What is a trap seal used for?
Trap seal opens to allow water drainage and closes tight when water flow stops. Aids in preventing the spread of bacteria that can escape from sewers causing potential health hazards. Prevents pests such as flies, cockroaches and rodents from crawling up through floor and shower drains.
Floor trap or Nahni trap is provided in to the floor to collect waste water from bathroom, wash area, washbasin, and kitchen sink area etc. It is normally made in 80 mm diameter and the depth of water seal provided is about 50 mm.
All plumbing fixtures need to have a trap. Inside a p-trap is 2-4 inches of standing water. This standing water is called the trap seal. The trap seal is what blocks sewer gas from invading into your home.
The photo below shows a “P-trap”, which is the type of trap you'll find below most sinks, showers, and bathtubs. Toilets have their own built-in traps, and so do floor drains.
The water trap seal is designed to act as a protection device and can be considered as a termination boundary. The water in the seal provides the barrier and by its design it is responsive through water height fluctuations, to pressure differential between the appliance and system side of a trap.
Each fixture trap shall have a water seal of not less than two (2) inches (51 mm) and not more than four (4) inches (102 mm), except where a deeper seal is found necessary by the Authority Having Jurisdiction.
This water creates an air seal that prevents sewer gas from passing from the drain pipes back into the building. Essentially all plumbing fixtures including sinks, bathtubs, and showers must be equipped with either an internal or external trap. Toilets almost always have an internal trap.
(1) Traps required. Each plumbing fixture, except listed toilets, shall be separately trapped by approved water seal “P” traps.
What Are The P-Trap Code Requirements? P-trap code states what is required for traps for toilets, sinks, tubs, floor drains, and other plumbing fixtures. If the p-trap is improperly installed, it will be more likely to clog with debris, cause water damage to a home, and even allow nasty sewer smells into the home.
The shower drainage features a piping that has a trap as part of its key components. The trap in the shower drain works like the one beneath the kitchen sink. While the sink trap is P-shaped, you may find some S-shaped shower traps.
Should showers have a trap?
According to regulations, all shower drains are required to have P-traps. This includes all fixtures connected to a building's main plumbing system. P-traps are curved pipes installed under showers and drains of all kinds.
If your vanity is wall hung, ideally you want the waste pipe to be coming through the wall and through the back of the vanity with a p-trap. If the vanity has depth, an s trap should also work. It all depends on how high the waste enters the back of the vanity.

- S-Trap or P-Trap. Basiclly, an S-trap is designed to outlet directly through the floor. A P-trap means the waste outlet through a wall.
- Setout. The setout of S-trap is the distance from the wall to the centre of the waste pipe in the floor. ...
- Entry / inlet. The entry is where the flush water enters the toilet cistern.
A standard urinal uses water to flush the urine into a pipe known as a “P-trap.” The shape of this pipe, which is not unlike the ones installed under most sinks in restrooms and kitchens, creates a water seal that prevents sewer gases from escaping into the restroom.
Even if you aren't a plumber by trade, you've probably seen the u-shape piece of piping under your kitchen or bathroom sink. This is a specific piece of plumbing equipment called a P-trap, and it is a necessary part of your home's plumbing system.
Any plumbing fixture directly connected to the sanitary drainage system must be equipped with a water seal trap. This means that every single plumbing fixture that is used to evacuate waste from a building must have its own plumbing trap. Deep seal p-traps have vertical depths of at least 10cm.
It is thus provided in the last manhole of the house drainage system and it has a water seal of 100 mm to prevent the entry of sewer gases from public sewer line.
noun. a small amount of water contained in the trap of a drain to prevent the passage of foul smells.
Each plumbing fixture shall be separately trapped by a water seal trap.
Bathroom wash hand basin wastes use a 32mm / 1-1/4 inch trap. Kitchen sinks, baths and shower wastes use a 40mm / 1-1/2 inch trap.
How far can a trap be from a fixture?
The vertical distance from the fixture outlet to the trap weir shall not exceed 24 inches (610 mm), and the horizontal distance shall not exceed 30 inches (610 mm) measured from the centerline of the fixture outlet to the centerline of the inlet of the trap.
A P-trap is required to be installed in most sink, shower, and bathtub drain lines by law. The reason P-traps are so essential is because they retain clean water in the drain line. This water seal stops horrible-smelling sewer gas from coming back up the drain line and into your home.
Does a bathtub need a P-Trap? Yes, you should always install a P-Trap as part of the plumbing of a bathtub or any other wastewater drain system. Failure to include a P-Trap could result in foul smells, harmful gases, and small animals entering through your tub's drain.
In a nutshell, a p-trap is a u-shaped bend in the waste pipe that connects a sink's drain to a home septic tank or to a municipal sewer system.
P-traps are S-shaped pipe components that keep toxic sewer gases from escaping into your residence. They are required on all plumbing fixtures, including sinks, tubs and showers.