M is thinner than L and will not last as long. The M copper in my home lasted for 17 years before it started developing pinhole leaks. I had the affected pipes replaced with L. Answer from zlandar on reddit.com
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Family Handyman
familyhandyman.com › home › skills › plumbing › pipes
Differences Between Type L and Type M Copper Pipes
September 10, 2025 - 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.
Discussions

Do I have Type M or L copper?
L copper has blue lettering and M copper has red lettering. More on reddit.com
🌐 r/askaplumber
71
13
June 22, 2024
Type L vs M copper pipe?
Same o.d., same fittings, you won't notice a difference in flow from the change in i.d. More on reddit.com
🌐 r/Plumbing
62
6
September 22, 2021
Type M copper for whole house repipe?
M is thinner than L and will not last as long. The M copper in my home lasted for 17 years before it started developing pinhole leaks. I had the affected pipes replaced with L. More on reddit.com
🌐 r/askaplumber
27
2
December 12, 2023
Type M or L copper for hot water heater supply and output? Any risk in using new type L and coupling to existing type M?
At one point, not that long ago, code here used to be Type L for domestic water lines, Type M was used for heating only. Now, it’s Type M for anything… More on reddit.com
🌐 r/askaplumber
7
5
May 29, 2022
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Reddit
reddit.com › r/askaplumber › type m copper for whole house repipe?
r/askaplumber on Reddit: Type M copper for whole house repipe?
December 12, 2023 -

I just had a 3rd plumber come out to give me an estimate to replace galvanized and he said they use type M copper. The other 2 said they use type L copper. I'm pretty sure type M isn't even allowed here (Chicago).

Do you think type M is fine for residential supply? He said they could do type L if I really want but it would be "probably $800 more.". He said M is fine and will last 50 years+. Still waiting for his overall quote to compare with the other 2, but I think he will be the lowest bid.

For what it's worth my whole basement is exposed ceiling (easy repairs), but it may be finished eventually.

