How much water in gallons is used taking baths

Depends on the size of the tub they all vary

So, the tub is rarely filled to capacity before taking a bath. A low-flow shower head uses about two gallons a minute, or 20 gallons for a 10-minute shower. A standard shower head uses 2.5 gallons a minute, or 25 gallons for 10 minutes. Either way, the shower saves water - as long as you don't go past 10 minutes.