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What are waste traps and how do they work?

Ever wondered what happens to the water when you flush the loo or unplug the bath or sink? The simple answer is it is disposed into the foul water drainage system which deals with a lot of waste. This often leads to a build-up of nasty odours that you don’t want to enter your property.

However, as a general rule of thumb, all water-using appliances and fittings within a property must have a waste trap to provide a water seal to the drains.

Here we explain what waste traps are and how they work in layman’s terms. So, if you’re thinking about installing a new bath, sink, washing machine or dishwasher, read on to find out more about these essential parts.

What are waste traps?

A waste trap is a small yet crucial part of the drainage system that connects from an appliance in your house to the drain. It is filled with water and prevents smells, bacteria and insects from entering the property.

Traps come in various shapes and sizes – and you’ll be pleased to know that we stock an extensive range of universal sink and bath waste traps here at Total Pipes.

Different types of waste trap:

  • P traps

These normally have a horizontal waste outlet and screw joint halfway along so they can be easily removed to clear a blockage without disturbing the pipework. It also means that the outlet can be adjusted to accommodate the position of the waste pipe that’s connected to it. The only downside to P traps is that they require a fair amount of room around the waste outlet.

  • Bottle traps

Much like P traps, they have a horizontal waste outlet but the lower half unscrews to allow debris and blockages to be removed. These waste traps take up less room under a waste outlet and are ideal for pedestal mounted basins where space is often limited.

  • S traps

exactly as their name implies, these are manufactured in an ‘S’ shape and have a water outlet that points downwards. Adjusted via the centre swivel joint, you can easily align it with the drainage pipework. Its free-flowing shape enables water to drain away quickly – preventing the accumulation of dirt and, in turn, preventing blockages. S traps require more space than bottle traps.

  • Shallow traps

Made to fit under the confined spaces commonly found with baths and showers. When connected to a bathtub, a banjo connector is usually required for the overflow. Unfortunately, shallow traps may not meet the depth of water seal required by the water regulations. So, if there is no other alternative, you may need to fit another trap further along the pipe run (where space allows) and before the pipework enters a stack pipe or discharges.

How do waste traps work?

Although there are several types of waste trap, the principle remains the same.

When you flush the toilet or drain the sink or bath, the water is taken outside of your house where it connects with the main drainage. The foul drainage system deals with everything except for rainwater and, with a great deal of toilet and bathroom waste, foul gases soon build up.

These gases try to escape back up the pipes or through any other aperture within the system and, if they succeed, they could end up in the room where they came from (i.e. your kitchen or bathroom). This is why you need a waste trap.

For the waste trap to work, it needs to have water in it. The water will sit in the U bend – just below the level of the outlet bend – and essentially block gas from making its way back up the pipework. When more water is introduced from the incoming pipe, it will replace the water that’s already in the trap and push it out of the outlet.

And there you have it. You should now have a better idea of the different types of traps you can buy and how they work.

Get in touch

If you have any further questions about waste traps or would like an expert opinion, please don’t hesitate to contact us. Our team has unparalleled knowledge of the products available and will happily advise you on the best for your application. Just give us a call on 01254 382 000 or email, and we’ll get back to you.