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What is a soil and waste system?

Soil and waste systems carry used water from appliances into the underground drainage system. These appliances include washing machines, dishwashers and the like, as well as sinks, basins, baths and toilets. But what is a soil and waste system made up of? The key components of a soil and waste system are as follows.

what-is-a-soil-and-waste-systemSoil systems

In domestic installations, soil stacks are generally 110mm in diameter. There are two options for jointing, push-fit soil pipes and solvent weld soil pipes.

Push-fit systems have ring seals in the sockets of pipes and fittings. They push together with the use of lubricant. Solvent weld systems use a solvent cement. This cement is applied to the inside of the fitting socket and the spigot, ensuring a secure joint.

Waste systems

Similarly, waste systems are offered in push-fit and solvent weld options. Diameters are generally termed as 32mm, 40mm and 50mm. However, solvent weld systems have a larger ‘metric’ diameter to that of the ‘imperial’ push-fit range. Different material are also used between the two: polypropylene for push-fit and MuPVC for solvent weld. For these reasons, the systems cannot be mixed.

Also available is a compression waste system, which has fittings with nuts that compress the fitting seal against the pipe spigot when tightened.


For every appliance in the system there must be a trap, which prevents foul air from reaching habitable space. Water remains in the trap and effectively blocks the passage of air.


Finally, an overflow within the system transfers water that may otherwise overflow inside the dwelling, through the external wall or roof space.

Soil systems are regularly fitted externally, so a choice of colours is available to blend (or contrast) with the external design of the dwelling. The Brett Martin Soil System is even available in their cascade cast iron style range, offering an excellent cost effective installation in more traditionally designed buildings.

Soil and waste systems are available to purchase here at Drainage Superstore. For more information about purchasing the correct soil and waste system components for your project, contact our helpline on 01752 692 221.


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