This sounds like you are trying to make an improper connection. I don't know what a "water chiller" is for sure, I assume it is a device to cool your drinking water, and if so, you could create a cross contamination problem if you connect this to a hose. As far as the fittings needed, it would take a combination which isn't too hard to do, but I'd proceed with caution on this. When a water supply line is split to be able to use water inside and for irrigation, a backflow preventer or anti syphon valve is required to keep irrigation water which can easily be contaminated, from getting back into the household supply.