The Best Pipes to Use for an Underground Water Line (2023)

The Best Pipes to Use for an Underground Water Line (1)

Many people usually overlook their underground plumbing system only to incur high costs in repairing leakages, bursts, and other related issues. Though the quality of plumbing work in terms of installation is paramount in avoiding these challenges in the future, the quality and types of underground pipes used is also important. According to Tru Bore Pipes, in addition to avoiding these high costs of repairs having effective underground pipes is important because it ensures safety for your family or clients. When underground pipes are leaking, you can have your drinking water contaminated, which is hazardous. Some pipes drain dangerous chemicals and waste which you would not want to mix with your drinking water. In this era of environmental sustainability, you should avoid contamination of water, soil, or air through the odor that low-quality underground pipes may emit.

HDPE Pipes

They are high-density polyethylene made of thermoplastic material, a product of monomer ethylene. They are among the pipes you should think about for your underground water line needs. The pipes contain non-toxic materials, which do not contaminate water, and hence ideal when piping for drinking water. The pipes are tasteless, meaning they don’t affect the quality of your water as the water does not take any taste from the pipe. They are also environmentally friendly as they don’t emit carbon into the environment hence important for green construction. According to Uooz, these pipes are made of high quality; therefore, they don’t easily burst and are non-corrosive. They are easy to install, and flexible thus, they can be easily manipulated to fit your needs. In case of damage, the damaged part can be removed and replaced by heating both ends until they are molten and then joining them to form a strong bond. This means you don’t have to replace the entire piping system hence reducing the replacement cost. The pipes are long-lasting and can last up to seventy years.

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PEX Pipes

PEX is an abbreviation for Cross-linked polyethylene. The pipes consist of polymers linked together by a sequence of short bonds. They are manufactured by melting high-density polyethylene polymers giving them relatively much flexibility compared to the others. They are also highly used for underground water lines. Due to being more flexible, they are applicable for your house backyard, where you need to avoid obstructions when laying your underground lining. They are also cheap and easy to install as you don’t require fittings such as coupling and elbows. Therefore, though they may not be long-lasting as HDPE, which can remain in a good state for about thirty to fifty years, you may still choose them for your underground line water. According to The Kikoo Web Radio, PEX pipes are more flexible, resistant to chemical corrosion, and can withstand high temperature and elements such as pressure.

Copper Pipes

Copper pipes are also considered reliable pipes for your underground water line. They are known for their high resistance to leaks, bursting, and corrosion. Copper material can remain in the ground many days without changing color or being affected by rust unless for soil condition that the pipe has been covered with has low pH levels or high concentrations of sulfur. According to PVC Fittings Online, some of the reasons why people have avoided copper is due to inflexibility, making it require other fittings like elbows. It is also very expensive, making customers prefer to buy other types of pipes. However, if you are looking for a durable underground water line, this is the pipe to go for. Though costly its worthy the price. It is tough, durable, and can withstand cold weather, especially during winter. This means even with freezing conditions, unlike PVC, it does not burst, becoming ideal, especially if your region experiences winter.

PVC Pipes

Polyvinyl chloride, commonly known as PVC, is one of the pipes most people prefer to use for underground water lines. It is a thermoplastic material that ranks among the top three highest manufactured polymerized materials. It is preferred due to its strength, ability to withstand corrosion and rust and a pocket-friendly budget. It is a common pipe choice for a lot of home projects. PVC is cheap and resistant to deterioration and rusting. “According to Neit” (, PVC can operate under extreme water pressure, thus very useful for your main underground water delivery line. The other advantage is being light which makes it easy to install, and having a smooth inner coating that does not trap sediments. Therefore, with PVC pipes, there will be no need for you to look for professional plumbers to unblock your water system. The maintenance cost for these pipes is therefore also low. However, PVC pipes also have a setback; they are not flexible. Therefore, they require many plumbing fittings such as elbows, couplings, and adapters. If there are no regulations in your area prohibiting PVCs, then it is a preferable choice as the benefit outweighs the setbacks.

(Video) How to Protect PEX Underground

CPVC Pipes

Chlorinated polyvinyl chloride, commonly abbreviated as CPVC, is subjected to chlorination to enhance performance. Therefore the difference between PVC and CPVC is that the latter is a higher performer. In this case, CPVC is flexible, unlike PVC, meaning you may end up using less or no plumbing fittings depending on the topography of your underground water line, which implies low installation costs. Secondly, CPVC can handle higher water pressure as well as operate under extreme water temperatures when compared to PVC. Whereas PVC can only handle temperatures of up to 60°C CPVC will endure temperatures of up to 93°C. This, therefore, makes them ideal for both hot and cold water when looking for the best pipes for an underground water line. However, CPVC withstands greater temperatures and pressures than standard PVC. Therefore, manufacturers rate CPVC suitable for use in both hot and cold water systems. It is still important, like in the case of the PVCs, to seek if there are regulations in your area guiding its application.

