What is the minimum required size of water service pipe for domestic use?

The minimum required size of water service pipe for domestic use is 3/4 inch. This size is typically recommended to ensure that there is adequate water pressure and flow for standard household needs. A 3/4-inch pipe allows for sufficient capacity to supply water to toilets, sinks, showers, and other fixtures without significant pressure drop, especially when multiple outlets are in use simultaneously.

Using a smaller diameter, such as 1/2 inch, may result in insufficient flow to meet the demands of a typical household. In contrast, larger sizes, like 1 inch or 1 1/4 inches, are usually overkill for a standard domestic supply line, adding unnecessary cost and complexity to the plumbing system. Therefore, 3/4 inch strikes a balance between adequate performance and practical installation for residential plumbing applications.