type M type L copper pipes
Family Handyman

Because of its enduring properties, copper has long been the most popular material in plumbing. It comes in different varieties, all labeled with different letter grades: K, L, M and DWV types. Type L and Type M copper pipes are most commonly used for water supply and heating systems in residential and light commercial buildings.

How To Select the Best Copper Pipe for Plumbing

Some factors to consider when choosing the right pipe are water chemistry compatibility, pipe type and wall thickness, corrosion resistance and longevity. Health and safety considerations are also important. For example, any supply pipe for drinking water has to be lead-free.

Cost

According to Neighbourhood Plumbing, Type M is the best option if you’re on a budget. Type L is thicker, which makes it more expensive. While Type M is the more affordable option, the walls on it are thinner, so many plumbers still prefer Type L for long-term reliability.

Durability

Type L pipes are more durable. They have thicker walls, which make them more resistant to corrosion. This type of pipe is often used in underground and high-pressure applications. Type M pipes work better for low-pressure systems inside homes where heavy wear and tear are less likely.

Water Pressure Handling

Water pressure handling is also a very important factor. Since Type L has thicker walls, it can handle higher water pressure and is ideal for commercial buildings or homes with powerful plumbing systems. Type M works for standard water pressure.

“Think about where you’re installing the pipes. Type M works well for residential water supply lines that don’t require extreme durability,” Neighbourhood Plumbing says. “Type L is commonly used for commercial settings, underground installations and places where plumbing fixtures need extra reinforcement. Some building codes even require Type L for certain applications, so be sure to check local regulations before making a decision.”

Versatility

Type L is more versatile because it can be used in both residential and commercial settings, making it a top choice for professional plumbers because of its adaptability.

When To Use Type L and Type M Copper Pipe Sizes

A Type L copper pipe is recommended when you need strength and protection. But for normal in-wall household plumbing, Type M works fine.

When it comes to copper piping for water lines, acidic water with a pH of seven or less can be hard on copper pipes. If you have a well and find out from testing that the water is acidic, you may want to use the thicker-wall Type L pipe or plastic CPVC pipe and fittings. Note that most city water, even in areas of the country where the water is acidic, is balanced to eliminate this problem.

According to veteran plumber Charlie Avoles, the best alternative to copper is PEX (flexible plastic pipe). “We’re seeing that many properties of PEX are tougher than copper, and PEX doesn’t appear to get fragile with age and exposure to ultraviolet light like CPVC does.”

FAQ

Which copper pipe is better for drinking water systems?

While both L and M type copper pipes are used for drinking water systems, Type L copper pipes are used more often because of their durability. They have thicker walls, making them a better option for underground water supply.

Can Type M copper pipes be used for hot water lines?

Yes. Type M copper pipes are usually used for hot water systems in residential buildings. Hot water lines must pass water at a temperature between 120 degrees Fahrenheit (49 degrees Celsius) and 140 degrees F (60 C), and Type M copper pipes are resistant to that temperature.

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