What Size Pipe Should I Use For House Plumbing?

Homeowners that are looking to become more familiar with the plumbing needs of their home will often wonder what size pipe to use for plumbing in the house. This can be a relatively complex question, which can have a variety of answers depending on the situation. In some cases, the answer can be different depending on where in the room you may be standing. This may sound intimidating, but that’s understandable, as professional plumbers train and apprentice for years to become familiar with all of the plumbing sizes in a home. 

We’re going to look at what size pipe to use for plumbing a house, as well as what size the main line is that goes into the home from the municipal source. We’ll look at factors that can affect the sizing that you may want to use, as well as where you can turn for trusted plumbing help in the area. 

What Size Is The Main Water Line In A House?

This question doesn’t really have a single answer. Instead, the answer depends on where in the house you are and what the plumbing will be used for.

In most cases, a home will have a main water supply line size of either ¾” or 1”. This may not sound like much, but with municipal water pressure there is a significant amount of water that can come from a 1” main supply. Once the supply enters the home, it is generally reduced to ¾” for household supply piping. 

This ¾” pipe is what is used to transport water to each room of the home, acting as branches of the main supply trunk coming into the home. From these ¾” supply lines come ⅜” or even ½” supply lines that are routed to each appliance or faucet. 

It’s important to remember that as your elevation increases your pressure decreases, which can have a serious effect on those with already limited water pressure. In most cases, water pressure goes down by 0.5 lb/sq. In. for each foot that a pipe rises above your supply.

What Type Of Pipe Should I Use?


Copper is often used for the main supply lines that come in from the street, and for the main supply lines that run through the home to feed the components. Rigid copper must be cut with either a hacksaw or a wheel-style pipe cutter.


PEX pipe is highly convenient and affordable, making it very popular for many applications. It can handle significant pressure but remains flexible enough to be routed through walls and floors. This also means it needs to be supported, and that any leaks are handled immediately. The red and blue coloring makes telling hot and cold supplies simple.


PVC is one of the cheaper pipes, and while it can’t take much pressure, it is ideal for drain lines. Common locations for PVC piping are underneath sinks. The pipes and joints are cemented together, and it is a rigid plastic pipe so it must be supported over a distance. PVC is vulnerable to heat and UV.


ABS is a plastic pipe like PVC but is heavier-duty and black in color. It is generally used for drains, waste, and vent mains in the home. 

Call Emory For All Your Plumbing & Pipefitting Needs

No matter how simple or complex your plumbing project is, Emory is ready to help take the stress out of it, and get it done quickly and professionally. If you need additional supply lines for an addition or a remodel, reach out today and discuss your project and your needs with one of our local experts.