Water piping and Water main

Water main and water piping are semantically related in waterway topic. In some cases you can use "Water main" instead a noun "Water piping", when it comes to topics like conduit, water pipe, waterline, water line.

Water main noun - Main (a pipe or conduit) for conveying water.

Water piping and water main are semantically related in waterway topic. You can use "Water piping" instead a noun phrase "Water main", if it concerns topics such as conduit, water pipe, waterline, water line.