Traps FAQs

Have a question on our Traps product range, then take a look at our frequently asked questions below. Still can't find what you are looking for? Call our Technical Services team on 01622 82695.

Traps Frequently Asked Questions

What product can I use to prevent gurgling noises coming from my trap?

You can use either the 32mm/40mm Gurgle Master or 32mm/40mm Anti-siphon unit to prevent gurgling noises.

How can I comply with Building Regulations when fitting a trap underneath a shower tray or bath where space is restricted?

Modern shower trays leave only a small gap underneath for the long suffering installer to fit a an effective waste trap. Sometimes it can seem like the only possibility is to cut a hole in the floorboards, but that’s not always possible on concrete floors or where structural joists are in the way.

BS EN 12050 has a requirement for water seal traps for baths and showers downwards to 50mm. This was permitted because showers and baths have flat bottoms that allow a small amount of waste water at the end of discharge to refill the water seal in the trap and prevent the seal being broken.

That reduction in the water seal requirements at least gives installers a chance to fit a trap that meets the standards. Although it is possible to fit a running trap away from the shower tray which will give the required seal, this can be awkward because it will need extra fittings to complete the job and it still needs to be hidden away from sight afterwards.

A solution is to fit a shower tray trap that is designed for the job, like the compact Multikwik shower trap. By designing the trap with an elongated water body, Multikwik has a 50mm water seal depth in a trap that is just 90mm deep, allowing it to sit beneath most modern shower trays.

What is a utility trap and what are its benefits?

Utility traps can take the waste not just from a sink but also from a washing machine and dish washer.

There is no reason why one trap (usually called a double bowl kit) can't take wastewater from two adjacent or combined sinks and, if they have the correct nozzle configuration, from a dishwasher and washing machine.

What can I do to avoid siphonage?

Siphonage occurs when negative pressure draws air into the waste pipe as the waste water from a bath or basin discharges and pulls the water seal from the trap with it. There are three types of siphonage:

  • Self-siphonage - discharge from an appliance causing a loss of seal in its own trap 
  • Induced siphonage - the seal loss is because of the discharge of another appliance connected to the same waste pipe 
  • Compression siphonage - a falling body of water in a vertical pipe compresses the air below it and forces the water seal from lower appliances traps.

In some circumstances, where siphonage is occurring because of the pipework arrangement, but secondary ventilation is not possible, it is advisable to use a resealing trap. By drawing air in through the waste outlet before the water seal is dispersed, it counteracts siphonage before it can threaten the seals integrity.

However, resealing traps can be noisy and do not completely eliminate water sealloss. To prevent this, the Multikwik anti-siphon unit allows air to enter the waste system as pressure drops while waste water discharges.

Why do you have traps with different water seal depths?

BS EN 12056-2:2000 requires that traps discharge that to a soil stack have a 75mm seal however other water seal depths can be installed as follows:

  • 50mm Water Seal - Can be fitted to baths, shower trays and basins with spray taps and no plugs.
  • 38mm Water Seal - Can be used on ground floor’s when connecting to flat bottomed appliances that discharge to a back inlet gully.