Lakes and reservoirs (collectively referred to as lake-reservoirs) serve as the "power source" for the green and high-quality development of the Yangtze River Economic Belt. They also act as the "cornerstone" for ensuring the safety of drinking water in cities along the Yangtze River Economic Belt and in the Beijing-Tianjin-Hebei-Henan region. Clarifying the spatial distribution and water quality evolution of lake-reservoirs used as drinking water sources is helpful to enhance the capacity to safeguard drinking water security. This study integrates ecological and environmental statistical information to construct a dataset of prefecture-level and county-level centralized drinking water sources across 11 provinces along the Yangtze River Economic Belt. Our results show that among all 1,557 prefecture-level and county-level centralized drinking water sources in 2025, 762 water sources are lake-reservoir types accounting for 49.0%, which distributed across 23 lakes and 682 reservoirs. Over the past decade, there has been a notable increase in both the number and proportion of lake-reservoir-type drinking water sources at both prefecture-level and county-level centralized drinking water sources, which further highlights the crucial role of lakes and reservoirs in ensuring the safety of urban drinking water. Long-term Landsat satellite remote sensing estimation results indicate that since 1986, the transparency of lakes and reservoirs used as drinking water sources in the Yangtze River Economic Belt has shown a significant upward trend. Secchi disk depth of lakes and reservoirs increased from 1.41 ± 0.78 m in 1986 to 1.94 ± 1.35 m in 2024 demonstrating that the overall water bodies are becoming clearer. However, there are marked differences between lakes and reservoirs, with lake transparency declining while reservoir transparency has risen significantly. Long-term positioning monitoring of five key water quality indicators—dissolved oxygen, total nitrogen, ammonia nitrogen, total phosphorus, and biochemical oxygen demand—in 47 drinking water source lakes and reservoirs from 2005 to 2024 uncovers an overall significant improvement in water quality. The total nitrogen and total phosphorus concentrations decreased from 1.90 mg/L and 0.100 mg/L in 2005 to 1.30 mg/L and 0.052 mg/L in 2024, respectively. Nevertheless, the total nitrogen concentration in reservoirs has not shown marked improvement and has even increased in some cases. Currently, the protection, governance, and sustainable development of drinking water source lakes and reservoirs continue to face multiple risks and challenges, including excessive external pollution loadings from the catchment and increased internal pollution release, high nitrogen and phosphorus concentrations leading to blue-green algae blooms, the degradation of submerged vegetation and decline in biodiversity, as well as the increased frequency of extreme floods and droughts caused by global climate change.