How much water would you add to 2 1/2 gallons of bleach to make a 10 bleach solution?

To get the amount of water you would add to 2.5 gallons of bleach to make 10% bleach we shall proceed as follows:

let the amount of water be x

100*2.5+0x=10 (x+2.5)

250=10x+25

10x=225

x=22.5

thus the answer is, 22.5 gallons of pure water should be added in the bleach.