Home Plumbing Explained

Everything we do relies on plumbing. When you think of it for a second, whether it’s washing your car or brushing your teeth before going to bed, you’re using your home’s plumbing system. This is why it’s so important to keep your plumbing in tip-top shape. It can be a very complex system, but it generally consists of four things: waste drains, waste vents, potable water and rainwater management. So let’s go through each process one by one and talk about what they do.

Let’s start off with the drains. Most homes have either ABSs, PVC or cast iron drainpipes and vents. These pipes are connected to all the fixtures in the home, such as toilets, sinks, bathrooms and showers. When the fixture is used, the waste is carried to inside these drainpipes that have a slight slope to them down the main drain up until it reaches the municipal drain under the street.

These are what give you access to the inside of the pipes in case there’s a blockage. Most homes in the US also have these outside, so it’s easier for the plumber to access it. As for pipe sizes, most toilet drains are three inches. Kitchen and bathroom sinks are inch and a half or two inch. If it’s wet vented and showers and bathtubs are two inches by code, the main stacks are either three inches or four inches, depending on what the code asks for and your municipality.

But some homes don’t have municipal services, so how do they get rid of their waste?


The main drain pipe that would normally go to the sewers goes into what’s called a septic tank. This septic tank, which is either concrete or polyethylene, separates the solids from the liquids and flows into a Leitchfield or drain field, which then goes into the ground to get naturally filtered. The solids, though, eventually need to get pumped out by a vacuum truck to make sure it functions properly. Now onto the venting for these fixtures and drains to function adequately, the system needs to be properly vented.

When a toilet is flushed, for example, the water pushes the air downstream, causing a negative pressure behind it. The vents are what equalize this change in pressure to prevent things like gurgling and Petrovs being siphoned out, which would allow for sewer gases to find their way inside your home. These vents get their air through the roof and need to stay clear from bird nests and debris or you’re assured of having problems. Something else this vent serves is to relieve any pressure buildup inside the actual municipal sewer line.

Some cities had their manhole covers blast up 50 feet in the air because rats would chew on electrical wires and would in turn create a spark and ignite the methane gas inside the sewers. So the vent minimizes the chance of this happening.

As far as potable water goes, it comes from the street like the other services, and typically has between 40 psi of pressure. Every home with a water supply from the city has to have a shut off valve outside just like this in case the city needs to close the water. This copper line, which is normally three quarters of an inch in size, comes into the basement through the concrete slab to another shutoff valve, which is only accessible to the homeowner.

Here we see the hot water tank, your hot water tank, which is either electric or gas fed, is fed cold water to then heat it up and distributed throughout the house. Thanks to the city’s pressure, some homes still have PVC or copper lines, but new constructions use mostly PEX as it’s reliable and quick to install. So back to be first question, how does one get water if there’s no municipal services in rural areas?

People use wells.

A well is basically a hole that’s drilled approximately 500 feet in the ground to access groundwater via pumping. This water is pumped back up and goes through a series of apparatuses to make the water drinkable. A downside to this is if the electricity cuts out, you’ll need a generator to get a glass of water. And the last aspect is rainwater management.

In the past, rainwater and sewage was combined, meaning the rainwater went into the same sewer as the waste from your house. Since then, they’ve been separated. To make water management easier, so when it rains, all of this water has to go somewhere, right? The rain that falls on the house’s roof trickles into the gutters.

Now, the gutter’s job is to divert the water away from the house to prevent water infiltrations. So what most people do is install a five foot piece onto the downspout so the water has somewhere to go, which is perfectly fine. Other people prefer recovering this water in barrels to use as non potable water to water their plants and flowers. And some actually connect them to the weeping tile or French drain. The French drain is the corrugated pipe that runs around the house is footing to catch any excess water in the ground.

The problem when doing this is that the municipal drain could get overloaded very quickly and overflow and it is up to you to plumb a drain on your own. So it’s best invest in a rainwater collection system or to just let the soil absorb the water if possible. So where does all of this waste and rainwater go once it’s in the municipalities? Hence both of these services head down the road, which eventually need to be lifted at a lifting station which pumps the storm and wastewater back up so they don’t go too deep.

The rainwater dumps itself into a nearby river and the waste continues to the sewage treatment plant, where it passed through multiple filters and treatment stages to then be released back into the nearest river. And the cycle continues. The water from the river is filtered and pumped back into the city’s main as potable water, which is safe to drink.

And that’s basically how your plumbing system works. I hope this clarifies some things about how we use our water, and I believe it’s important we all know how it works, as without it, we wouldn’t have the same life quality as we have. If you need professional help with your plumbing system, contact Palm Desert Plumbers now and we’ll help you out.