Shape of Old 1970s Toilet Cistern

Eeeeewww !!! You did say you were refurbing the toilet didn't you .? :-)

wall, but more or less in the centre. Don't know what it's there for though.

Manufacturing feature? Something that helps during the kiln firing?

"Stuart B" wrote

Don't worry Stuart, since that pic was taken, the cistern has been demounted, bleached out and all the old internals stripped. The syphon was a solid and serious piece of kit. Far more rhobust than the modern offerings.

Phil

And my old Armitage Shanks ??

Andy

It's so the overflow can be taken straight out the back if desired (althgough no-one ever bothers!)

I withdraw that remark as it's stupid! Too late in the afternoon. One feels it's for a pipe of some sort though.

The same on my fairly recent Armitage Shanks.. :-)

I think it is the 'last chance' overflow. My Alia has a similar feature. Presumably if the overflow (Warning Pipe) is blocked it will cause the water to overspill down the back on the off chance this might be preferable to spilling all around the lid. It will also limit the weight the cystern may have to hold.

I would agree until I popped the lid off my cistern to have a look. Mine has the curved cut out along the central 2/3rds of the lid, too big to be for a pipe.

Adam

Probably curved inwards to allow for crap plastering/tiling behind it causing a high spot, which when mounting screws are tightened would cause said cistern to break its back.

and even more importantly, prevents the lid floating on a full-to-the-brim cistern and possibly slipping off.

I have assumed that these recesses were to allow air to enter the cistern during flushing. On some models the lid fits pretty well and without this opening the flush could be seriously reduced by the partial vacuum during flushing.

I don't think plastic cisterns have such a cutout; have they? Some plastic ones have a lid which is attached by screws and must be even more airtight.

That sounds like a very good reason.

I can't see the back, but looking up from the bottom of the cistern there also seems to be some sort of a shallow channel up to the cutout.

In message , TheScullster writes

My Villeroy & Bosch cistern has this and it's used for bringing a hidden pipe (buried in the wall) into the cistern. There's a stop valve attached to the in-wall pipe with the filling mechanism hanging on it.