How much does it cost to install a main water line?

Reviewed by Cristina Miguelez remodeling expert. Written by Fixr.com.

Your main water line is arguably the most important part of your home’s plumbing. It carries fresh water from the city’s supply into your home. It is located underground, where it cannot be seen, and lasts up to 50 years when installed properly. If it fails, you may notice problems like a pressure drop or a higher water bill. Many factors impact the cost of a new water line, including how far the line must travel, pipe diameter, and material. Raw material cost increases and ongoing plumber shortages are projecting increases for “behind the wall” plumbing to continue through 2023 and beyond. Expect costs to rise from 4% to 8.5% over 2023 for any plumbing project, including main line installations.

The national average for replacement ranges from $1,500 to $12,000, with most homeowners paying around $3,750 for replacing a 25-foot long main line with galvanized steel using a trenchless installation. This project’s low cost is $1,125 to replace a 10-foot long main line with PVC pipe using a trenchless installation. The high cost is $22,500 for a 100-foot long main line with copper pipe using a dug trench installation.

Cost to Install Main Water Line

Main Water Line Installation Cost per Foot

The main line for your water is considered a branch line from your town or city’s main line. It extends from the edge of your property to the water meter at your house. It runs under the ground through your yard. This may mean your front, side, or backyard, depending on which is closest to the city line. The area of your yard does not impact the project cost. The cost to replace a main water line in the backyard is the same as the front yard if all other things are equal, including the length, pipe type, and hookup.

Your main water line connects to your plumbing at your home. This can be above ground in some cases. However, if you have a full basement, and this is where most of your home’s piping is located, you may connect the line at the basement. This has the same costs as any other replacement unless you switch locations. If the water mainline changes location, the cost to replace a main water line in the basement may be slightly higher because you must drill a new hole through your foundation.

Because this distance varies by property, costs are generally calculated by the linear foot. Several methods of installation or replacement and different materials and soil impact the cost per foot. Your main water installation ranges from $75 to $225 a foot, with most people paying between $100 and $200 a linear foot. The farther back from the road your home is located, the higher your project costs.

Main Water Line Replacement Cost by Method

The bulk of the costs for this project comes from the installation. While the material you choose for your line impacts the final costs, labor makes up the majority. There are two methods for installing or replacing a main water line from the street to your home. The first is digging and backfilling. A trench is dug in your yard so that the pipes can be accessed, laid, or removed. The second method is trenchless. Only two holes are dug, one near the street and one near your meter. The pipe is threaded through the ground between them. Trenchless installations are less costly and less likely to disturb your property. It is the most common method unless issues prevent this installation type. Below are the average costs for the two types of installing or replacing a main water line.

Trenchless Water Main Replacement

The average cost of a trenchless water main replacement is $75 to $150 a linear foot. This is the most common method of water main installation. It involves boring two holes at either end and tunneling a cable between them. Once the tunnel is in place, the pipe is snaked through. In most instances, the water main installation is trenchless whenever possible. There is no significant change in your landscaping with this method.

Digging and Backfilling a Trench

The cost of digging and backfilling a trench averages $175 to $225 a linear foot. These costs do not include replanting grass, repairs to sidewalks or other areas, or other work. If your line cannot be replaced using the trenchless method, an excavator is brought in to dig the old line. A large trench is dug across your property to uncover the line, which is manually removed and replaced, and the trench is backfilled. This method is typically used for new installations rather than replacements. It is also more likely to be used if the main valve is located beneath a sidewalk or other inaccessible area that requires digging to access.

Cost of a New Main Water Line by Material

The pipe carrying the water to your home can be made of various materials. While cost is one factor to consider, other issues include city regulations, climate, and soil type. Some cities have specific guidelines for the exact pipe and size you can use, while others allow you to choose based on your water needs and soil type. For most single-family homes, your main line may be ¾” up to at most 2” for homes with extremely heavy water needs. In most homes, 1” is the preferred diameter. Your pipe diameter is generally determined by the distance of your home from the water supply and the height difference. A narrow diameter can increase water pressure if your home is above the main supply. Otherwise, a 1” diameter is recommended. Your plumber can determine the correct choice for the project.

The most common pipe materials include PVC, polyethylene, cast iron, fiberglass, brass, and copper. Of these, PVC is the least expensive and not impacted by soil type. It should not be used in hot climates and must be buried below the frost line in a cold climate. Polyethylene is not impacted by heat or cold, so it may be a good alternative, but it can be harder to work with. Cast iron is also not affected by heat, cold, or soil, but it can corrode, so it is not as common, although it was once the standard. Brass and copper are more expensive and corrode in high-pH soil. Fiberglass is durable and good for short runs because it does not come in long sections, so it is best used for homes less than 10’ from the road. Below are the average costs for the different materials.

