You can watch "Waterloo Road" through several options:

• It is available to stream for free with ads on The Roku Channel.
• In the UK, you can stream it for free on BBC iPlayer.
• You can purchase episodes on Amazon Video and Apple TV as downloads.
• In the US, some seasons (1-4) are available on Roku Channel, and many episodes are also available on YouTube.
• The official Waterloo Road YouTube channel offers episodes and clips.

So, depending on location, the best legal options are Roku Channel, BBC iPlayer (UK), Amazon Video, Apple TV, and YouTube.