What is a Durgo valve?

Durgo valves, also known as AAV or air admittance valves, are valves that assist with rebalancing the pressure within a soil or waste pipe, returning this back to normal levels.

Why are they needed?

Every time someone flushes a toilet, both water and air are carried along the waste pipe, which creates negative pressure as additional air needs to be sucked in to replace this.

In order to create balance once more, air will be drawn into the pipe from other sources, most often from plugholes, and this can cause issues. These issues can range from gargling water from your drainage system right the way to unpleasant odours coming up and being released into the home. It can also result in wastewater bubbling up into your sinks or toilets.

How is this fixed?

Ordinarily, this would be fixed by including an open pipe outlet on your roof to pull in external air which would eliminate the possibility of odours escaping. This isn’t always possible, however, with certain roofs (the pipe must be 3 metres away from any opening window) and building regulations will sometimes not allow it.

In situations where this outlet cannot be used, a Durgo valve can be fit into your wastewater pipe system.

They are fitted using a push-fit joint and must be placed no lower than the highest exit point of any toilets, baths or sinks in your home – so the loft space is often the preferred place for installation. They can also be fitted outdoors in extreme circumstances where the pipe is too close to an opening window.

How does a Durgo valve work?

Durgo valves are activated once wastewater is sent to the waste pipe. As the pipe fills with negative pressure, the valve will open and allow air into the pipe. Once the pressure is equalized, the valve will close, which is what prevents unwanted smells from escaping and entering the home.

Why does my Durgo valve still smell?

Your Durgo valve could still smell when they fail. Often these failures are attributed to other causes such as if:

The valve has gotten stuck and needs lubrication
The vale has been fitted too low
There is an insufficient number of valves used in the property
The wastewater pipe is blocked

Your Durgo valve should be fitted in a place that is easy to access in case any of these are the case – the valve can then be inspected and the issue identified.

For more information on Durgo valves and your waste system, check out our guides and tips or talk to a member of our expert team.

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Items you will need

Soil and Waste Pipes and Fittings