Is there different levels of quality in copper plumbing pipe? I see copper pipe at Home Depot and I assume plumbing supply stores sell it too. Does pretty much everybody sell the same quality of copper pipe, or are there differences I should be aware of?

By copper pipe, I mean the typical 1/2" and 3/4" copper pipe used in residential plumbing applications.


6 Answers 6


There are different grades and types of copper pipe that you of course should be aware of. However I think your question is whether copper pipe is really a commodity type product - whether there's a difference between products of the same grade / type made by various manufacturers and sold by various retailers and wholesalers.

This is a common question but it's a tough one.

One the one hand, there are standards that apply to these products and any product that meets the standard should be adequate for the purpose. That may lead you to conclude that standardization makes these products essentially commodities.

On the other hand, big retailers press manufacturers very very hard for low pricing, and are not nearly as tough on quality; DIY customers are not as demanding as the plumbing contractors, maintenance people, etc. that shop at plumbing supply houses catering to contractors. Big box retailers are going to cater to their customers and their customers are primarily concerned with price.

It's very possible that in some cases the same product from the same manufacturer is identical quality whether purchased in a big box store or in a specialty supply house. It's also very possible that a brand may have to lower their quality (within acceptable standards) to win a spot in a big box store. It's even possible that a manufacturer may make the same exact product to a higher standard for supply houses and to a lower standard for big box retailers.

In my opinion, I have seen all three of these scenarios unfold over the last ten years as big box stores have grown and become more powerful in the market.

  • I have one nitpick , as far as manufacturers go, there is very little upside in maintaining multiple production lines for specific customers or binning/selective testing for the same part number for commodity type products, if you are purchasing the same part number from a big box vs contractor retailer it should not differ within the stated spec, if there is a unique part number or part number suffix for one retailer then that is cause to worry. On the other hand when a big box retailer places a large order, they may not have their "Best Shift" running the line
    – crasic
    Mar 13, 2019 at 21:15
  • @crasic - I think you definitely have a point but it depends on the product, in some cases it's not worth while to differentiate but in others it is. Mar 13, 2019 at 22:58
  • Sure, no argument, but the second point I am getting at is a manufacturer who reuses the same part number for effectively multiple parts would not be reputable regardless of where you buy it.
    – crasic
    Mar 14, 2019 at 0:06
  • I remember when working for a window and door manufacturer that a certain orange colored big box store accounted for over 35% of the annual company sales. Needless to say they had a significant bargaining chip!
    – corsiKa
    Mar 14, 2019 at 0:24
  • 2
    It's easy to imagine that factory procedures can be abridged to temporarily lower the overall quality of output, or tightened up to improve consistency, using the exact same production line. As mentioned in a prior comment, the best workers may already have attention-to-detail and experience that yields superior results from the same process, and a careful manager might put them all on a shift together for making the highest grade of product possible, reserved for select clients.
    – Darren
    Mar 14, 2019 at 13:51

There is copper tubing and there is copper water tube as defined in ASTM B-88. Tubing is usually soft and comes in coils. Water tubing is usually cold drawn and comes in straight lengths. K, L, and M are different wall thicknesses of water tubing ; an example for size 3/4 " is- K = 0.065", L= 0.045", and M = 0.032". All 3/4 copper water tube has a 0.875 " outer diameter. ( My ASTM B 88 is old but they don't change these dimensions.) . However K is often annealed so also comes in coils. Tubing and water tubing are the same composition , more or less pure copper. So ASTM B 88 water tubing is the moral equivalent of pipe but with a different name.


There are a few different kinds of copper pipe at Home Depot (and I assume other home stores). For rigid copper pipe, there is Type M and Type L.

Type M is thinner walled and normally has red markings on it. Type L is quite a bit thicker and will have blue markings. The color of the markings could be brand specific, but that's what I'm used to seeing.

Also there is bendable copper that is normally used for A/C lines. It is sold in rolls and usually not used for water.

The letters don't stand for anything. They are in alphabetical order. There is also Type K which is thicker and made for direct burial, but its not usually found in retail stores.


There are many different types of copper.

There are hard measured by inside diameter drawn and soft drawn measured by outside diameter. Of the hard drawn (pipe lengths) there are type DWV, M, L and K. DWV is the thinnest and K is the thickest. For residential type K is not used often and type M is the most common.

Soft drawn (coils) come in the same types but a 5/8 soft copper fits in a 1/2 copper fitting...

The reason for the seemingly over complicated answer is that Home Depot and Lowe's will sell soft copper rolls in 1/2 inch and 3/4 that are domestic waste and vent (type DWV).

The two types a DIYer will run into are M and L. But watch out for the soft copper from big box hardware stores.


Would it better to go with Type K if you need to buy from a big box store (or anywhere else for that matter)? Aside the increased cost, is there any reason not to use K?

  • Type K is a thicker wall so it will restrict flow slightly. It's very heavy. It's hard to cut. It seems to cost as much as silver... Lol
    – Joe Fala
    Mar 20, 2019 at 3:17

from the plumbing code 604.3 Copper or Copper Alloy Tube. Copper or copper alloy tube for water piping shall have a weight of not less than Type L. Exception: Type M copper or copper alloy tubing shall be permitted to be used for water piping where piping is above ground in, or on, a building or underground outside of structures.

M is suitable for exposed and inside walls in residential dwellings. L is suitable exposed and for the water pipe ground for the service entrance to a dwelling. K is used for underground piping inside buildings and annealed copper rolls. K can be used in lieu of l and m and l can be used in lieu of m.

M will develop pin holes sooner due to its thin walls and is also subject to physical damage. L is better and k is the best but is extremely expensive but is good where there is corrosive water or wet soils. Plastics are now a much more affordable choice for water piping and are corrosion free. DWV is an acronym for DRAIN, WASTE, VENT and refers to sewer system piping it is very expensive in copper and rarely used for drain lines.

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