Which of the following is essential for ensuring pool water safety?

Regular water testing is essential for ensuring pool water safety because it helps monitor and maintain water quality. This practice includes checking key parameters such as pH levels, chlorine concentration, alkalinity, and the presence of contaminants. Consistent testing allows pool operators to make necessary adjustments, ensuring that the water remains safe for swimming and free from harmful pathogens that could lead to health risks. By understanding and managing these variables effectively, pool operators can prevent issues like algae growth, waterborne illnesses, and other safety hazards associated with poor water quality.

While options like using decorative tiles, increasing pool depth, or restricting access to adults may have their own merits, they do not directly contribute to water safety in the same fundamental way that regular testing does.