Cast Iron Pipes

Throughout this discussion, we have established that durability is one of the major factors to consider for your underground water line. If this is not taken care of, you will likely incur future expenses when installing pipes afresh or repairing. This aspect may make you to consider cast iron pipe when selecting an underground water line. Cast iron pipes are strong and can resist corrosion which makes them to last longer. These pipes are manufactured from the basic form of iron, which means iron in its impure and unpolished state. It is this iron that is processed to make cast that is then used to manufacture the pipes. They are therefore very durable and can last up to a hundred years. To enhance the hydraulic properties of these pipes and to keep them from corrosion, they are immersed in a compound containing bitumen. This makes them, therefore, very ideal for areas that experience harsh weather conditions, including flooding.

Galvanized Iron Pipe

Galvanized Iron pipe, commonly known as G.I, is also one of the best water pipes for your underground water line. The pipe is manufactured from mild steel, which is carbon steel with low levels of carbon. This means if the quantity of carbon was increased you would end up with cast which is used for making cast iron pipe. Mild steel is therefore preferred in this case due to flexibility and the ability to weld or thread it easily. When the pipe has been prepared it is immersed in Zinc solution. According to Clean 4 Happy, the process of immersing steel or iron in a zinc solution is known as galvanization, and it ensures that the pipe is protected from rusting or corroding. It is this element of G.I that allows its application in the underground water lines. However, this low carbon level lasts for about ten years, but it is a better alternative to copper pipes as it is less expensive.

(Video) What’s The Best PVC Pipe for Underground Usage?

Brass Pipes

You could also consider brass pipe as a good pipe for your underground water line. Brass is an amalgam of copper and Zinc, making it more malleable than metal. It is very flexible, and also has a low melting point. Though not very good for major piping work as it is very heavy, it is ideal for minor water lines installation. The main advantage of brass pipe is that as an alloy, brass is highly resistant to corrosion. The other thing is that due to its low melting point, it can withstand heat effects. Probably the most important aspect that may make you to consider brass pipes is that they are galvanized against corrosion from salty water. This means that your water is also free from contamination. Brass resists corrosion and pressure. Some people choose not to go for these pipes because they are heavy but you can still go for them because they are affordable and because of the other benefits that they come with.

Acrylonitrile Butadiene Styrene Pipes (ABS)

The Acrylonitrile Butadiene Styrene Pipes, abbreviated as ABS Pipes, are made of a polymer material that is impervious resin and amorphous. This type of pipe is strong and durable but not flexible. Its strength and durability makes it ideal when installing heavy drainage systems such as sewerage, stormwater, and drain-waste-vent. ABS is popular because of its high resistance to chemical corrosion. You can therefore opt to go for this pipe as it ensures there is no contamination with normal water lines.

Unplasticized polyvinyl chloride Pipes (uPVC)

Unplasticized polyvinyl chloride pipes, abbreviated as uPVC, are PVC pipes that have no plasticizers. Therefore, they are stronger as compared to PVC hence applicable for large-scale installations. The main advantage of using uPVC pipes is that they are resistant to chemical erosion, can withstand high temperatures, and have smoother inner coating like PVC. This ensures that sediments that can cause blockage are not trapped. Therefore for a commercial underground water line, this would be the most appropriate as they are long-lasting, cheaper and easy to install.

(Video) PEX Pipe From Meter To House

Polypropylene Pipes

Polypropylene pipes are pipes made of many polymer resins by combining propylene monomers. The pipes are therefore very flexible allowing easy bending. This makes them very useful, especially where the underground water line is passing through many obstacles. They are also highly resistant to chemical corrosion, making them very good for acidic and alkaline conditions. They are popular for their durability and usefulness, especially for green construction. Like CPVC, they are also used for hot and cold water or liquid line. However, if you consider using this pipe, their installation is a little bit complex in that it requires highly skilled manpower with specialized tools.

Stainless steel

In terms of durability and non-corrosiveness stainless pipes is your take. This is because stainless steel is an alloy of iron and chromium, ensuring the iron is not affected by rusts and can resist heat. This makes stainless pipes more ideal for the underground water lines that deliver clean drinking water. You may consider choosing this type of pipe if your area is susceptible to corrosion, such as coastlands. The only setback for stainless steel pipes is that they are very expensive even compared to copper pipes which are considered expensive.

