Problems such as water scarcity and pollution frequently occur in coastal zones. This study investigated the grey water footprint and the sustainability and intensity of grey water footprint in Yantai between 2014 and 2019 by taking both surface water and groundwater into consideration. The research results indicated that the Yantai grey water footprint firstly increased and then decreased between 2014 and 2019. The lowest grey water footprint in 2019 was 744 million m³. The agricultural grey water footprint accounted for a large proportion of the total grey water footprint. Although the sustainability of grey water footprint fluctuates in Yantai, it maintains well. The Yantai grey footprint intensity gradually decreased to <10 m³/10,000 CNY. The economic benefit of grey water footprint and utilization efficiency of water resources have been improved yearly. The quality of the water environment in Yantai has also been improved. The research of this paper provides some useful information for water resources protection and sustainable utilization in coastal cities.

As the central city of the Yellow River Delta, Dongying faces challenges of water scarcity and water pollution. Based on the grey water footprint theory, the paper conducted grey water footprint accounting, factor analysis, and evaluation in Dongying from 2011 to 2023, aiming to clarify the water resources situation. Results indicated that the total grey water footprint in Dongying have decreased from 1.19 billion m³ in 2011 to 235 million m³ in 2023, a reduction of 80.21%. The agricultural, industrial, and domestic grey water footprints decreased by 94 million m³, 88 million m³, and 769 million m³, respectively, with the reduction rates reaching 54.19%, 69.98%, and 86.77%, respectively. The domestic grey water footprint has a significant impact on the dynamics of the total regional grey water footprint. The technical factor, as a negative driving factor, significantly affect the total grey water footprint in Dongying. Economic and population factors, as positive driving factors, have little impact. The water pollution level has been below 100% in recent years, with the grey water footprint sustainability remaining well. The grey water footprint intensity has decreased by 58.00 m³/10,000 CNY, a reduction of 90.60%, indicating significant improvements in water resource utilization efficiency and economic benefits. The paper provides a basis for water resource protection and water environment improvement in the Yellow River Delta region.