Hi, Dave. This is my opinion only and should not be considered in place of contrary opinions of competent authorities. However, when you conside the actual amount of Diazinon in a teaspoon of the product--a couple of percent-- and then you dilute it in 5000 gallons of water, you are dealing in some pretty low concentrations. Just from a potential liability standpoint, I'm surprised that yuou got anybody to say that it was safe. But, personally, I don't think that I would be too concerned.