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How to Install New Plumbing in House? A Step-by-Step Guide

The plumbing system is the lifeline of any house as it keeps fresh water flowing into the fixtures and wastewater exiting the system efficiently. This system is installed before setting up the drywalls so that pipes and vents can be laid correctly.

So, how to install new plumbing in house? A step-by-step guide will show you the process from checking local plumbing codes to installing fixtures.

Follow the guide till the end to install plumbing from scratch. Let’s get started.

How to Install New Plumbing In House? A Step-by-Step Guide

A plumbing system has three main components, such as water supply lines, drainage lines and vents, and plumbing fixtures or appliances. We will go over the steps of installing these components in detail.

How to Install Water Supply Lines?

Before you install plumbing in house, always check local plumbing codes. Then follow the steps below.

Step 1: Create the Plumbing Layout

While this can vary in different states, it is always better to have a pre-designed plumbing system layout. Plan where the water supply lines, drainage lines, and fixtures will sit so that it becomes easy to install the components. Mark the places in white so that they are clearly visible from a distance.

Step 2: Drilling Holes for Pipes

The next step is to drill the necessary holes to install water pipes. Drill through the floor so draw pipes from the main supply line. Make sure the connections are tight, and use clamps to hold the pipes in place.

Water from the main pressurized line enters your house at 50-60 psi. The main supply line is then divided into two lines. One line will go to the appliances directly and supply cold water to the fixtures. The other line will reach the water heater to deliver hot water to the fixtures.

Step 3: Rough Stubbing for Fixtures

Rough stubbing refers to creating ends where the appliances can be fitted to test the plumbing system. Install copper fittings at the end and check for any leakage in the system. Let it sit until you install the drywall and place the fixtures.

How to Install Drainage Lines and Vents?

Drainage lines collect wastewater from all fixtures and carry them to the main sewer line. Here is how you install it.

Step 1: Place the Main Stack Correctly

The main stack will collect wastewater from toilets and other fixtures. It is basically a long pipe with a diameter of four inches. The pipe sits in the basement, and the top end of the pipe will be higher than the roof.

Sewage from toilets will come through the bottom line. Wastewater from other fixtures will come through the middle line. And the top end of the pipe will remain open to work as a vent.

Step 2: Install Large Fixtures

Large fixtures like toilets, showers, or bathtubs can be hard to install after the drywall is installed. So, you should install them first. Make sure these fixtures are installed where they should be exactly after installing the drywall. Be precise about measurements while installing these fixtures.

Step 3: Install Traps Below All Fixtures

U-shaped pipes are used as traps in the plumbing system so that they can let the sewer gasses out through the vents. Otherwise, those stinky gasses will enter the house and make living there horrible. Install these traps below the sink and shower drains. The traps should be upright so that they can retain the right amount of water.

How to Install Plumbing Fixtures?

Plumbing fixtures or appliances, such as faucets, sinks, etc., should be installed at last when the drywall installation is complete.

Step 1: Pull Rough Stubbings Out

The drywall will have the necessary holes to pull the rough stubbings out. Carefully remove the fitting from the ends and prepare them for finishing valves.

Step 2: Install the Remaining Fixtures

It is time to install smaller fixtures like faucets or sinks. Make sure the fixtures are connected to the stubs tightly. After installing sinks, apply caulks to hold them in place.

How Much Does Plumbing for New Construction Cost?

The cost of installing new plumbing in house can vary depending on your area and the material price. And the cost is calculated per square foot.

According to Forbes, the average cost of installing new plumbing can range from $4.50 to $5.25 per sq. ft. If you hire professionals to install plumbing, labor charges might cost about $60 per hour.


Get answers to frequently asked questions about installing new plumbing in the house.

Q: Which pipe is best for water supply?

A: As water supply lines carry hot and cold water under pressure, copper is the most suitable material for these lines. Copper pipes are also corrosion-resistant, so they will last for a long time.

Q: What size pipe is used in plumbing?

A: The pipe size can vary depending on where you are using it. Main lines might use 1-inch pipes or larger than that. But as the lines are split into smaller sections, pipes with a diameter from half an inch to three-quarter inches are used in plumbing.

Q: Can I install any fixtures into the plumbing system?

A: All fixtures might come with different sizes of inlet ports. So, it is crucial to check the inlet size and match it with the size of the supply line.


Installing new plumbing in the house can be challenging, especially if you are new to this. And local plumbing codes in most areas require at least the supervision of a licensed plumber to install plumbing in your house. But knowing the process would help you a lot.

So, how to install new plumbing in house? A step-by-step guide on installing water supply lines, drainage systems, and plumbing fixtures would help you complete these steps correctly. Plus, it will cost less than hiring an expert professional to install the plumbing.