Waste pipe guide
By Tom Drake | 25th June 2024 | 4 min read
In this guide, we take you through the most common waste pipe sizes found around the home, and the different types of waste pipe connections you can use.
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Waste pipe sizes
In your home, you'll usually need either a 32 mm or a 40 mm waste pipe. Here, we outline the uses of these sizes and some of the other sizes you might see.
32 mm waste pipes
Used for:
• Basins
32 mm waste pipes are used at points where a low water volume will be entering the system. In the home, this is usually just bathroom basins.
40 mm waste pipes
Used for:
• Baths
• Showers
• Kitchen sinks
40 mm waste pipes are used in areas where higher volumes of water will be entering the system such as baths, showers and kitchen sinks.
21.5 mm waste pipes
Used for:
• Toilet overflow
• Boiler condensate pipe
Smaller 21.5 mm waste pipes are mainly used for toilet overflows or boiler condensate pipes.
50 mm waste pipes
You may also see 50 mm waste pipes. These are mainly used in larger commercial buildings rather than residential properties.
Push-fit waste pipes
Push-fit is the easiest type of waste pipe to install. Here, the pipes are simply pushed into the connector to form a tight seal without the need for any chemical bond.
As push-fit connections don’t chemically bond the pipes together, if you make a mistake, you can easily take the pipes apart and rectify it. This makes push-fit a popular choice for DIY plumbers.
Solvent weld waste pipes
Solvent weld waste pipe systems use a solvent cement that’s applied to the connector and the pipe to chemically bond them together. This creates a strong, permanent connection.
Solvent weld waste pipe systems will take longer to install than a push-fit system, and as the connection is permanent, it can be difficult to fix issues if you make a mistake. As solvent weld connections are more permanent than push-fit, it’s the best connection to use if there’s a chance a pipe could be knocked out of place.
Can I change between push-fit and solvent weld?
Push-fit and solvent weld waste systems use slightly different sized pipes. If you’re updating your plumbing system, you can change the connection type using either a conversion fitting or a universal compression coupler.
What is the difference between soil pipes and waste pipes?
Soil pipes differ from waste pipes in the different material they carry. Soil pipes are designed to carry soiled water (blackwater) away from toilets. Waste pipes are designed to carry ‘grey water’ away from showers, baths, sinks, washing machines and dishwashers.
