 Centimetre or millimetre of water

Centimetre of water (cmH₂O) and millimetre of water (mmH₂O) are units of pressure. They define how much pressure is exerted by a column of water of a certain height. 1. **Centimetre of Water (cmH₂O)**: - 1 cmH₂O is defined as the pressure exerted by a column of water that is 1 centimetre high at standard gravity (approximately 9.