Fiberglass reinforced plastic pipe

Fiberglass reinforced plastic pipes, referred to as FRP pipes, are made of fortified layers of fabric with thermoplastic polymer. This makes these pipes very strong structure-wise, while the aspect of resins makes them corrosion-free. They are also heat-resistant as well as have pressure withstanding capabilities. This makes them very good, especially for commercial underground water lines. If your water usage is, therefore, high, you may think of this type of pipe. When considering the best underground water line, the factors to consider among the many are your needs, durability, budget, and the regulations governing the use of different pipes in your area. However, since underground piping is not a daily routine, you may consider going for the most durable pipes even if they cost more.

(Video) How to Choose Water Supply Piping | This Old House


What is the best pipe to run underground? ›

High-Density Polyethylene (HDPE, often just "PE") has become one of the most popular choices for underground service lines, thanks to its corrosion-resistance, durability, and competitive price. Some codes require that buried plastic lines under 2" in diameter be PE (rather than PVC).

Is PEX or PVC better for underground? ›

Plus, PVC can also stand up better to tree roots than PEX or other piping. Unfortunately, the rigidity of PVC makes it less reliable against freezing compared to PEX pipe. This reason is why PEX is a preferred choice for underground piping.

Which pipe is best for outdoor water line? ›

Polyethylene pipes are used in a wide range of pipes for drainage, irrigation, water service and even some varieties for underground gas transport. It is durable and provides long-term resistance to environmental conditions in outdoor and underground uses.

What PEX is best for underground? ›

PEX-B is the first choice for burying due to its higher bursting pressure and reduced issues with leached chemicals. Some individuals are wary of using any type of PEX tubing outdoors because it degrades under UV light.

How deep should a water line be buried? ›

Burying Water Supply Line Pipes

The actual location of your underground pipes should be 12 inches below the frost line. This level may be more specifically defined by your local building codes or even by a homeowners' association, which might dictate the location of water lines in your neighborhood.

Is PEX pipe good for underground? ›

Can pex pipes be used underground? - The answer is YES - It can be used underground. It should be buried below the frost line and best if bedded in sand or stone dust.

How deep should PEX be buried? ›

Underground. Normally, you would bury your underground insulated PEX pipe 2 feet deep (24 inches). This is the right depth for burial for most ground types. Just be diligent enough to backfill it with soil that is not rocky or preferably sand.

Do rats eat PEX pipe? ›

The Problem With Pex Tubing

Mice and rats will chew through anything they can, including plastic, so PEX tubing is at just as much risk as the plastic-coated wiring in a car or an HVAC unit. While all rodent damage can be expensive, if rodents chew through a home's PEX water pipes, the result can be disastrous.

Where is PEX not allowed? ›

You can't install PEX in high heat areas like near recessed lighting. This also means you can't connect PEX directly to a hot water heater, but you can use a connecting material to do this. PEX is semi-permeable, which means liquid can enter the pipe.

Will PEX water line freeze and burst? ›

The truth is, as with any piping, PEX is still vulnerable to freezing if the temperature drops low enough. But thanks to its flexible material, the plastic expands under the pressure of the freeze, significantly reducing the chance of bursting. That means your house is unlikely to flood due to a burst PEX pipe.

What size should main water line be? ›

The most common pipe diameter for water mains is 6 to 16 inches, with 8, 10, and 12 inches also being used. Branch lines providing service to individual homes, offices, buildings, and businesses vary in size from as small as half an inch in diameter up to 6 inches.

Is PEX A or B better? ›

Flexibility - PEX-A is the most flexible, allowing for it to be fastened by cold expansion, which allows the end to be fluted prior to inserting the fitting. PEX B is not expandable and you should never expand the end of a PEX-B pipe. Kink-Resistance - PEX-A has the greatest resistance, PEX-B the lowest.

Can SharkBite PEX be used underground? ›

The answer is yes. All SharkBite fittings are tested and approved for underground use.

How long does PEX piping last? ›

PEX: Due to its flexibility and durability, PEX piping should last at least 50 years. PVC / CPVC: Under typical conditions, these pipes should last up to 100 years. Keep in mind that PVC pipes are often used for drainage because extreme heat can damage them.

Which is better PEX clamp or crimp? ›

Pinch Clamp Tools Work Better in Tight Spaces

Especially when your PEX is pressed up against a wall—or there is just otherwise very little wiggle room to work—crimp tools can become a much bigger hassle. The larger jaw of the tool means you need ample room behind your PEX to be able to make a proper connection.

Do you need to insulate underground water pipes? ›

Insulation is important for underground water pipes because it protects them from the cold, from corrosion and other elements.. If you live in an area that experiences extreme winter weather, then insulation may be necessary to protect your pipes and prevent freezing or bursting.

