Ductility is a physical property.
A physical property of a material is a property that can be measured or observed without changing the composition of the material.
In this case ductility is a physical property. It is defined as the  property of a material associated with the ability to be drawn or stretched into a wire without breaking. The chemical identity of the material is not affected, that is  it does not change. 
Example of ductile materials include gold, silver, copper, erbium, terbium and samarium.
Other examples of physical properties are:
1. Solubility
2. Melting point.
3. Boiling point.
4. Color
5. Density.
 
        
                    
             
        
        
        
so you’d need to find the amount of gallons your family uses in 11 minutes and subtract 73000 from that number
i used the same formula, came up with 80300 gallons a year, and subtracted 73000 from it to get
7300 gallons are saved by reducing showering time by one minute