Everything You Need To Know About A Household Drainage System

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It’s likely that you only think about your home’s drainage systems when something goes wrong – like when you’ve got clogged drains or a leak in your pipes. But it can be helpful to learn the basics about the different components that make up these plumbing systems.

So in this guide from Wilco Plumbing, we’ll provide you with a basic overview of how home drainage systems work, and what the different components in your drainage system are intended to do. Read on to learn more.

1. Fixture Drains

It all starts with fixture drains. These are attached to each of your plumbing fixtures, like toilets, showers, bathroom sinks, and kitchen sinks. They attach to a drain pipe that carries water out of the fixture and into your drain line. They are an important part of your drain system, since fixture drains are where all of your wastewater will enter your branch drain lines, which lead to the rest of your drainage and sewer system.

2. P-Traps

P-traps are located immediately beneath bathtubs, showers, sinks, and other plumbing fixtures. This part of your drain system consists of a wide pipe with a sharp “P”-shaped bend in it, hence the name.

P-traps hold some standing water, sealing your drainage system. This prevents sewer gases (and smells) from rising out of your drainage system and stinking up the room. Without a P-trap to trap water and seal the system, nasty odours would be commonplace in your home.

3. Toilet Traps

Toilet traps function in the same way as a P-trap. A toilet trap is meant to trap water, preventing noxious gases from the sewage system from rising into the bathroom. However, toilet traps are typically built into the design of the toilet itself, rather than being a separate component.

4. Clothes Washer Stand Pipe

This pipe is located near your washing machine (if you have one). Your washer empties into an upright standpipe, which leads into a curved drain trap that functions similarly to a P-trap or toilet trap, preventing nasty smells. It empties into a branch drain line.

5. Branch Drain Lines

Branch drain lines “branch” off from each individual water-using fixture in your home, like sinks, bathtubs, washing machines, dishwashers, showers, and more. These lines usually run horizontally with a slight downward slope, and connect to the soil stacks of your plumbing system.

6. Soil Stacks

A soil stack, which is also sometimes called a “main drain stack,” is a large-diameter vertical pipe, usually between 6-10 cm in diameter. Soil stacks are located at the end of your branch drain lines, and carry wastewater and solid waste down toward your sewer line and septic tank.

7. Soil Stack Vent (Drain Waste Vent)

You may not realize it, but proper air ventilation is actually essential for your drainage system. Your drains must be vented properly in order to maintain neutral air pressure, and prevent the suction power of water from draining all of your individual drain traps.

That’s where the soil stack vent, also called the “drain waste vent” comes in. This vent consists of a large pipe, which attaches to your drain system at its lowest point, and rises through your home and out of the roof.

Then, gases can be vented harmlessly out of the vent, and air can enter to maintain proper air pressure equilibrium in your drainage system.

8. Sewer Line Clean-Out

The sewer line clean-out is attached directly to your sewer line, and it’s designed to be used for emergencies and for cleaning out your sewer line, as the name implies. It consists of a large cap or hub that is mounted to your sewer line. This can be in your basement or utility area, or may be located outside the foundation of your home.

The cap or hub can be removed from the clean-out to access the interior of the main sewer line. This is usually required if there is a large clog in the main drain. A flexible camera can be used to identify the problem, and then a motorized auger can be used to eliminate the clog in your sewer system.

9. Main Sewer Line

Your main sewer line is where all of your soil stacks connect, and is located under the lowest floor in your home. This line runs horizontally at a slightly downward angle, and it runs out to the septic tank or municipal sewer main of your home. You usually will not be able to see this line, as it’s located below your foundation slab.

10. Municipal Sewer Main Or Septic Tank

The final part of your drainage system is the municipal sewage main, which is owned and operated by the city. This is where your main sewer line connects to drain sewage from your home. Or, if you are located in a more rural area, you may have a septic tank, which is where your wastewater will drain. Either way, this is where your home’s drainage system ends.

Need More Information? Having Issues With Your Drainage System? Call Us Today!

At Wilco Plumbing, we’re experts in plumbing and drainage systems in Sydney and the surrounding areas. Having trouble with clogs? Got strange smells in your bathroom? Hearing weird noises from your drains? Our team is here to help. Just give us a ring at 02 9186 3371 or contact us online to schedule an appointment with trusted plumbers in Sydney and get the help you need.