Altogether, the US receives about 5 trillion gallons of precipitation a day. Most of that (63%) gets returned to the atmosphere via evapotranspiration. Much of the rest ultimately flows into the Gulf of Mexico (11%), Pacific Ocean (6%), and Atlantic Ocean (2%). About 10% gets stored in surface bodies of water (lakes, reservoirs) or underground aquifers, and 6% flows back into Canada. The remaining 2% is consumed by people in various ways.