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No P Trap in Shower Drain: All You Need to Know About It

Installing a new shower can be a very exciting time. But, what happens when you notice there is no p trap in the shower drain? Don’t let this problem set you back. For every plumbing problem I’ve encountered, I always found plenty of helpful resources.

If there is no p trap in the shower drain, there are several alternatives you can consider including the waterless trap and other devices such as a trap guard and a bottle trap. You can also opt for installing a p trap even after you have finished shower construction.

Let’s explore what you can do if there is no p trap when you inspect the shower drain.

No P Trap in Shower Drain

What is a P Trap?

Plumbing has come a long way in the last few centuries. The p trap was invented by Alexander Cummings ( in 1775. It was originally called an s-bend and later became a p trap because of its shape.

A p trap is simply a u-shaped bend in the pipe that links a drain to a septic tank or sewer system. P traps are installed in showers, sinks, and tubs. It is a device that holds water to ensure that the pipe has an airtight seal.

The design prevents gas from sewage to back up into your home. In addition, the p trap allows you to recover small items that fall into the drain.

How Does a P Trap Work?

As you are troubleshooting your shower, it is helpful to know the basic mechanism of a p trap. The p trap holds a small amount of water to create an airtight seal from your shower drain to the sewage pipe.

If it is functioning properly, will push old water through it down to the sewer pipe. The small bend in its design traps water to create an airtight seal. When water drains, air flows from an outside vent to equalize the pressure through the p trap.

What Happens When My Shower Doesn’t Have a P Trap?

If you were to leave your shower without a p trap, you can risk damage. Besides foul sewer odors entering your home, solid waste is not caught leading to clogged pipes. It is absolute bliss stepping into a shower and enjoying a clean and refreshing experience. You certainly wouldn’t want to deal with foul odors or backup water.

Other concerns include:

Insects are attracted by foul odors that emanate from your shower drain (see our guide on the tiny bugs you might find in the bathroom). Cockroaches and flies are attracted by sewage gases. Mosquitoes can also become a problem as they thrive in the moist conditions of your bathroom.

Health issues are also among the concerns of not having a p trap.

 Since sewage gases come from decomposing waste, they are not healthy when inhaled. Short-term exposure to these gases can cause nausea and vomiting. Long-term exposure can lead to serious health issues such as seizures, pink eye, loss of smell, coma, and death.

The most dangerous gas that can enter your shower drain is carbon monoxide. The Centers for Disease Control and Prevention ( state that symptoms of carbon monoxide poisoning are dangerous and sometimes lethal. Symptoms include dizziness, headaches, vomiting, and confusion. Prolonged exposure can be deadly and hard to detect.

Code enforcement in your city, state, or country can be a problem. If you violate your local regulations when building or renovating your shower, you may get fined or have to re-do your project.

The most dangerous gas that can enter your shower drain is carbon monoxide

Alternatives to No P Trap in Shower Drain

When you realize that you don’t have a p trap, there are alternatives to solve the issue.

Alternative #1: HepvO Waterless Valve

If installing a p trap is not an option, you can install a HepvO valve instead. It was invented for the RV industry. This type of valve provides an effective way to seal sewage gases. Its design is perfect for compact spaces such as shower drains.

The HepvO valve is horizontally installed and costs similar to a main water shut-off valve. Some prefer this valve instead of a p trap because it is smaller and easier to work with.

Alternative #2: Bottle Trap

You’ll have to check your regional legislature to see if bottle traps are legal where you live. They are commonly seen in designer sinks because of their sleek design. It is a great device for tiny spaces and takes up less room than p traps.

Bottle traps’ waste water exit travels horizontally. The lower part of the device unscrews for the removal of clogs and debris. They function similarly to p traps and provide an airtight seal to prevent odors.

Some plumbing professionals don’t recommend bottle traps because they are more likely to cause clogging. A clogged drain can create a number of problems.

Alternative #3: Grease Trap

Some people choose grease traps that are compatible with showers in an industrial setting. It is worth mentioning this alternative in case your infrastructure can accommodate such a device.

Grease traps come in a variety of shapes and sizes. You do have to check your local legislature to be sure your installation is legal. This is a controversial alternative because grease traps are made for kitchens and they don’t block foul odors. However, they are still used as an alternative by some.

Alternative #4: The Waterless Trap

The waterless trap is one of the most effective methods for preventing sewage gases from entering your home. These traps have a self-sealing membrane that creates an airtight seal to prevent odors. The membrane allows water to pass and closes immediately to prevent sewage gases from entering the line.

 Grease Trap

Although a waterless trap is a bit more expensive than a p trap, it is much more effective. Since it doesn’t hold water, you don’t have to worry about it evaporating over time.

Alternative #5: TrapGuard

This product was designed to be an alternative to trap primers. They prevent the evaporation of the trap’s water barrier. TrapGuard works by releasing water into the trap. However, some professionals see trap primers and TrapGuard as unnecessary in most cases.

Instead, they suggest using a TrapGuard as an accessory to a p trap. It helps keep the p trap moisturized when you’re away from home for a long time.

No matter which alternative you choose for your home, it is best to call a professional plumber as soon as you notice no p trap in shower drain.

Do ALL Showers Need a P Trap?

Yes! All shower drains need a p trap installation. It is a critical component of your piping system. The p trap acts as a ventilation device that helps you keep the air pressure in your pipes balanced. When air pressure is balanced, it prevents siphoning that happens when there’s negative air pressure.

Certainly, traps are essential in a home’s plumbing system. According to Cornell University’s Legal Information Institute (, U.S. legislation requires all shower drains to have p traps.

How Can I Install a P Trap?

Of course, the best way to install a p trap is before you finish the shower construction. However, you may notice that you’re missing this important component after your construction is complete. Or, perhaps you have an old p trap that needs to be replaced by an upgraded installation. If that’s the case, you can follow these steps:

1. Cut the Subfloor Surrounding the Shower Drain

With the help of an electric saw, you’ll be able to cut the subfloor that surrounds your shower drain. Cut a squared space that measures 12″ x 12″. To be able to nail the subfloor back into place when you’re finished, be sure to cut above the floorboards.

2. Create the Necessary Space Surrounding the Drain

Once you achieve the square cutout, open the floor underneath it with a prybar. To install the p trap, you must cut the drain pipe. Cut it to match the size of the p trap.

Measure the length of the entire p trap. Then, measure the distance from the drain to where the drain pipe was cut. To avoid damaging the drain pipes and the floor, be sure your cut is not too deep.

3. Connect the Drain Pipes to the P Trap

Find the section of the drain pipe that runs horizontally. Connect it to the p trap using a connector and pipe glue. The other end of the p trap must be placed directly underneath the shower drain facing upward.

4. Reinstall Flooring

Now, you can return the square subfloor cutout to its place. Measure the distance between the p trap and the subfloor. Cut a pipe that measures the same length and diameter as the p trap’s end. Finally, reattach the drain cover and shower drain.

Wait for about 60 minutes until the glue is completely dry. You may then use the shower as usual.

P Trap Problem Fixed!

If you find yourself without a p trap on your shower drain, this article is a great start to resolving the issue. Plumbing problems don’t have to be a bother with the right knowledge and tools. Although you may be able to fix the problem yourself, it’s always a good idea to seek the support of a trained professional.

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