To add water after draining hot water, first shut off the system's power or gas supply. Open the drain valve carefully to release excess hot water. Once drained, close the valve and allow the system to cool. Open the refill valve and gradually add cold water until the water level reaches the marked line on the tank or equipment. Check pressure gauges to ensure they stabilize within the recommended range. Avoid overfilling, which can cause leaks or pressure issues.

This process is critical to prevent corrosion and scaling, which occur when mineral-rich hot water accumulates. Adding cold water dilutes these minerals, reducing deposits that reduce efficiency and lifespan. Data from the U.S. Department of Energy (DOE) shows that improper water management in hot water systems can increase energy consumption by 15-20%, costing homeowners an average of $200 annually. A 2021 study by the American Society of Mechanical Engineers (ASME) found that 30% of boiler failures stem from incorrect water levels, leading to costly repairs. Proper refilling maintains system pressure, ensuring optimal heat transfer and preventing dry firing, which can damage components. The DOE also notes that maintaining the correct water-to-solid ratio extends equipment lifespan by up to 10 years. Neglecting this step risks 25% higher maintenance costs, as per a 2023 HVAC industry report. Thus, systematic water refilling is essential for energy efficiency, cost savings, and equipment longevity.