Labor Cost for a Plumber to Replace a Main Water Line

Labor costs for replacement and new main water lines have similar cost ranges. Costs typically average $70 to $200, with plumbers charging between $75 and $150 an hour for this work.

While the processes of new installation and replacement are slightly different, the time and labor are very similar. In a new installation, the line must be laid, and a new water meter and valve installed on the home. In a replacement, the water meter and valve are usually left alone, so while the old pipe is pulled out before the new one can be installed, both projects take around the same time to complete, resulting in similar costs. There can be variations, such as if an old line is difficult to remove because it is tangled with tree roots, increasing costs. Your costs could be higher if you need to replace the water meter. However, costs fall very close to both projects in most cases.

Cost of Moving a Main Water Pipe

Moving the pipe has a fairly wide cost range of $100 to $250 a linear foot. The old pipe is disconnected and removed. If it can be reused, it is, but people often use a new line. After this, the installation in the new area looks similar to a new line installation. The difference is you likely need to dig up the sidewalk to change the new line location. This has higher-than-average labor costs than a new installation or replacement. You are also responsible for the sidewalk repairs when the job is complete.

Cost to Replace a Main Water Shut-Off Valve

Costs to replace the main water shut-off valve average $200 to $1,000. Your main water shut-off valve is located where the water enters your home. It shuts off the water to your home at once. Replacement costs vary depending on age, how accessible it is, and what material the valve and pipes are made from. You do not need to replace the valve when you replace the line unless the materials are incompatible. For example, if you replace a cast iron pipe with a PVC pipe, your valve may no longer fit on the new pipe, so you need to replace it. Also, the valve’s size must change if you upgrade your pipe’s size, increasing the project cost.

Signs You Need a New Water Main

You may see several signs that your water main needs to be repaired or replaced. The first is a water bill that rises without additional usage. The second is grass that looks particularly green and healthy over the area of the yard where the main is located. This is due to the water leaking into the soil in the area.

If the issue worsens, you should notice a drop in water pressure. This is because more water is leaking out than is getting into your main plumbing. When the pipe fails, your lawn or landscaping above the pipe will be very saturated with water. You may notice puddles or depressions filled with water.

Enhancement and Improvement Costs​

Cleanup

After installation, you may have mud or dirt in the new line. In this case, it can be flushed so that it does not travel through your home. This costs $50 to $100. This may not be necessary, and you can run water at different sources within the home to flush the line instead. Flushing it is faster and easier and means you do not need to clean mud or dirt from your sinks, tubs, and other areas later.

New Water Pressure Regulator

Your pressure regulator keeps pressure even throughout your home. It may need to be replaced when your water line is repaired or replaced but not always. If you have noticed that the water pressure in your home is not even, with one bathroom getting better pressure than another, a regulator can help. Adding it during the main water line installation or replacement can keep total costs down. However, replacing the water line may fix this issue, so speak to your plumber. A new regulator costs between $250 and $400 installed.

Tap Replacement

The connection to the city’s main water line where it branches to your home is called the tap. If your water line is very old, you need to replace the tap when you replace the line. This is likely because old lines and taps use materials like cast iron that may be corroding. If you have problems with the line, the tap may develop similar issues. Replacing it prevents future problems and ensures compatibility between the lines. Costs range from $300 to $500 for this job.

Additional Considerations and Costs

• Depth. Your water main line is located at least 1’ beneath the soil, but depending on the soil, climate, and how far down the supply line is buried, it may need to be 2’ or 3’ under. This is not usually a cost factor with trenchless digging, but digging a trench to lay the line causes costs to add up quickly for each foot you need to dig.
• Permits. You need a permit and city approval before installing a new water main. Permits add costs to your project and cost $50 to $400 for a plumbing permit. Speak to your plumber about which permits you need.
• Roots. Sometimes, your water main line may fail because roots spread into the area, attracted by the water. The roots can cause the pipe to burst, so you may need to remove bushes or trees when replacing the pipe.
• Repair. Your water main line can sometimes be repaired rather than replaced. This costs between $500 and $2,000 and may save you money, particularly on very long lines.
• Access. The harder it is for your plumber to reach the pipe, the higher your costs. If there are trees, stones, and landscaping, you can have a higher total cost.
• Insurance coverage. Your regular home insurance does not usually cover the main water line. For coverage, you need “service line coverage” added to your policy. This covers the main water line and sewer and septic lines, helping if you need repairs or replacements on these lines. Speak to your insurance adjuster for more information.