Will PVC freeze underground? ›

Thankfully, no. But ice does build up inside pipes, blocking unfrozen water from flowing. Pipes made of copper, steel, PVC, PEX and other plastics are all susceptible to freezing, with copper being the most vulnerable to ruptures when frozen.

How deep does a water line have to be to not freeze? ›

The classic rule-of-thumb procedure for avoiding cold-weather damage to water pipe is "bury it deep." If water lines are located below the lowest level of frost penetration—five to six feet or more in many cold region locales—they should be safe from freezing.

How long does PVC last underground? ›

Dig-up test results in the U.S. and around the world indicate that PVC pipe can be expected to provide reliable service in excess of 100 years. The average water main is failing at 47 years. Corrosion is the major cause.

Does PEX pipe reduce water pressure? ›

In fact, when correctly installed by a re-piping plumber in Las Angeles, PEX will eliminate low water pressure, red or brown rusty water, and even provide better tasting water.

How deep should PVC pipe be buried? ›

All PVC pipes should be buried at least 12 inches below the frost line so they won't rupture in freezing temperatures. However, where heavy traffic is expected, trenches will need to be at least 24 to 36 inches deep.

Can I use PVC pipe underground? ›

PVC and CPVC piping can be installed underground, but the installation must follow all ordinances, regulations, and codes. If you're planning on installing PVC and CPVC piping, make sure to pay special attention to local pipe installation techniques since it will be installed deep within a wide range of sub soils.

What size pipe is used for underground water lines? ›

Supply pipes are ¾ inch in diameter and individual components are ½ inch in diameter. Your water pressure decreases by about a half pound per square inch for every foot a pipe extends above your water supply, which is especially important when running new lines to an upper-level area of your home.

What are the typical materials used for underground drainage? ›

Since the 1970s, plastic has been the material of choice for many underground drainage pipe installations. Most common types include PVC and ABS simply because they serve the same purpose as their cast-iron and clay counterparts.

How much water can a 4 inch corrugated pipe handle? ›

1106.2 Size of Storm Drain Piping
PIPE SIZE (inches)CAPACITY (gpm)
7 more rows

Is PVC better than corrugated pipe? ›

Pros of solid PVC pipe:

Durability: This type of pipe is much more durable than corrugated pipe - it isn't penetrable by roots and is simple to unclog. Smooth walls: The walls of PVC pipe are smooth, so it is less likely to clog or to catch debris that slows water flow.

How long do PVC pipes last underground? ›

Dig-up test results in the U.S. and around the world indicate that PVC pipe can be expected to provide reliable service in excess of 100 years. The average water main is failing at 47 years. Corrosion is the major cause.

How deep do water lines not freeze? ›

The classic rule-of-thumb procedure for avoiding cold-weather damage to water pipe is "bury it deep." If water lines are located below the lowest level of frost penetration—five to six feet or more in many cold region locales—they should be safe from freezing.

How do you lay underground water pipes? ›

Laying your water pipe

The water service pipe should be laid between 750mm- 1350mm below ground, on a bed of sand, ducted and insulated as it enters the property and should be fitted with an internal stop tap and a compression fitted cap end. It's most commonly laid on private land up to the highway boundary.

What PVC is good for underground? ›

Generally, when choosing PVC thickness for residential plumbing, schedule 40 is considered ideal and works well for many underground residential applications. There may be extenuating circumstances that could result in the need to install higher than schedule 40, however.

What PVC should be used underground? ›

For residential plumbing, schedule 40 is the ideal PVC type. It has just the right diameter, unlike the other schedules which appear too thick.

Can Schedule 40 PVC be used underground? ›

Schedule 40 rigid PVC conduit, elbows, that are specifically marked for underground use are suitable for use underground only by direct burial or encasement in concrete. The UL listing says both 80 and 40 can be used in both above and underground installations.

Does water pressure increase with smaller pipe? ›

A smaller pipe would lessen the flow of water as well as reduce the pressure loss in the pipes. This in turn would cause more pressure but render a sprinkler system inoperative. This is because sprinklers need a certain level of flow working in tandem with pressure to function properly.

Does the size of pipe affect water pressure? ›

In water flowing pipeline, pipe size and water pressure are dependent on each other. Because if the diameter of a pipe decreased, then the pressure in the pipeline will increase. As per Bernoulli's theorem, pressure can be reduced when the area of conveyance is reduced.

Which is better copper or PVC for water main line? ›

PVC pipe is thicker than copper which also helps with impact damages and abrasions. Less noise compared to copper piping, even with higher water velocities and speeds. Easier installation vs copper pipes, especially for do-it-yourself enthusiast. Significantly cheaper than alternative option.


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