Water Mouth (水口)

The place where water enters or leaves a site, and one of the form school's key observations. The water mouth is the point at which a stream, drain or road — anything that carries flow — enters or exits a site. The tradition reads its position and its shape as a statement about whether what arrives stays.

It belongs to the classical vocabulary of the tradition. The place where water enters or leaves a site, and one of the form school's key observations. In modern application the term is extended to roads and to drainage, which is a documented extension rather than a departure — the classical sources already treat any channel of movement as water.

The classical sources treat water as the primary indicator in landscape reading and the water mouth as its most important single detail: the preference is for an entry that is visible and an exit that is concealed. It is grouped under Water (水) in the five-element system.