Firstly, as I've said previously TS, if your going to start a thread, write an introduction PLEASE!, rather than just a bunch of links.
As for water being drugged, It's been known for many years that the average sewer rat has been increasing in size and varociousness. In truth, any drugs pumped into the sewers is usually after it's passed through humans or through "Waste Disposal". In fact there is even the point that certain hormones produced by men and women can have catalysing effect on the water systems.
To put it bluntly, Ladies having that time of the month contribute to rat size.
When looking at water treatment, there have been steps to try and remove bacteria, which does mean that alot of chemicals are used within the process of cleaning water. This water is then pumped through holding areas to "Settle", before eventually being piped to houses or pumped into reservoirs.
The only other way that drugs end up into the water system would be through junkies flushing their stash or from chemical concotions created from fertilizers and the like.