Answer
Approximately:
$2.4 \times 10^{11} \text{ liters/year}$
$2.4 \times 10^{11} \text{ quarts}/\text{year}$
$2.4 \times 10^{8} \text{ m}^3/\text{year}$
Work Step by Step
The population of the US is approximately $330$ million people $(3.3 \times 10^8)$.
An average person drinks about 2 liters of water per day.
$\text{Total liters per year per person }= 2 \text{ liters/day }\times \text{days/year}=730\text{ liters/year}$
Multiply by total population:
$\text{Water consumed per year }=730\text{ L/person/year } \times 3.3 \times 10^8 \text{ people} \approx 2.4 \times 10^{11} \text{ liters/year}$
Convert to quart:
$1\text{ liter} \approx 1\text{ quart}$:
$2.4 \times 10^{11} \text{ liters/year} \approx 2.4 \times 10^{11} \text{ quarts}/\text{year}$
Convert to cubic meters:
We know that $1\text{ L} = 10^{-3}\text{m}^3$, so:
$2.4 \times 10^{11} \text{ liters/year} \times 10^{-3} (\text{m}^{3}/\text{liter})= 2.4 \times 10^{8} \text{ m}^3/\text{year}$
