Did Hefe today and when i was done i had to run out and buy another gallon of water to bring it up to the 5 gallon mark. Usually this does not happen and I have enough with 6 gallons, I bought an extra gallon sense I increased the boil time to 90 minutes from 60. However this still seems excessive. It did start to rain at the end of the boil. Could barometric pressure have effect on loss to evaporation.