who take the lid off the cistern or pull the cistern half off the wall, anything is possible.

Reply to
Matty F

I have a cistern that fills up. Two other possibilities are:

  1. take the water from near the top of the water tank. If they stuff up the cistern at least it won't drain the whole tank.
  2. an electric valve to shut off the water if the power is turned off. But the morons will leave the power on. They are already supposed to turn the tap from the main tank off. But they don't. Perhaps there should be a penalty of 0 for not turning the water off, paid in advance.
Reply to
Matty F

Could you use a second, small cistern as a feed, filled manually by opening a huge valve connected to the first? I.e. a r

Look at the other clever things at the wayscale site -- here's a PIR that turns on the water when there's motion, and shuts it off with a delay when there isn't:

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They are already supposed to turn the tap from the main tank off. But

That might work where signs and appeals to common sense fail.

Thomas Prufer

Reply to
Thomas Prufer

The only way a siphon can run continuously is if you are filling the cistern as fast as the siphon can empty it. You need to restrict the flow so the water reaches the bottom of the cistern and the flow stops.

The hole in the pipe is usually for "dual flush". It is covered when the handle is held down and will give a flush that lasts until the cistern is empty, but is uncovered when the handle is released breaking the flow.

If people tamper too much, fit a concealed one behind the wall.

Reply to
dennis

Not strictly true. There is some way that our syphonic flush cistern can end up running continuously. It's not at full flush rate but still a noticeable flow down the back of the bowl and no it's not an internal overflow...

I can't get my head around how it does it, but it does.

Reading the OP's follow up that is probably the only real solution, deny access to the workings. Boxing in with 12mm ply on a sturdy well fixed frame should do it.

Reply to
Dave Liquorice

Ha! .nz not following a literal reading of the english and british sense of humour. B-) You don't say how long the button will be pressed for. It could be jammed pressed and with only 30,000l available it will run out so you can't have a flush that lasts "as long as the button is pressed".

Personally I push the flush and walk away to wash hands. I don't watch to see if the flush completely stops.

You seem to describe two different flush valves. My troll alarm is starting to sound. What you describe above is a normal syphonic flush mechanisium.

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good but isn't 100% accurate:

"The syphon continues to work until air is drawn into the cistern."

Should read "syphon" at the end. If air can't get into the cistern the water can't get out, full stop...

And they use the term "flap valve" when refering to the disc that lifts the water. Don't confuse this with a "flap valve" type of flush mechanisium where there is conical "flap" and coresponding shaped hole in the base of the cistern over the entrance to the down pipe. With this type a flush is created by simply lifting the valve open.

Reply to
Dave Liquorice

The moron jiggles the chain up and down several times in a random way thus triggering the continuous flush. The situation then appears to be that the cistern has half refilled with water, covering the small air vent hole half way up the bell. The pipe going from the cistern to the toilet bowl is full of water which is emptying into the toilet and sucking water out of the cistern.

The flush proceeds normally until the moron pulls the chain again.

In this case the cistern is around 130 years old and has no dual flush facility. The hole is half way down the syphon bell. It's there to allow air to enter so that the pipe to the toilet may empty of water and stop the flush.

The cistern that is the subject of this thread is concealed behind a wall. But people can walk around the back of the building to see it. Which gives me an idea - I'll put a big box around it and padlock it closed. And put a big weight on the valve so that it closes properly. Failing that I'll remove everything and they can have a pit toilet again complete with 12 inch cave wetas. These are what are lurking under the seat:

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Reply to
Matty F

Come on - let's have the jokes!

Reply to
PeterC

I had that problem - slackening the push-button a quarter-turn stopped it. It was just occasionally jamming slightly. If the button does jam down that's not the fault of the operator - there's nothing that one can do wrong with a button except hold it down for too long.

Reply to
PeterC

This cistern (the one with the leaking problem) is *not* a syphon cistern. The flat rubber washer covering the pipe to the toilet is just pulled up for a flush. The one at my house *is* a syphon cistern but is very old (in a heritage building so I don't want to change anything).

have here at home. Perhaps I can buy one like that. Mine is all cast iron. There are two moving parts apart from the inlet valve and float

- there's a big bell and a lever to lift it up.

Reply to
Matty F

Since the cistern is outside the building, I have removed the push button and replaced it with a pull cord that goes through a hole in the wall. There's a knot in the cord to stop it being pulled too far. I'll add a lump of lead to the valve to make sure it closes!

Reply to
Matty F

Except that the pipe leading to the bowl is quite large bore. I can't see what stops air entering that pipe from the bowl letting the water out of pipe and thus stopping any syphon action. Maybe some form of airlock in the down pipe?

Reply to
Dave Liquorice

The only syphon cisterns I have seen are very old ones and the principle is different (and rather poor I think). There is a large cast iron bell that is lifted up to raise the water. To avoid sucking air from near the bowl there is a U-bend at the bottom end that is full of water. Otherwise when the bell is lifted no water would be raised. In order to stop the syphon there is a small air hole half way up the bell.

Reply to
Matty F

Ah two bogs that's the confusion...

I'm not surprised a flat rubber washer leaks you need something that will self centre and have a large sealing area. A bit of sheet lead across the back of the flap may help but I think you'd probably be better off trying to find something like:

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Reply to
Dave Liquorice

Actually the rubber washer is centred quite well. Almost all cisterns I've seen here have a similar system. However dirt could cause a leak, and this toilet is in the middle of dense bush. I think I have invented a solution. I really only need a few litres for a flush, because the toilet is over a long drop and looks like this:

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will have a vertical pipe in the cistern with large holes in it near the top. Sliding on that I will have a plastic 3 litre box that may be pulled up so that water goes down the holes. Simple and can't leak and can't be blocked.

Reply to
Matty F

Common in the US, at least thats the impression I got when googling to find a page that described how a flush cistern works.

Why reinvent the wheel? How do you reliably get suitable seal(*) between the pipe and box and guide the box so it doesn't tip and jamb? How do you get the empty box to sink and refill in a reasonable time?

Are modern flush syphons not available in .nz?

They are:

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NZD137 - GBP54 They are about GBP12 over here!

Reply to
Dave Liquorice

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