I am going to begin vending cold brew at parties/pop-up events with the Toddy process, what are good methods to assure that I have optimal water quality with as little overhead as possible? I will brew between 12-18 gallons of cold brew for 350-400 people.
I typically buy the giant water jugs that they use for office water coolers. They sell them at nearly all grocery stores and compared to coffee, it's pretty inexpensive. I'd say if it starts taking you more than 20 minutes to move the water by hand, then congratulations on your success, and it's time to buy a filter. If you filter, you'll have the overhead of maintaining the filter and ensuring whatever water supply you have is being filtered well enough, but until then -- just buy it from higher end drinking water sources in large jugs or bottles.