What is a S -trap?

There are 2 types of traps used in a plumbing drain line, for draining of solid waste from a W.C. into the drain line.

The first is a S trap, where the trap is like the english letter S, which is lying horizontal, and where the solid material from the W.C is flushed out by the force of water and the S trap ensures that the solid does not flow back into the W.C.

The disadvantage of this type of a trap is that the drain line of this trap passes on the base slab of the W.C. which may lead to leakages / seepages in the future, when the joints of the trap open up after a long period due to wear & tear and ageing of the cement used for filling the joint.

The second type of a trap is the P trap, which is like the english letter P, which is lying horizontal.

The advantage of this type of a trap is that the drain line of this trap passes through the wall directly and not along the base slab, thereby reducing the chances of leakage / seepage in the future.

I hope the answer resolves your query.