Abstract: An energy dissipator for downwardly discharged water utilizes a hollow cone valve located in a chamber open to the atmosphere and arranged to direct water emerging therefrom at an angle inclined downwards from the horizontal towards a region of a surrounding wall, and a pair of troughs around the inner surface of the wall above and below the region with the open mouths of the troughs facing each other. The troughs serve to reduce considerably the incoming energy of the water in a relatively small volume, the effect being enhanced by splitting the water emerging from the cone valve into a series of discrete jets, between which air can flow.