Western Toilets (EWC): S Trap vs P Trap and How to Choose

EWC means European Water Closet, the floor-mounted western toilet most Indian homes now use. You can buy the bowl on its own with a separate cistern, as a "couple closet" where the cistern bolts onto the bowl, or with a concealed cistern hidden inside the wall. Before choosing any of these, you need to know one thing about your bathroom: is the drain S trap or P trap?

S trap vs P trap

Every toilet has a trap, a bend that holds water and blocks sewer smells. What differs is where the outlet goes after that bend.

S trap is very common in Indian homes because many houses were built with the drain line running under the bathroom floor. The toilet sits directly over the hole.

P trap suits buildings where the waste pipe runs in the wall or through a shaft, as in many apartments. The outlet comes out horizontally at the back and connects to a pipe in the wall.

How to check which one you have

1. Look at the back of your current toilet at floor level. If you see no pipe and the bowl sits flat, it is almost certainly S trap.
2. If a pipe or connector goes from the back of the bowl into the wall, it is P trap.
3. In a new bathroom with no toilet yet, check where the plumber has left the open pipe: in the floor (S) or in the wall (P).
4. Measure from the finished wall (after tiles) to the centre of the floor pipe, or from the finished floor to the centre of the wall pipe. Note it down and bring it to the shop.

EWC sizes and couple closets

Typical sizes vary by manufacturer, but as a rough guide:

• Floor-mounted EWC (bowl only): about 510 to 570 mm long, 350 to 445 mm wide and around 400 mm high. The cistern is bought separately, either wall-mounted above or concealed inside the wall.
• Couple closet (two-piece): the bowl with a cistern bolted on the back, usually about 685 to 710 mm long and around 800 mm high including the tank.

If you prefer a single fused unit with no tank joint, see one-piece toilets.

Concealed cisterns

A concealed cistern sits inside the wall or behind a false wall, and only the flush plate shows. It works with a floor-mounted EWC or with a wall-hung toilet that floats above the floor. The bathroom looks cleaner and you can mop under a wall-hung bowl easily. Plan it before tiling, since the frame and cistern must go in while the wall is open, and make sure the flush plate gives access for future repairs.

Health faucet and other points

• Health faucet: most families want one. Ask your plumber to leave a water point on the wall beside the toilet, at a comfortable reach, before the wall is tiled.
• Seat height: standard bowls suit most people, but elderly family members often find a slightly higher seat easier. Add a grab bar on the side wall if needed.
• Floor around the toilet: use anti-skid tiles, since water from the health faucet often lands on the floor.
• Space: leave clear room in front of the bowl and keep the wash basin from crowding it.

If someone in the family still prefers squatting, an Indian toilet in a second bathroom is a common solution. For tiles that go with the toilet, see our bathroom page.

Check what fits your bathroom

Note whether you have S trap or P trap, bring your measurements and contact the shop to ask which EWC and couple closet models are in stock.