How home plumbing works

As a homeowner, it is important that you understand the fundamentals of your home plumbing system. These include basic terminology so you can communicate any issues that may occur, main features in home plumbing systems, different types of supply and drainage systems in home plumbing and common issues homeowners experience with their plumbing system.

What is a home plumbing system?

A home planning system is the network of water and gas supply and drainage pipes that run in and out of your home.

It is one of the largest systems in a home, making it the most costly if repairs or installations are required.

Plumbing terminology

Due to a home plumbing system’s complexity, there are several terms that homeowners should familiarize themselves with in case of an emergency. Some terms listed below are common and others aren’t but all are useful to know.

Branch Drain – a drain that leads to the maine drain pipeline 

Fitting – term to describe any part that connects two sections of pipe

Gray water – water waste from non-toilet fixtures

Potable – water that is safe for consumption

Riser – vertical supply pipes that transport water from the brand to a fixture or higher floor

Sediment – debris the sinks to the bottom of water tanks

Soil pipe – pipe that transports waste from toilets

Trap seal – water in a trap that performs as a liquid seal

Water hammer – a loud banging sound that results from a sudden water supply cut off from a fixture, this causes a hydraulic shock 

Aerator – insert that is screwed onto faucet nozzle to reduce splashing by mixing 

Ball Check Valve – valve that uses a ball that can seal against a seat to stop the flow in one direction 

Closet bend – curved fitting under a the toilet to connect it to the drain

Closet or floor flange – ring used to anchor a toilet and connects to the closet bend 

Flow control valve – device that reduces the water flow to a plumbing fixture; can reduce costs and improve efficiency

Main – main pipeline in a supply or drain system where all branches connect

O-Ring – round rubber washed used to make valve stems watertight

Shutoff Valve – valve under toilet or sink to cut off water for repairs

Tee – T-shipped fitting to connect three pipes

Vent – sloped or vertical part of a drainpipe that allows sewer gases to escape and be replaced by outdoor air pressure so pressure is not lost during venting 

For a full list of terms and features, visit Plumbing Terminology 101 by Home Reference. 

How does the home plumbing system work?

There are two main plumbing systems in a home: domestic water system and sanitary waste system. One system supplies clean water while the other removes dirty water.

Domestic Water System

This is where fresh, potable water is supplied from the main city water supply line or well system and it is supplied through the largest pipe in your home’s plumbing system. This water can be used for cooking and bathing. Pressure and flow of the water supply is created using large pumps. Water pressure is not controlled inside your home, instead the pressure is done by the supplier. Depending on the region you live in, your main water supply can come from a lake, well or city water tower. In all cases the built-in pumps should provide enough pressure to your home’s plumbing system.

The water is cold when it enters the system but then divides into 2 subsystems, hot and cold.

Cold Water Supply
Cold water goes directly to the fixtures throughout the structure but branches off to piping that will be channelled to the water heater. The pipes that pump cold water into your home typically run through a central column that goes from floor to floor. Keeping your cold water pipelines together assures that there is a smooth and continuous flow.
Hot Water Supply
Pipes that supply hot water into your home should be shorter than cold water supply pipes. If a pipe is too long, heat can be lost during the transfer from the water heater to the fixture (sink, shower, bath etc). When you turn your faucet or shower on hot water, if the pipes are too long it can take awhile for the desired temperature water to reach you. Lots of water will be wasted during this time and this is another reason why shorter pipes are used for hot water.

Sanitary Waste System

The sanitary waste system in a home plumbing system uses gravity to remove waste from the structure. The process or system within this system is called the “DWV System”.

he waste water network within this system is divided into 2 piping systems, one that takes the water away and the other are venting pipes that stop sewer gas from entering your home. Gravity pushes down the waste into the city’s main sewer system. 

Vents are important in a DWV system because it allows air into and out of your home’s plumbing system. In front of the waste in the sanitary waste system piping where air is being pushed in the direction of the fall which prevents the sewer gas from entering. Positive air pressure will move anywhere it can to get out of the way of waste. When this air pressure is pushed back through the system, it will blow the water seal in the P-trap which allows sewer gas to enter the room which is why venting is important to avoid this from happening. 

The sewer gas exits through the roof of your home and the speed at which it exits is reliant on the size of the pipe; bigger pipes result in faster venting while smaller pipes result in slower venting. 

The drain pipes that eliminate dirty water from your home plumbing system get bigger the further they are from a fixture. The change in pipe diameter is to ensure that there are no blockages due to the debris left behind over time. The water that is flushed down with the waste must go at similar speeds and at a specific angle because one without the other can cause more debris to accumulate. When it reaches its final destination which is your city’s sewer system, the diameter of the pipe is at its largest point. 

Common issues that may arise in a home plumbing system

As a homeowner, it’s useful to be aware of any common issues that you could experience in your home plumbing system. This makes it easier to identify the cause of the issue so you can explain it correctly to your local plumber.

Slow draining

Slow drainage can result from a clogged drain. Some common reasons why clogged drains occur are due to built-up grease or excessive food waste disposal down the drain. To fix slow draining, use the appropriate plunger for the fixture you’re trying to unclog. 

Bathtubs require a cup plunger and toilets, a flange plunger. Make sure that the fixtures contain water in them in order to successfully unclog it. 

Prevention is the best solution for slow draining and some of the best practices are to install a mesh trap on a shower or tub drain, flushing down the drain with large amounts of water all at once or even schedule a regular drain cleaning with a professional. 

Leaky Faucets and Pipes

Dripping or leaky faucets and pipes are caused when the washer that creates a seal on the tap gets damaged. Sometimes, special tools are required to fix this problem so call a plumber if you don’t feel confident to do it yourself.

Low pressure water

If you are a homeowner of an older home, you are most likely to experience low water pressure issues. As mentioned above, water pressure is not controlled in your home but from your water supply source. A sudden drop in water pressure can be from your main pipeline, in which case your neighbours are most likely experiencing the same issue. If this issue occurs due to a leaky pipe, shut off your home’s water supply for a few hours and after some time, check your water meter. If there is a change in your water meter, it is likely that there is a leak. Contact a plumber for an inspection to locate the main issue.


Having basic understanding of your home plumbing is crucial if you want to be able to identify any issues that may arise in the future. Having the knowledge to figure this out on your own can save you money because some plumbing fixes can be easily done on your own with the right resources but others require professional experience. Locate a local plumber and save their contact information in case of an emergency!

Call Us For All Your Plumbing

Licensed plumbers Toronto residents count on. As a plumbing technicians, we are here to protect your home and business, meanwhile saving your money for the long run.

Plumber Toronto Pro is known for comprehensive plumbing in Greater Toronto Area for both residential and commercial customers. We are always here when you need us with 24-hour availability, 7 days a week.