A symbol for 1000 (not one million) cubic feet per day, a unit of water flow used by many U.S. water supply companies and agencies. 1 Mcfd = 19.665 liters (5.195 U.S. gallons) per minute
Russ Rowlett (Director), How Many? A Dictionary of Units of Measurement, Center for Mathematics and Science Education University of North Carolina, USA 2005. http://www.unc.edu/~rowlett/units/dictA.html, (Unit of Meas and Covr Factors - Amer) {608}