Sprinkler - watering with a typical sprinkler using a standard 5/8" garden hose for one hour uses about 1,020 gallons of water, if you water three times per week, that's about 12,240 gallons per month.
Shower - water used in a 20 minute shower depends on the shower head. If you are using a low flow showerhead, less water will be used but the pressure will be less. If you use a rain type shower head, more water will be used. On average, two gallons of water is used each minute of showering.
Water Leaks - the average household's leaks can account for nearly 10,000 gallons of water wasted every year and 10% of homes have leaks that waste 90 gallons or more per day (32,850 gallons per year). EPA information on water leaks