Does your bathtub need a vent? If you are a homeowner gearing up for a new remodel, new construction, or if you’re just troubleshooting problems with your shower drain, you likely have some questions about your bathroom’s plumbing system. 

Bathtubs should have a vent to help drain wastewater properly. All drains in your bathroom, from your bathtub to your toilet, need a plumbing vent stack.

Without a proper vent, you may hear gurgling pipes, smell a putrid odor, or notice slow-draining water. Not having a bathtub drain vent can even be hazardous to your family’s health. 

While terms like “p-trap” and “vent lines” may not be common knowledge, it’s beneficial for homeowners to know how their drainage system operates. That way, you can identify warning signs and take preventative measures to avoid problems.

It also helps to have some background information to communicate effectively with your plumber or contractor. 

What Is A Bathtub Vent?

After a bath or shower, the residual soapy water needs someplace to go. A bathtub vent is an essential component in a well-functioning drainage system because it helps control air pressure within the drain.

The vent allows fresh air to promote proper water drainage.

Water does not usually flow through the plumbing vent itself. Instead, a bathtub vent is typically a hollow, vertical pipe attached to another drain line that goes to your roof vent.

This allows sewage gases to escape and maintains proper pressure throughout your plumbing system. You can think of it as letting your pipes “breathe.” 

How A Bathtub Drain System Works

Bathtub plumbing is a proficient, simple system that works with gravity. When you unplug your bathwater to let it drain, the water doesn’t go straight down.

Instead, there is a “U” shaped pipe, known as a “p-trap,” to prevent sewer gases from entering your home. Sewer gas is definitely not something you want floating around in your living space; it is composed of toxic gases like ammonia, carbon dioxide, and sulfur dioxide.

Chronic exposure to these fumes can cause sewer gas poisoning, which may lead to eye irritation, respiratory tract complications, dizziness, nausea, headache, and drowsiness. 

Bathtubs have smaller pipes that connect to the main drain pipe in a home. Many tubs feature an overflowing plate to prevent the tub from being filled too high.

These specialized plates have a tiny hole that water will drain into once a certain height is reached. 

There are different kinds of drain stoppers, all with one purpose: to prohibit water from draining out and allow you to have a relaxing bath. Two common types of drain stoppers include a plunger and a pop-up.

When your piping is working as it should, water drains out of your bathtub, replacing the air in the pipes. Have you ever noticed that sound when the tub is almost done draining?

The sound is the water making a vacuum. 

Venting Issues

The entire plumbing system works together for optimal drainage. If you didn’t have a bathtub vent or the vent becomes clogged, you would probably start to notice signs of malfunction. 

If you ever hear gurgling or bubbling sounds in your bathroom, your vent may be clogged. This unmistakable noise is caused by air escaping through the drain. In a working system, the air flows away, thanks to proper ventilation.

When a vent pipe is blocked, the displaced air escapes through your drains and makes a gurgling noise. 

The air from your sewer lines emits a strong, foul, rotten-egg odor. If you ever smell sewage from your drains, your venting system may be obstructed and forcing the air to escape through the drains improperly and not the roof vent.

Over time, this can happen from things like dirt, debris, animal nests, or leaves.

Backed-up water is another tell-tale sign something is wrong. If water is building up at your feet while showering or slowly draining after your bath, there may be hair or an object obstructing the drainage system.

To help keep your drain clear of blockage, be sure to use a bathtub strainer each time you bathe. 

Helpful Bathtub Drain Hacks 

How do you know if your drain just has a minor blockage, or if there’s actually a significant vent issue? If your bathtub isn’t draining properly, you may have an object or build-up causing the blockage.

Even with precautions like bathtub strainers, drains are commonly clogged with materials like hair and soap.

Be proactive and clean your drain at the first sign of backed-up water. You can be preventative and flush your pipes with cleaner on a weekly or monthly basis.

If all else fails, there are some hacks to remedy minor clogs. First, remove the screws on the top of your drain with your handy screwdriver. 

  • Clean it out: You may want some rubber gloves for this. Carefully remove the hair and sludge that may be blocking the water from the tub drain. You may need to detach the strainer. If the clog is too far from reach, use a plumber’s snake. However, be careful as you can damage your pipes using this method. When in doubt, call a plumber.
  • Plunger: Plungers work great in bathtubs. You’ll want to cut the overflow to create a vacuum. Some use duck tape or electrical tape to make an air-tight seal. You’ll also need to remove the drain stopper and add a little water to the tub.
  • Boiling water: Hot water may be the easiest trick to unclog your pipe. The temperature heats the blockage, helping it to dislodge and continue safely down the drain. The hot water might spit back out, so be careful not to burn yourself. 
  • Baking Soda and Vinegar: This is a classic method that is good when boiling water doesn’t work independently. Begin with boiling water down the drain. Then, follow the boiling water with a baking soda and vinegar solution (1cup of baking soda and 1 cup vinegar). Wait for at least 10 minutes, and carefully pour more boiling water into the drain. 
  • Chemical drain cleaners: If nothing else works, you can run to the hardware store and purchase a chemical drain cleaner. These cleaners are usually very effective, as they contain chemicals like potassium hydroxide or sulfuric acid. Be sure to select a product intended for your type of bathtub plumbing, and remember to use it with caution. Many plumbers don’t recommend these cleaners because of the potential damage that they may cause your pipes. 

If none of these methods work, call a plumber. 

Bathtub Parts To Know

Modern plumbing allows us to enjoy a convenient bath or shower to stay clean. Every part of the bathtub has an important function.

Some of the main features include:

  • Tub: The bathtub provides a vessel for water. Many bathtubs have a shower and tub, but they can be separate. Bathtubs are usually shaped like a rectangle, circle, or oval, and a person will sit as they bathe. 
  • Shower: A free-standing shower does not have a tub. They have a hot and cold valve to control water temperature and sometimes have a single combination valve. There are many types of showerheads to choose from. 
  • Water Supply: The water supply allows water into your faucets or showerhead. Warm water comes from your water heater, whereas cold comes from tap water.
  • Shutoff Valve: The main shut-off valve controls water flow to your entire house. Some newer homes have shut-off valves running to certain fixtures. 
  • Faucet Spout: When all of the piping pressure is correct, water flows from the faucet. 
  • Drain: The drain is a circular hole that allows water to leave your bathtub through the drain pipe. Tub drain pipes are usually made of brass, ABS plastic, or PVC.
  • Trap: Bathtubs should have a p-trap pipe. The curved design traps water so toxic sewer gas cannot pass through outside into your living space. 

Sharing Bathroom Vents

Bathroom fixtures often share a vent if they are close together. For example, many toilet drains and faucet drains share a vent.

If you decide to install a vent on every fixture, you may be wasting time and money. However, the size and placement are essential when determining vent sharing.

For example, you can connect fixtures as long as they merge above the flood level of the lowest fixture. The vents should slope upwards to function correctly and lead up to the roof vent.

An air admittance valve can be used when you can’t route a vent to the roof. 

DIY? When To Call A Plumber

Calling a trained, licensed plumber often saves time, money, and hassle. Plumbers have the experience and education to fix your problem or support your home improvement goals.

Plus, they should be aware of building and plumbing codes. Their expertise may save you from costly mistakes!

Still, it’s tempting to DIY. With plumbing materials, chemical drain cleaners, and plumber snakes on the shelves of any hardware store, many people decide to try and fix their plumbing problems themselves.

However, remember that some of these products may harm your pipes and septic system with their harsh ingredients. When a pipe is destroyed with chemicals, it may need to be replaced, which is a costly fix.

In the long run, it may be better for your pipes to leave it to the professionals.