Final answer:
Large cities typically draw water from rivers and lakes. When these sources are insufficient, alternative methods such as deep wells or desalination of seawater are used based on geographical and economic factors.
Step-by-step explanation:
Most large cities obtain water for households and industries primarily from surface sources such as rivers and lakes. While other methods like using pumps connected to springs, and deep wells, and removing salt from seawater through desalinization are practiced, these methods are more common in areas where surface water sources aren't readily available or are insufficient to meet the demand.
For instance, the historically significant city of Rome initially received water from the Tiber River, local springs, and wells. However, as the population increased and these sources became insufficient and polluted, they developed aqueducts to transport water from distant sources. Today, advanced methods like reverse osmosis are used to desalinate seawater in regions with limited freshwater sources, such as in the Middle East and parts of California.
In wealthier nations, there are more resources available to develop complex water supply systems, while in poorer countries, people often rely on more immediate sources such as wells and local rivers.