The Centers for Disease Control and Prevention recommends scrubbing the hands with soap for at least 20 seconds, then rinsing them thoroughly. Assuming it takes about five seconds to rinse the hands, and the faucet being used is new, it takes 1.04 gallons of water to wash the hands.
The Mayo Clinic states that anti-bacterial soap is actually no better in eliminating bacteria than regular soap, and that anti-bacterial soap may actually be hazardous in the long run because of bacteria developing resistance to the product. Additionally, it's not necessary to use hot water when washing your hands because temperatures as low as 40 degrees Fahrenheit can get hands clean.