Not: tidak and bukan

Actions and qualities

Use tidak for ordinary statements denying an action or quality: Saya tidak bekerja (I do not work); Air itu tidak panas (That water is not hot). The ending or prefix of the verb does not choose the negative: both tidak makan and tidak menulis use tidak. panas = hot; mahal = expensive.

Identity and ownership

Use bukan to deny a noun identity: Dia bukan guru (He/she is not a teacher); Itu bukan tas saya (That is not my bag). This is the basic neutral distinction; contrastive uses can be more flexible.

Existence

ada = there is/are; tidak ada = there is/are no. Belum, meaning not yet, is introduced with time/aspect later. Do not use bukan as a universal translation of not.

Tidak ada air.