1. Trouble.

Nuttall's Standard dictionary of the English language By Nuttall, P.Austin

• hotwater,
• got water,
• bot water,
• not water,
• jot water,
• uot water,
• yot water,
• hit water,
• hkt water,
• hlt water,
• hpt water,
• h0t water,
• h9t water,
• hor water,
• hof water,
• hog water,
• ho6 water,
• ho5 water,
• hot qater,
• hot aater

The adjective form of "hot water" is "hot".

The plural form of the word "hot water" is "hot waters".

The singular form of the word "hot water" is "hot water" itself. The word does not change when it is singular or plural.