Does Bathtub Drain need a Trap

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Under the sinks in your house, you can see a curving section of pipe known as a P-trap that serves a vital function for any plumbing fixture in a building. For example, bathtub and shower drains must have a P-trap; otherwise, sewer gases will enter the building, threatening the health and safety of people within.

In this regard, what kind of trap do you use for a bathtub?

It is a p-trap that is used on tub drains. As they have the same dimensions, the trap can be glued directly to the PVC drain pipe without the need for adaptors or fittings. It is recommended that the drainpipe is pitched 1 1/4 inches per foot.

Therefore, it is necessary to ask, how do you open a bathtub drain trap? To begin, remove the knob on the top of the stopper. Next, Hold the stopper in one hand and with the other hand, unscrew the knob by turning it counter-clockwise. Use the pliers to remove the knob if the knob will not unscrew. Next, wrap a rag around the knob and use the pliers to remove the knob.

Similarly, people wonder what the P trap in a bathtub looks like.

Because its shape resembles a sideways “P,” it’s called a P-trap. One of our customers recently had a bathtub drum trap replaced with a more efficient P-trap because it was outdated. Bathtub drum traps have the appearance of coffee cans. However, they clog easily and have limited effectiveness. P-traps, on the other hand, are used nowadays.

What makes an S trap illegal?

The purpose of a trap is to prevent sewer gases, and possibly vermin, from entering the house. However, as far as “S” traps are concerned, they aren’t allowed since they can leak water as water runs down the drain and is sucked out of the trap.

Shower traps prevent sewer gas leaks.

Not only do sewer gases smell bad, especially if they invade your home, but they also cause health problems when inhaled over an extended period.

It is carbon monoxide, one of the most dangerous gases that can come up through a drain pipe. Carbon monoxide still poses serious health concerns at low concentrations, even though it is fatal at high concentrations. According to the Centres for Disease Control and Prevention, carbon monoxide poisoning can cause headaches, dizziness, confusion, and vomiting. You are also at risk of dying from carbon monoxide poisoning if exposed to this gas for a prolonged period while you sleep.

According to the Wisconsin Department of Health Services, hydrogen sulfide, another sewer gas, can also poison people exposed to it. By causing oxygen in a room to decrease, the presence of methane can cause suffocation. If these health risks weren’t enough to make sewer gas avoidance a must, both methane and hydrogen sulfide would blow upon contact with open flames. All the residents of the house are at risk when sewer gases are present.

How Traps Provide Protection

You can protect your home from sewer gas leaks by installing a P-trap. It is expected that sewer gases will travel up drainpipes from the sewer and eventually exit the tub or shower drain if no obstructions are present. The P-trap will stop sewer gases from entering the drain line further up.

Since P-traps are curved, they will always hold water due to their curved shape. Thus, sewer gases will be trapped in the trap rather than moving through the water.

The Role of Vent Pipes

In addition to P-traps, vent pipes also play a key role in preventing sewer gases from entering your home. Gases from the sewer that can’t escape the P-trap go up the vent pipe on the house’s roof, which exits there. Venting is important for houses with septic tanks, as it prevents gases from building up inside them and posing a danger to the occupants.

Possible Shower Trap Failure

When the P-trap does not stay filled with water, it will not block sewer gases from entering the tub or shower drain. If the P-trap leaks or the connector below the P-trap opens, more water will drain from the trap until it’s no longer effective at blocking sewer gases. Eventually, the water will evaporate from the trap if no one uses the bathtub or shower often enough. In your area, the humidity level will determine how quickly water evaporates.

What Are The Benefits Of Installing A P-Trap?

Installing a P-Trap under a bathtub installation has a few important advantages. All of them are vital to your health and safety.

  1. Sanitation: The main reason is to prevent wastewater and sewage odours from backing up into the plumbing fixture.
  2. The installation of P-Traps in the drain pipes prevents hazardous gases from entering the bathroom. Sewage creates many harmful gases which can reenter the bathroom if not properly configured. Among these gases are:
  • Methane
  • Carbon Monoxide
  • Nitrogen
  • Hydrogen Sulfide


  1. The drain pipe coming down from the bathtub should be marked 1/2 inch above where it connects to the P-trap.
  2. Cut the drainpipe with a hacksaw straight across.
  3. Use a knife to trim burrs off of the plastic pipe.
  4. The location of the new bathtub drain on the bathroom floor needs to be determined.
  5. A new drain hole can be created on the floor using a 1/2-inch wood bit and a power drill.
    1. You should make the hole slightly larger than the pipe you will be able to fit through it.
  6. The bathtub should be positioned over the new hole with the drainpipe connecting to the hole.
  7. Locate the pipe that connects the P-trap to the coupling that connects to the main sewer line.
  8. This pipe should be cut straight across 3 inches beyond where it will slide into the coupling.
  9. Make sure the burrs left by the hacksaw are removed by using a knife.
  10. The end of the pipe that you just cut should be covered with plastic pipe glue.
  11. Attach the coupling by spreading glue along the inside.
  12. Hold the pipe steady for 30 seconds after in
  13. serting it into the coupling.
  14. If necessary, cut and glue pipe and coupling connections so that they reach beneath the bathtub drain.
  15. Glue the pieces together but don’t assemble the new P-trap yet.
  16. You will need to connect the P-trap assembly to both the tub’s drain line and sewer line.
  17. It is possible to glue the pieces together
  18. if the P-trap remains vertical during the dry fit.
  19. Disassemble the P-trap and cut the sewer pipe to adjust the fit if it is not vertical.
  20. You can glue the pieces together.

