Layman's Explanation Greatest Hits right there. Except I was actually curious so I converted it. Assuming a 30-gal tub, it's about 267 tubs/field-hour.
Hrm - "To start, the standard bathtub will hold roughly around 80 gallons (302 liters) of water. Much smaller bathtubs can only hold around 40 gallons (150 liters) of water, which typically are more suited for smaller children or function more as a shower space."
