Understanding the correct sizes for soil and waste pipes is important for keeping your drainage system functioning well and preventing clogs or leaks.
In this detailed guide, we’ll explore the various standard sizes and materials for soil and waste pipes. We’ll also offer tips to ensure a successful installation.
What is a soil pipe?
Soil pipes are pipes that carry sewage from the toilet, to the main sewer line. Unlike waste pipes, soil pipes transport both liquids and solids, so are therefore larger in diameter to allow for the higher load.
Soil pipe sizes
In the UK, soil pipes usually come in diameters of 110mm, as this is suitable for the volume of waste typically produced in homes.
However, larger pipes (up to 160mm) may be used in commercial buildings, where the facilities are used by more people and the volume of waste is higher.
Fittings and materials
Soil pipe fittings come in a variety of shapes and materials, often in PVC or with a cast iron effect. Standard fittings include bends, branches, and connectors that go around walls and other obstacles. PVC is a popular choice as it’s lightweight, affordable and easy to install.
How to fit a new toilet to an old soil pipe
When connecting a new toilet to an old soil pipe, placement is key, especially if you have more than one toilet. Avoid positioning a second toilet on the same horizontal pipe section as the first toilet, to prevent flushing issues.
First, you’ll need to measure the opening at the base of the toilet, called the flange, which connects the toilet to the drainage pipe. Cut your soil pipe to fit this measurement.
Next, add a slip coupling – a small fitting that enables you to adjust pipe connections – to the end of the soil pipe where it will meet the main drain stack. Then, attach the flange to the opposite end of the pipe using a push-fit connection, which slides on and locks in place.
Finally, move the slip coupling into position, connecting the soil pipe to the toilet flange securely. Seal both ends with additional slip couplings for a tight fit.
With proper tools and seals, you can avoid leaks and maintain a secure fit. It’s also a good idea to seek assistance from a professional plumber, or you can reach out to us here at Eurocell for advice.
What is a waste pipe?
Waste pipes carry water from sinks, showers, and various other appliances that don’t produce solid waste. These pipes connect to soil pipes or drainage systems, keeping wastewater separated from sewage.
Waste pipes tend to be smaller in diameter than soil pipes and are made from durable materials like PVC or ABS plastic.
Waste pipe sizes
In the UK, waste pipes come in three main sizes: 32mm for hand basins, 40mm for kitchen sinks, baths, and showers, and 50mm for commercial applications.
These sizes are large enough for the amount of wastewater that’s produced by each appliance, while minimising the risk of blockage. For example, for a shower, the standard size of 40mm diameter would be suitable.
Fittings and materials
Waste pipes use fittings similar to soil pipes, including bends, traps, and junctions. These are typically made of plastic, making them cost-effective, lightweight and easy to cut to length.
What is the difference between a soil and waste pipe?
- Purpose: Soil pipes carry solid and liquid waste from toilets, whereas waste pipes transport wastewater from sinks, showers and other appliances.
- Size: Soil pipes are generally larger (110mm) to accommodate solid waste, whereas waste pipes range from 32mm to 50mm based on appliance type.
- Installation: Soil pipes connect to main sewer lines, while waste pipes may join with soil pipes or separate drainage systems.
Installing a soil and waste system successfully
To install a soil and waste system effectively, you’ll need the right materials, pipe sizes, and an understanding of local building regulations. It will also need to be vented to let any gases or odours escape. Proper installation not only prevents leaks and water damage but also enables efficient drainage.
- Plan the layout
Identify where each fixture and appliance will be connected and select the correct pipe sizes for each.
- Cut and connect pipes
Use a pipe cutter for clean edges and connect pipes with the appropriate fittings.
- Check for alignment
Ensure that each pipe section slopes slightly downward for efficient drainage.
- Seal joints
Use solvent or compression fittings for a tight seal.
- Inspect
Once installation is complete, inspect all joints and connections for potential leaks.
How to fix a leaking soil pipe
A leaking soil pipe can lead to bad odours and water damage. First, you’ll need to inspect the pipe and find the source of the leak, which could be caused if your soil pipe isn’t properly connected with other pipes like drainage.
Small leaks may be fixed using a silicone sealant or PVC repair tape.
For larger leaks or cracks, you may need to replace the damaged section of the pipe. Be sure to turn off the water supply and wear appropriate safety gear before attempting repairs.
How to fix a leaking waste pipe
Just like a soil pipe, water damage could be a sign that your waste pipe is leaking. Before attempting to locate the leak, turn off your water supply and access the pipe.
Check for damage to the silicone or any loose components. It’s best to hire a professional because if there’s more severe damage, they’ll have the tools and skills to replace the pipe.
Can I unblock a soil pipe myself?
Unblocking a soil pipe requires a lot of caution. For minor clogs, a plunger or drain rod may help. Avoid using chemical drain cleaners as they can damage the pipes.
For more stubborn blockages, a professional plumber may be needed to assess and remove the clog safely.
Choosing the right size soil and waste pipe
Selecting the correct sizes for soil and waste pipes is essential to keeping your home’s drainage system working properly. Measure accurately and follow the standard sizes for each type of pipe.
You may also benefit from consulting with a professional for help with choosing other drainage products for your home.
By understanding the key differences between soil and waste pipes, choosing the right size, and following the correct installation steps, you can ensure reliable performance and longevity.
Explore our wide range of products at Eurocell, designed to provide excellent drainage and waste solutions. For more information, contact us today or explore our other guides for related tips and advice.