The water supply to a home is usually obtained from a city water supply, where the water is treated and billed as a utility, or from a well, where the water is not treated and can have varying quality over time. (Well water is usually free, albeit after permit costs.) However, those on city water may want to consider adding a well to their property if they're in an area that allows wells within the city water district. The addition of this extra source of water is a great help for your property and even your budget, despite initial drilling costs.
Water is a precious resource, but drinking water is even more precious. This is water that's been treated and deemed safe to drink. There's no reason to use drinkable water on something like a lawn; well water would do just fine assuming the well water wasn't contaminated with something like pesticide runoff or harmful bacteria. When you plan your home's yard and surrounding landscaping, you could go with very drought-resistant designs, or you could use well water if you had it available to you.
This can also help your bill tremendously. Using city drinking water for your lawn can drive up your water bill substantially, but using well water shouldn't affect the bill at all. As mentioned, you do have initial drilling costs to take into consideration. But if you have a large property and plan to stay there for a long time, the well should eventually pay off.
Keep in mind that the water in a well can be perfectly drinkable itself. However, it's more prone to fluctuations in quality that can make it less suitable for regular drinking compared to city water. If you have a choice between well and city water for landscaping, chances are well water will be a better option.
A well obviously provides another source of water, but it can serve as a valuable source of water if something happens to the city's supply. City water treatment plants and reservoirs can become contaminated with bacteria or pollutants. If you have a clean, drinkable supply of water from the well, and the problem with the city water system has nothing to do with any of the local ground sources (i.e., the contamination happened at the plant) then you can still have drinking water for the time that the city system is out of commission.
You'll find that your city has permitting processes and other guidelines regarding wells (if the city allows them), so start researching those now. A local well drilling company can help you sift through all the requirements.