Which of the following measures can significantly contribute to reducing drawdown of water from natural resources?

Reducing potable water use directly impacts the demand for water drawn from natural resources, making it a significant measure for conserving water. When less potable water is consumed, there is a lower requirement for sourcing that water, which in turn reduces pressure on aquifers, rivers, and lakes. This approach not only leads to more sustainable usage of existing water resources but also promotes the conservation of ecosystems that rely on these water bodies.

While measures such as increasing wastewater treatment and implementing rainwater harvesting are beneficial for water management, their primary influence is on the efficiency of water use or the provision of alternative water sources rather than directly reducing the total demand for potable water. Retrofitting existing buildings generally optimizes water usage within those buildings but does not necessarily affect the overall drawdown from natural resources if the complete water needs remain unchanged. Thus, reducing potable water consumption is the most direct action for minimizing the extraction from natural water systems.