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The Motley Fool
fool.com › investing › stock-market › market-sectors › materials › metal-stocks › copper-stocks
5 Best Copper Stocks to Consider in 2026 | The Motley Fool
1 day ago - Anyone can buy copper stocks. Here's a step-by-step guide on how to add one to your portfolio: Open your brokerage app: Log in to your brokerage account where you handle your investments. Search for the stock: Enter the ticker or company name into the search bar to bring up the stock's trading page. Decide how many shares to buy: Consider your investment goals and how much of your portfolio you want to allocate to this stock. Select order type...
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PexUniverse
pexuniverse.com › copper-pipe-dimensions-specs
K, L, M Copper Pipe Dimensions & Technical Specifications - PexUniverse
OD - Outside Diameter; for copper pipe, OD is always 1/8" larger than CTS size. For example, the OD of 1/2" CTS pipe would be 5/8" and for 1" CTS pipe would be 1-1/8". ID - Inside Diameter Wall Thickness - denotes the thickness of the pipe wall. The main difference between L, M and K type copper pipes are their wall thickness.
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Fixed Today Plumbing
fixedtoday.com.au › fixed today › blog › type i type m copper pipes
The Differences Between Type l And Type M Copper Pipes ‐ Fixed Today
March 5, 2025 - Copper piping is recycled into numerous other materials at the same metal purity, making it sustainable and cost-effective. With soft copper pipes, you can easily shape and bend them without using tools. On the other hand, rigid copper pipes demand specialised tools for cutting and joining. ... Four commonly used copper pipes are used in residential and commercial plumbing: Type K, Type L, and Type M.
Find elsewhere
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COPPERTUBINGSALES
coppertubingsales.com › collections › type m hard copper pipe 20 ft. lengths › 1/2 type m hard copper 20 ft lengths
1/2" TYPE M Hard Copper 20 FT Lengths — COPPERTUBINGSALES
1/2 TYPE M Hard Copper 20 FT Lengths
Additional freight required to ship 20 ft lengths Manufactured to spec ASTM B88 is the Standard Specification for Seamless Copper Tube , ANSI/NSF Standard 61 Drinking Water System Components. All of the specifications require a minimum copper plus silver content of 99.9% and phosphorus content between .015 - .040%. As indicated by the · compositional requirements, the copper tube is essentially lead free. NSF 61 , Alloy C12200 Called by the NOM ID size Type M is used for domestic water-, service and distribution-, fire protection-, solar-, fuel and oil-, HVAC-, compressed air-, oxygen-
Price   $40.60
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Ferguson
ferguson.com › pipe & tubing › copper tubing › type m tubing
Type M Copper Pipe | Ferguson
Skip to main content Skip to footer content · Home / All Products / Pipe & Tubing  / Copper Tubing / Type M Tubing · 14 Products Close · In Stock · Brooklyn, 8805 18th Avenue · Type M Hard 14 14 Products Type M Hard · There are no matching search results.
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Lowe's
lowes.com › plumbing › pipe & fittings › copper pipe & fittings
Streamline 3/4-in x 5-ft Copper Type M Pipe MH06005 at Lowes.com
Shop Streamline 3/4-in x 5-ft Copper Type M Pipe in the Copper Pipe & Fittings department at Lowe's.com. Streamline® Copper Tube sets the standard for quality, consistency and service in the plumbing industries. Copper Type M Pipe is perfect for residential
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Continental Steel
continentalsteel.com › all categories › copper and brass › tubing and pipe › copper water tube - type m › view items
Copper Water Tube - Type M
Copper Water Tube - Type M Tubing and Pipe · /Asset/Copper-Tubes.jpg · Close Window · 20' Straight Lengths Specifications: CDA 122 ASTM B88 UNS C12200 Nominal Composition: Copper: 99.9% Phosphorus: .02% 1 - 10 of 10 | Results Per Page · 25 · 50 · 100 ·
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Grainger
grainger.com › product › STREAMLINE-Tubing-Copper-22FC81
Tubing: Copper, 4 in, Type M, 10 ft, Straight
We cannot complete your request due to a technical difficulty. You may return to the previous page or go to the homepage and explore other options. For immediate assistance please call us
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NuComfort
nucomfort.com › 1-1-2-x-10-type-m-copper-tubing › 83333
1-1/2" X 10' TYPE M COPPER TUBING | 83333
Close menu · Show all categories Copper Pipe Back · Show Copper Pipe · Generic · Product Number: 83333 · Manufacturer Code: 1-1/2X10 M Please login to see prices · Specifications · Close menu · General Information · Description · Close menu · Close menu ·
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Ferguson
ferguson.com › product › 1-1 › 4-in.-x-20-ft.-type-m-hard-tubing-mhardh20 › 37078.html
1-1/4 in. x 20 ft. Type M Hard Tubing | Ferguson
Copper · Material Type: C12200 · NSF: NSF 61, NSF 61G · NSF Certified: Yes · Origin: Domestic · PipeTubing Size: 1-1/4 in · Product Type: Copper Tube, Type M · UPC: 685768236320 · Wall Thickness: 0.042 in · 0 · View All · Ferguson.com no longer supports Internet Explorer.
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The Home Depot
homedepot.com › p › Mueller-Streamline-1-2-in-x-2-ft-Copper-Type-M-Pipe-MH04002 › 100553697
Mueller Streamline 1/2 in. x 2 ft. Copper Type M Pipe MH04002 - The Home Depot
Enjoy the MUELLER STREAMLINE 1/2 in. x 2 ft. Copper Type M Pipe MH04002, durable used mainly behind walls inside a residence, routes water from a service line and water heater to a fixture from The Home
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Westlake Ace Hardware
westlakehardware.com › home › what do the letters ‘k,’ ‘l’ and ‘m’ on copper tubing mean?
What do the letters 'K,' 'L' and 'M' on copper tubing mean? - Westlake Ace Hardware
October 13, 2020 - Type K is the heaviest. Type L is medium weight and used most often for water lines in homes. Type M is thinner and is used underground or for light