Hi all,

Do modern WC systerns still need an external overflow pipe? I've been wondering for years why they don't just overflow down into the soil exit pipe and save boring extra holes through outside walls and whatnot. Now I have a Geberit wall frame unit to install and can't find any mention of overflow in the instructions, so I'm guessing maybe it doesn't need one due to this. Can anyone clarify the situation? I admit to being very out of date on this subject!

Thanks.