What Waste Trap Do I Need?
Waste traps are a crucial fitting in residential and commercial waste pipe systems as they prevent drain odours from escaping into the building. With so many different types of traps, it can be hard to know which one you need or which ones are suitable for each appliance. In this guide, we'll go through the various fixtures and furniture items in the house and discuss which waste traps are the most effective for them. We'll also specify what is needed to comply with UK building regulations for each appliance where necessary.
Baths
When it comes to bath waste traps, they are named as such so are easy to find, however, there are multiple types that serve slightly different purposes.
- Shallow bath trap - These are a popular type of bath waste trap that are designed to be used in applications where there is a limited amount of underfloor space in the bathroom. They feature a 20mm seal.
- Low-level bath trap - Though the name may make it sound similar to the shallow version, the low-level bath trap boasts a 50mm water seal for added protection against potential waste pipe odours. Whilst they do feature a compact design, they will require a little more underfloor space to be fitted.
Document H of the UK Building Regulations dictates that traps in baths are required to have a minimum seal of 50mm, which is likely to be the case the majority of the time, but 75mm is allowed if there is enough space for a larger trap.
Basins
There's a larger selection to choose from when it comes to fitting a waste trap for a bathroom basin, which helps to accommodate for a variety of basin designs and configurations.
- Bottle trap - The compact design of bottle traps makes them the ideal choice for a basin where space is limited.
- P trap - P traps are the most common choice for a basin trap and are the preferred option where space permits their use, as they known to be more robust and durable.
- Anti-syphon bottle trap - A specialist type of bottle trap, these are used to prevent the water seal from being drawn away into the waste pipe via siphonage, which is more likely to occur in waste systems with a long pipe run. Their design also prevents gurgling sounds from occurring when water is drained away.
Since basin traps need to handle soaps and minor debris as well as water, they are required to have a minimum water seal of 75mm to ensure that odours are effectively prevented from entering the room.
Showers
Shower traps are generally the smallest type of trap and therefore feature compact designs. This is due to the fact that they usually must fit beneath modern shower trays which is a very tight space.
- Standard shower trap - The standard type of shower trap is a small cylindrical trap that features an outlet protruding from one side and an inlet on the top. The inlet is covered by a grid, the size of which can vary, but it is removable to allow for easy maintenance of the shower tray.
- Shower gully - Shower gullies serve the same purpose as shower traps, but they are used in wetrooms or disabled bathrooms and are fitted into the floor rather than a shower tray.
Similarly to baths, shower traps must have a minimum seal of 50mm, which can be found on standard shower traps. However, a 75mm seal can also be used, which is what shower gullies feature.
Kitchen Sinks
For kitchen sinks, we would recommend the same list of traps that are used for basins, being that they are very similar fixtures. However, each type serves a slightly different purpose in the context of a kitchen sink trap.
- Bottle trap - The ideal trap type for sinks with minimal space underneath, though due to their small size, they are slightly more prone to clogging from food debris.
- P trap - As with basins, P traps are usually the desired option when there is adequate space, since their larger size provides a better resistance to durability.
- Anti-syphon trap - The anti-syphon variations of bottle and p traps can be used on kitchen sinks, which is more common when the sink's waste pipe is coming horizontally out of the wall rather than vertically up from the ground.
Since kitchen sinks deal with some of the stronger substances that will go through a trap such as grease, chemicals and food waste, it is important to fit a reliable trap that can easily be cleaned and has a high flow efficiency. To follow UK Building Regulations, sink waste traps require a minimum seal of 75mm to prevent foul odours from escaping.
Washing Machines
Washing machines and similar appliances drain large volumes of water very quickly, and as such they require specialist traps that are specifically designed for them.
- Standpipe washing machine trap - This trap is used when the washing machine or other appliance has its own waste pipe connection, which is common if it is located in a utility room or basement.
- Appliance half trap - A half trap is used when the washing machine's outlet needs to be connected to the kitchen sink's waste pipe.
- Washing machine tee - Whilst not a trap itself, the washing machine tee is an important fitting in the context of traps since it is used to create a connection between a sink trap and a washing machine trap.
To be in accordance with regulations, an air break, which is essentially a vertical gap between the standpipe and the outlet hose, must be in place to prevent back-siphonage from occurring.
We hope that this guide has assisted you with picking the right waste trap for your project, but if you require any further assistance, please feel free to get in contact with us.
