Copper water lines have different grades.

Copper water lines have different grades.

Copper water lines used in your home or building have different grades. They are standard Type M or thick wall Type L. There is also a Type K  copper pipe which is used underground which has even thicker walls. Local plumbing codes dictate which grade can be used, where and how it may be used. Check with your local plumbing or building inspector if you are not sure which you need to use.