What is the most common size for residential copper water pipe?

The most common size for residential copper water pipe is 3/4 inch. This size is widely used for typical residential plumbing applications, including supply lines for kitchens and bathrooms. The 3/4 inch diameter allows for a good balance between adequate water flow and efficient pressure, making it suitable for the majority of households.

Copper pipe is available in various diameters, but it's important to consider the water demand of a home when determining the appropriate size. In most cases, 3/4 inch pipes can handle the water supply needs effectively without significant loss of pressure or flow rate, which is crucial for fixtures such as faucets, showerheads, and toilets that require adequate water delivery.

While other sizes like 1/2 inch are also used, especially for branch lines running to fixtures, they are not as common for the main water supply line in residential settings. Larger sizes like 1 inch or 1 1/2 inch are typically used in more specialized applications or in larger buildings, where the demand for water supply exceeds that of a typical single-family home.