Do P-Traps Wear Out or Malfunction?

P-Traps can suffer from a few problems, causing them to malfunction or fail. However, proper installation of the plumbing system and proper ventilation can alleviate many of these problems.

  1. Siphonage: If the water in a trap is removed from a drain by suction power from other pipes, the trap could become dry. Whenever negative pressure is high enough, a siphon is created to draw the water from the trap.
  2. In contrast, positive pressure can cause wastewater to back up in a drainage system, causing the water to build up and blow past the P-Trap and into the fixture.
  3. In addition to water backing up, air bubbles can be forced up the drain, causing gases to enter the room
  4. even if no water is backflowing.
  5. Sometimes, strong winds can compromise traps by creating instances of siphonage and backpressure. For example, you may have noticed this effect when the water level in a toilet seems to rise and fall.
  6. Water evaporation, typically caused by low fixture usage, is perhaps the most common problem. In addition, an empty P-Trap can result in sewer gases building up in the drain and room; if you have a drain in your home that you do not use at least weekly, the possibility of a P-Trap failure increases.

Frequently Asked Questions

Is there a difference between an S trap and a P trap?

There is a bend in the pipe where the waste leaves the toilet called the “trap”. An S-trap exits directly from the bottom of the toilet and is intended for a direct outlet through the floor, whereas the P-trap is intended for an outlet through the wall at the back.

 Is a vent needed for the bathtub drain?

The plumbing vents on all drains are necessary to work properly, regardless of whether they are in a sink, tub, toilet, or floor drain. Drains without vents can be slowed down considerably. In addition, the drain will likely make gurgling noises. If the water in the trap siphons out, it can wreak havoc on the smellof sewers.

 Where should the P trap be located below the drain?

As per the International Residential Code, the maximum distance vertically between the sink drain and the entrance to the p-trap is 24 inches.

Do bathtub drains come in different sizes?

Down the Drain

Modern bathtub drains have a diameter of 1 1/2 inches — the width straight across the middle. For this reason, rough-in plumbing should be calculated for one 1/2-inch pipe. Antique bathtubs, like antique clawfoot tubs, usually have narrower drain openings, measuring one and a half inches or less in diameter.

How do you change out a bathtub?

Step 1: Pull out the drain. Unscrew and remove the overflow cover plate from inside the tub.

  1. Step 2: Disconnect the drain.
  2. Step 3: Disconnect the waste-and-overflow system.
  3. Step 4: Remove the tub spout and tiles.
  4. Step 5: Pry Away Tub.
  5. Step 6: Lift and Slide Tub.
  6. Step 1: Check the Drain.
  7. Step 2: Dry Fit Tubes.

Is it necessary to put a trap on a shower drain?

Following regulations, all drains in showers must have P-traps. In addition, all fixtures connected to the building’s main plumbing system must also have P-traps. Shower drains and curved pipes or P-traps serve other types of drains.

How far can the tub drain be from the vent?

8 feet

What is the best way to connect a shower drain to an existing drain?

Drain the new shower using plastic drainpipes and fittings, either PVC or ABS.

  1. Be cautious when working around water lines. If you are starting work near them, turn them off first.
  2. Locate and mark the existing drain and the spot where you want to install the new drain.

How deep is a shower trap?

Multikwik’s elongated water body design enables the trap to have a 50mm water seal depth in a trap that is 90mm deep. This allows the strap to fit comfortably beneath most modern shower trays.

 Does the P trap have to be directly below the drain?


The “P” trap SHOULD be directly under the drain, but no more than a few inches off-centre if conditions warrant it.

Where is the P trap in a shower?

The Ptrap for the shower is located below the shower drain hole. A P-trap may be one solid piece of pipe or an extension pipe attached to a J-bend pipe to form a “P.” Either way, P-traps are removed using the same method. It is essential to access the P-trap for the process

to work.

What does the P trap look like?

It prevents the build-up of debris in the plumbing system by trapping it and prevents sewer gases from entering the home by draining away from the sink. In exposed plumbing, P-traps tend to be made of steel since it looks more attractive. However, they can also be made of PVC pipe.

How do you clean a bathtub P trap?

  1. Mix 1/2 cup of baking soda with 1/2 cup of water, then pour the mixture down the shower drain.
  2. Douse the shower drain with half a cup of vinegar immediately after pouring baking soda in.
  3. Let the baking soda and vinegar sit in the P-trap for 30 to 60 minutes with a stopper or plate covering the drain hole.

Where is the trap on a bathtub drain?

The bathtub trap is attached to the drain outlet by a fitting that is screwed to the end of the tub drain assembly. Another end of the tub drain assembly is glued into a horizontal pipe. The pipe is connected to the waste stack, which empties into a septic tank.

 What is a bath trap?

Bath traps

Under bathtubs, beneath the slab, there is a device known as a “bath trap.” So why do we leave such a large hole under a bathtub? Plumbing contractors typically leave these openings for their convenience when moving or servicing the plumbing.

 P traps: how do you empty them?

How to Unclog a Sink’s P-Trap

  1. A plastic bucket should be placed directly beneath the P-trap.
  2. Remove the coupling nuts that attach the trap to the sink tailpiece and the adjacent wall fitting with pliers.
  3. Make sure the trap’s interior is clean by using a straightened wire coat hanger or a large nylon bottle brush.

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