Mayhaps anyone provide assistance in determining how long it would take to reduce a specific volume of water (well, a solution, mostly water) to a smaller volume by boiling it? i.e. boil 15 gallons down to 5 gallons? Rule of thumb I've used is 5% of volume per hour, but I know it varies based on surface area, yet have little idea to figure it out. By this I roughly figure close to 48hrs. Actual task at hand would be reducing ~30ish gallons to 4 gallons via boiling in a container with a surface area of ~254 sq. in.