Exactly how environmentally unsafe are those "anti-microbial agents"? Pretty darn, I'm willing to wager. If it's something like triclosan for example, it'll help build resistance in bacteria and such, whilst causing damage to water-living organisms such as molluscs etc. These are very sensitive to triclosan.
I personally wouldn't put my own convenience and comfort so much above the well-being of the planet as to go and install an unnatural and unneccessary product such as this in my garden.