|Make Some Caps With SASS!|
Go to the Sunset Sarsaparilla factory in the Mojave Wasteland and collect every single Empty Sunset Sarsaparilla Bottle you can find there. There should be around 820 there. Don't worry about overloading your carrying capacity because you won't have to fast travel anywhere. Once you've collected all of the empty bottles, walk outside and use your Big Mountain Transportalponder to travel to The Sink. Once you're there, use the sink to fill up the bottles with purified water. You can then sell those to The Sink Central Intelligence Unit for 20 per bottle, which works out to 16,400 caps.