N-O

Noise correlator

Device that is used at two points on the land surface to pinpoint leaks through the sound that is generated by water escaping (7)

Non-degradable plastic

Plastic that does not break down over time (12)

Non-point source of pollution

Source of pollution that encompasses a wide area, the exact point of origin being difficult to ascertain (4)

Non-revenue water

Water that is supplied by a water utility but from which no income is received (7)

Operation

Routine activities and procedures that are implemented to ensure that the water supply system is working efficiently (6)

Operation and maintenance (O&M)

(of a water supply system) all the activities needed to run the system continuously to provide the necessary service (6)

Organic matter

Material that comes from living organisms (4)