Venting pipe in domestic water system. All aspects of plumbing questions and answers, help, tips and information

[grakar]

A pipe rises from the waste water pipe from our bathroom sink and goes through the roof I assume for venting purposes. This pipe encroaches on space I need for a vanity unit and I wonder if it can be removed. As I understand it no smell can come up through the sink as there will be a trap fitted. What please is the function of this pipe and can it be removed?

[jim the plumb]

You are probably talking about the 4inch soil pipe that extends through the roof to the open air. This pipe vents smells from the toilet/ waste drains to open air.

You can fit a 'durgo', or 'air admittance valve' by cutting down this 4inch pipe, but the valve must remain higher than the highest waste in the bathroom. i.e. the basin.

HTH, jim

[grakar]

Thanks Jim for your reply.
The waste water from the basin in addition to venting through the roof is piped to a rainwater down pipe. This pipe is open to the rainwater gutters on the roof. Do I need further venting? The soil pipe from the WC is fed to a separate downpipe.
grakar