4. NI Water
- Chief executive: Sara Venning
- Pre-tax profit: £54.4m
- Employment: 1,222
- Pay bill: £57.3m
NI Water provides water and sewerage services to 840,000 homes and businesses, contributing to the health, economy and environment of Northern Ireland.
It provides 560 million litres of fresh drinking water and takes away 330 million litres of wastewater, which it treats before returning to the environment.