Non-point sources of water pollution are

Non-point pollution comes from spread-out, hard-to-pinpoint origins, so it is diffuse, episodic and difficult to monitor.

Statement 1 is wrong because a specific location describes a point source instead.

Statement 2 is right since non-point pollution is diffuse across the landscape.

Statement 3 is right as it is episodic, often tied to rain events, while Statement 4 is wrong because being identifiable fits a point source.

Statement 5 is right since such spread-out sources are hard to monitor and control.

Agricultural runoff carrying fertilisers and pesticides is a classic non-point source.