Jogger jumps into Chestnut Hill Reservoir to save man, dog

Obviously a good outcome here, but a cautionary tale insofar as it seems like a heroic thing to do to jump into the water to save a struggling person, but without some training in how to do so, these stories sometimes end with two drowned people (and a dog). The human survival instinct is strong, and a person will often do irrational things like claw and push a rescuer underwater (not irrational actually, they are using them as a way to get their head above water). I won't post it here as it is quite disturbing, but you can see this in action via a YouTube video from buffalo where two men drown instead of one for exactly this reason.

Reservoirs are the first stage in the water purification process, and perhaps the most ominous sounding issue around reservoir swimming is the machinery which is used to carry out this process.

This is often the area in which water companies play up the possible dangers most, talking about unpredictable currents and suction pipes. Yorkshire Water, for example, say that ‘strong currents lurk beneath the surface, particularly if water is being taken out through massive pipes’ and United Utilities that ‘there may be hidden obstacles beneath the surface…this may be machinery from our treatment works or even broken glass or other rubbish.’

There is little evidence of accidents where the alleged dangers of currents or machinery have played a role. One watersports centre on a reservoir (when asked how it was safe for people to swim at events, and sail, windsurf and kayak year round) pointed out that these activities were always supervised and participants wore buoyancy aids, and had rescue boats and trained staff on hand. They were not aware of any machinery in the water, with the exception of the valve tower.

It clearly will be true that swimmers could get into difficulty by dams and water outlets.