S-trap toilet bowl vs P-trap toilet bowl – Which is better?

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In an HDB flat, depending on the bathroom design, there will be different kinds of fixtures that will be connected to the sewerage system. These fixtures include the sink, HDB toilet bowl, tubs, shower, and others. The plumbing system for these fixtures usually includes a trap. The trap may be an s-trap or a p-trap – depending on when the HDB toilet bowl was installed. If a homeowner is planning to install or replace his HDB toilet bowl, then he should know the importance of a trap and how to select one.

Here are the things you need to know about toilet bowl traps:


Functions of a trap

The drainage pipes in a home are connected to the sewerage system which produces a large number of gases like carbon monoxide, methane, hydrogen sulfide, and nitrogen. Some gases like carbon monoxide do not have any odor yet are extremely toxic, while the other gases have an unpleasant smell. It will be dangerous and difficult to live in the house if these gases enter inside. Also, if there is a direct connection to the sewerage system, vermin could enter the house. Therefore, a trap is installed to prevent these from happening. Although there is a difference between a wall mounted and a floor mounted toilet, the one thing they have in common is having a trap. The water will gather in the trap and act as a barrier to block the gases and vermin. If any larger item falls in the drain pipe accidentally, then it will remain in the trap.




The simplest type of trap used in the plumbing system is an S-trap toilet. The trap is shaped like the letter S and was used in earlier installations in almost all plumbing systems. The water accumulates in the bend of the S-trap and blocks the gases when it is filled. However, if the S-trap is not being used for a long time, the water inside may evaporate causing a space through which the toxic gases from the sewerage system may enter the house. Though this issue can be easily fixed by pouring some water in the toilet bowl or sink connected to the S-trap, in a few cases, the gases have created problems. This is why in some countries, S-traps are prohibited to use for newer toilet bowl installations.




On the other hand, the P-trap toilet is used in newer buildings and constructions since it overcomes most of the problems caused by the S-trap. The P-trap toilet is curved – it goes down, rises, and is then straight for some distance before being connected to the main drainage pipe. A properly installed P-trap will never become dry and will withstand all conditions. The waste gases will exit through the vents as the P-trap is usually vented. Consider installing the Baron W888 if you are looking to buy a P-trap toilet bowl.


Which type of trap to choose for your HDB toilet bowl?

Most homeowners have an S-trap HDB toilet bowl installed as most HDB flats have a drainage outlet placed on the floor. However, it would still be beneficial for you to replace your HDB toilet bowl with a P-trap toilet bowl by installing a concealed cistern and getting a professional plumber to assist you.



It is important to know the functions of your toilet bowl, especially your toilet trap. This is to avoid any common toilet bowl problems from happening such as preventing harmful gases and vermin from entering your household. There are two types of toilet bowl traps – the S-trap which is the simplest type of trap used in earlier toilet bowl installations, and the P-trap which is durable and used for newer toilet bowl installations. In choosing which kind of trap is best for your HDB toilet bowl, it is recommended to acquire the services of a professional plumber as they have extensive knowledge in this area.


At Toilet Bowl City Singapore, we understand the need to keep home service expenses within your budget. Hence, we offer honest and reasonable pricing for any of your toilet bowl installations works. Select from our range of toilet bowl brands, browse our past toilet bowl installation projects for inspiration, or read up on toilet bowl-related articles to find out more about toilet bowl installation services. Get in touch with us now via WhatsApp at +65 8241 0032!