Water

[Bazile]

I know that water companies get their water from Reservoirs and other places .

Here's a question .
What's to stop some person bent on harming folk from depositing something harful in the reservoirs ?

I assume that the water taken from reservoirs are tested for various contaminants

Would one of those tests be for poisons , for example ?

[jno]

///The good news is that poisoning a water system is hard to do. Putting a few drops of cyanide in someone’s glass will lead to a gruesome death. Putting a few drops, or even a few barrels, in a reservoir is pointless. Reservoirs generally hold anywhere from 3 million to 30 million gallons of water. ///

https://slate.com/technology/2014/01/how-safe-is-our-drinking-water-threats-from-chemical-spills-pathogens-and-terrorism.html

[Atheist]

Baz, the idea of spiking reservoirs with e.g. LSD has been around for a long time. And presumably still is, as I am sure that all countries have bods who work on nothing else but devising subtle attacks on other countries. Fidel Castro's cigars springs to mind, as does cyber attacks e.g. trollbots who infiltrate social media to provoke dissent and squabbling among populations in order to undermine their nation's resolve.

[Buenchico]

If you were to empty a full tanker load of, say, cyanide into Kielder Water, the average resulting concentration of cyanide in the reservoir would be approximately 1 part in every 17,500 parts. With all sorts of nasty chemicals all around us there days, we probably ingest poisons at those sorts of concentrations nearly all the time, without coming to any serious harm.

[davebro]

They did mistakenly dump a load of chemicals (aluminium sulphate?) into a local water supply in the south west. I believe it caused some serious health problems.

[Buenchico]

It's probably easier for someone to cut off the supply from a reservoir altogether (e.g. by blowing up the pipeline that it feeds), rather than to contaminate the water itself:
https://en.wikipedia.org/wiki/Water_supply_terrorism

[douglas9401]

Local youths did indeed 'dump' something in a water plant locally some years ago.

Although we were spared the graphic detail of the offending objects was obvious what had been done and it caused a fair bit of disruption for a while.

Manky little knobs.