Final answer:
Running the washing machine when it's half full is wasteful in terms of water conservation as it leads to unnecessary water usage. Strategies like repairing leaks, using low-flow showerheads, and turning off the tap while brushing teeth are effective at reducing water consumption.
Step-by-step explanation:
When considering actions that conserve water, it's essential to recognize the impact of household appliances and personal habits on water usage. Among the options provided, running the washing machine only when it's half full stands out as wasteful. This practice doesn't maximize the potential of the machine per load, leading to more frequent washes and, therefore, excessive water consumption.
In contrast, repairing leaks, using low-flow showerheads, and turning off the water when brushing teeth are all effective strategies for conserving water. Repairing leaks prevents ongoing water loss that can cumulatively lead to a significant waste. Low-flow showerheads reduce the flow rate, hence using less water during showers. Similarly, turning off the tap while brushing your teeth can save gallons of water over time that would otherwise go down the drain unused. These small but cumulative actions can significantly reduce indoor water use and contribute to sustainable water management.