To add to that, getting attacked using a water cannon during freezing weather, like during the Dakota Pipeline protests, will literally give you hypothermia [0] even if it doesn't blind or maim you. Not to mention that the cops used a combination of tear gas, baton rounds, and water cannons during that protest.

[0] https://www.nbcnews.com/storyline/dakota-pipeline-protests/d...

You're not supposed to hit people in the face with full blast at short distance. That's why these things have multiple settings. The high pressure tight beam is meant for large distance.

Tear gas has a similar problem: a tear gas cartridge in the face may blind you (or worse). Wikipedia says "As with all non-lethal or less-lethal weapons, there is some risk of serious permanent injury or death when tear gas is used. This includes risks from being hit by tear gas cartridges that may cause severe bruising, loss of eyesight, or skull fracture, resulting in immediate death. A case of serious vascular injury from tear gas shells has also been reported from Iran, with high rates of associated nerve injury (44%) and amputation (17%), as well as instances of head injuries in young people." [1]

1: https://en.m.wikipedia.org/wiki/Tear_gas

You're also not supposed to shoot baton rounds ("rubber bullets") directly at people's heads. This does nothing to stop police from shooting people in the head. It seems a common problem with all of these non-lethal weapons is that they are actually lethal in the hands of a cop.