Genocide unlikely as people can stop drinking after finding out it is poisonous, especially if the poison is fast acting.

River ecocide will probably alert the authorities. www.waternz.org.nz/Story?Action=View&Story_id=242…

It has to be a slow acting poison and not easily detectable. example…PFAS - www.youtube.com/watch?v=SC2eSujzrUY

Seems like there has been break-ins though to water supply - linkedin.com/…/elisabethbraw_is-russia-trying-to-…