IMAGE: The Hawkesbury riverFlickr: Karl Baron (CC BY)Posted Tue 13 Mar 2018 at 4:09amTuesday 13 Mar 2018 at 4:09amTue 13 Mar 2018 at 4:09am Treated sewage makes up to 20 per cent of the Hawkesbury's river flow where the North Richmond Filtration Plant draws its water.(Flickr: Karl Baron (CC BY))ShareCopy linkFacebookX (formerly Twitter)