Suddently I feel bad about drinking milk. And bad about eating burgers (old feeling, but new reason).

In a day, 

Europeans use about 50 gallons of water. 

Americans use 100 gallons of water. 

The people living in Sub-Sahara-Africa use 2-5 gallons of water.

It takes

10 gallons to make a single slice of bread.

713 gallons to produce a cotton T-shirt.

1000 gallons for just one gallon of milk.

and 634 gallons to produce one burger.