How Does a P-Trap Work? And Why You Can Smell Sewer Gases in the House
A P-trap is an essential plumbing fixture designed to prevent sewage gasses and smells from entering your home. It is a U-shaped pipe that is installed under the sink or other fixtures that are connected to the drain line.
The purpose of the P-trap is to create a water seal in order to block sewer gas from entering the living space. However, if something causes a break in this seal, such as a leak, you will start to smell sewer gas coming from your sink drains, which is no fun at all.
Here we will explain what signs point to a leaky P-trap and how it can be resolved, as well as provide advice on safeguarding against such issues in future.
Leaking Sink P-Trap: Key Takeaways
- A P-trap is a plumbing component that is designed to prevent sewer gasses from entering a home.
- A leaking P-trap can be caused by loose connections, worn or corroded fittings, and improper installation.
- Signs of a leaking P-trap include water leakage around fixtures, gurgling or slow draining, and foul odors from pipes.
- To fix a leaking trap, you can tighten loose connections, replace worn or corroded fittings, clean out clogs or blockages, and check pipes for proper installation.
- To prevent any leak in the future, you should regularly inspect and maintain your P-traps, use high-quality fittings and materials, and call a plumber for installation.
What Can Cause a P-Trap Leak & How to Fix It
Let’s start with the most common and easiest-to-fix issues first.
One of the most common issues is that the slip nuts have come loose due to vibrations, pressure changes in the plumbing system, poor installation, or the natural settling and shifting of the building.
To fix loose connections, you can follow these steps:
- Locate where the leak is coming from: Check all the fittings in the trap and look for any that appear loose or have water leakage around them.
- Tighten the nut: Use a pipe wrench or slip joint pliers to hand tighten the loose coupling nut or slip joint nut. Be careful not to overtighten compression nuts, as this can crack PVC traps, and even a metal trap with enough force.
- Check for leaks: After tightening the fittings, run water through the sink drain and check for any leaks. If the coupling or slip joint nuts are still leaking then the fittings may be worn or corroded.
- Use Teflon tape on pipe threads: If you have a new installation or you have to re-install the fitting, use Teflon tape on the threads of the pipe to make a watertight seal and stop your P-trap leaking.
If you’re still seeing water leaks around the pipes then you’ll need to remove the entire trap to find the root of the problem.
Corroded or Worn Connections or Faulty Parts
Sadly, deterioration is a common problem and requires immediate attention to prevent any more costly damage from occurring.
The most common culprits are:
- Age: Over time, rubber washers, PVC nuts, etc can become worn or corroded. This is particularly true for rubber seals as the rubber hardens over time and becomes brittle.
- Exposure to chemicals: Certain chemicals, such as cleaning products, can damage pipes, nuts, connections, or rubber washers.
- High water pressure: High water pressure can put extra stress on fittings and cause the threads or rubber to wear out more quickly.
Here are some steps you can take to fix worn fittings in your trap:
- Turn off the water supply: Before making any repairs, turn off the water supply to the area you will be working on.
- Remove the trap: Carefully remove the trap from the sink and drain pipe. Be sure to keep track of any parts that are removed, so that they can be properly installed again.
- Replace the old washer, cracked slip nut, etc: If any fittings are worn, they should be replaced. It’s best to check the whole sink trap for other signs of damage before P-trap assembly.
- Re-install the trap: Carefully re-install the trap, making sure to use new fittings and to achieve a proper seal making sure to avoid over-tightening the coupling or slip nut.
- Turn on the water supply and check for leaks: Turn the water supply back on and check for any leaking. If there is a leak, you’ll need to make further adjustments.
While less common, Improper installation can cause a variety of issues, including leaks in the P-trap. Some common mistakes made during installation include:
- The P-trap coupling nut needs to be tightly secured to the sink to ensure a proper seal, failure to do this properly is likely to lead to a leak.
- Using the wrong fittings or improperly sized ones can cause leaks and make it difficult to achieve a proper water seal. If you find this to be the case, you will need to replace the parts with ones of the correct size.
- To ensure that water flows freely and prevent water pooling, the pipe fitting connected to the trap must have a slope. If the horizontal alignment is too steep or not steep enough, it can cause leaks and other issues.
- A failure to allow enough slack in the pipes by cutting them too short can lead to stress on the threads of the nuts and cause the trap to leak.
- Failing to mount a plastic trap properly with brackets to hold the pipe steady can lead to vibrations that will damage the couplings.
If your P-traps have not been installed correctly, then many of the problems can be dealt with by following the instructions in the step-by-step guides above.
Signs That You Have a Leaking P-Trap
If you notice water leakage around the base of your bathroom sinks, shower, or toilet, it may be a sign that your P-trap is leaking. This can happen if the trap is not properly sealed or if the water seal has been compromised.
Gurgling or Slow Draining in Fixtures
Gurgling sounds or slow drainage in your sink, shower drain, or toilet, may be a sign that your trap is clogged or blocked. This can cause water to back up and overflow out of the sink trap, or lead to a leak.
Foul Odors From Pipes
Stinky rotten egg smells coming from your pipes are a sign that you have a dry P-trap. A dry trap can be caused by a leak or evaporation, and in both cases, sewer gases will be able to travel up pipes and into your home. Odors are annoying but, in truth, the least of your worries – without adequate ventilation, flammable gases can build up and pose a serious health hazard.
If you don’t find an issue with the trap itself, then your plumbing systems ventilation pipes may be the issue.
How You Can Prevent Leaks in Future
Preventing a leak in your P-trap in the future can be achieved by taking the following steps:
- Identify potential issues before they become major problems by regularly checking your plumbing system.
- Buy high-quality fittings and materials from your local hardware store as they are less likely to wear out or corrode.
- If you’re not confident in your own abilities, hire a professional plumber to ensure your P-traps are correctly installed.
- Avoid pouring harsh chemical drain cleaners into your pipes, as they cause damage to the pipes and the fittings.
- Avoid pouring grease or oil down your drains as these can harden and clog pipes, leading to blockages and leaks.
- Don’t put food waste down the kitchen sink – use the garbage disposal fixture or put it into the trash can.
As they say, prevention is better than cure.
A leak in your P-trap can be annoying, if not a dangerous problem to deal with. However, understanding the cause of a leak, how to identify the source, and the steps you can take to prevent further leaks from occurring can help prevent major plumbing issues.
We hope you easily solve your leaky trap and if you have any comments or questions please leave them for us in the box below.