Geberit Alpha or Sigma Concealed Cistern

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Sheepshanks

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• 18 Jun 2026

• #1

Hi all,

I'm looking to install a Geberit concealed cistern and I'm a bit lost on whether I should be going for the Alpha or Sigma cistern? Are there any major differences between the two?

Thank you

 

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DH GB

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• 19 Jun 2026

• #2

They both have a single blow-mold cisterns so are safe behind the wall. The main difference is setting up infrared touchless flush is easier with Sigma, and you have a choice of 130ish different flush plates with Sigma many of which are metal (and nicer) whereas Alpha's are plastic, still durable but plastic. Sigma is easier to install due to a lot of tool-less maintenance features.

 

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Sheepshanks

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• Saturday at 4:32 PM

• #3

DH GB said:

They both have a single blow-mold cisterns so are safe behind the wall. The main difference is setting up infrared touchless flush is easier with Sigma, and you have a choice of 130ish different flush plates with Sigma many of which are metal (and nicer) whereas Alpha's are plastic, still durable but plastic. Sigma is easier to install due to a lot of tool-less maintenance features.

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Thank you for getting back to me. This is great information, thanks. I don't think we'd be looking at implementing an infrared flush. The flush plates do look much better for the Sigma system. Not sure if I'm looking in the wrong place but is it normal for the Sigma flush plates to be more expensive than the frame? At the moment, for an Alpha cistern/duofix frame with plastic brass flush plate its coming out at roughly £210. For the Sigma cistern/duofix frame with stainless steel brass effect plate it's roughly £510.

 

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DH GB

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• Saturday at 4:42 PM

• #4

That is probably right, but when you hold that Sigma Flush plate it is nice... And it's only 4mm thick if it's the one I think you mean, whereas the Alpha is 16mm. but both the Alpha and the Sigma get great reviews.

 

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opps

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• Saturday at 6:12 PM

• #5

I dunno. I am not a plumber... but when my gerberit concealed system started to drain in the bowl, I discovered that the rear of the flush plate had a spare washer. That made my life so much easier. There was a second, smaller washer, I don't know what that was for, but the larger washer resolved the problem. From memory, the original rubber washer last over 15 years.