Abstract
The Kingdom of Saudi Arabia (KSA) is an arid country facing the challenge of renewable freshwater availability. KSA has an area of about 2.25 million km2. KSA has no perennial rivers or permanent freshwater bodies. KSA has low rainfalls with high evaporation rates which makes it very dry country. After discovering oil, KSA has witnessed remarkable economic development and rapid increase in population with migration to the urban areas in the past four decades. KSA population increased from about 4 million in 1960 to about 32.5 million in 2018. These developments lead to more pressure due to increased demand on the scarce freshwater resources. In order to meet the growing water demands, the limited renewable freshwater resources have been heavily overex-ploited. Groundwater aquifers are the main natural renewable freshwater source in the country. The average per capita municipal daily water use in KSA has been increasing since 2009 when it hit 227 L/d and recorded a gradual increase to touch 270 L/d in 2016 which is the 3rd highest in the world. Faced with increasing water scarcity and gaps between water supply and demand, policy -makers in KSA started to consider the treated wastewater as a major renewable water source and aim to achieve full utilization and reuse of treated wastewater by 2025. With a desalination capac-ity of about 2,500 million cubic meters per year which represents 30% of the world's desalination capacity, KSA is the largest seawater desalination producing country. However, desalinated water alone will not be able to supply enough freshwater to meet the increasing future water demand. However, with only 10% of the total municipal wastewater generated currently being reused, KSA is projected as the third largest reuse market after China and the USA, and reuse capacities are projected to increase by 800% by 2025. The projected growth and change in water portfolios offer tremendous opportunities to integrate novel approaches of water reclamation and reuse such as aquifer recharge and groundwater quality enhancement, district cooling and irrigation of reactional areas. Recent statistics in 2018 indicated that the volume of treated wastewater used to produce freshwater in KSA was approximately 390 million cubic meters per year. This statistic shows the revenue of the industry "sewerage " in Saudi Arabia from 2012 to 2017, with a forecast to 2024. It is projected that the revenue of sewerage in Saudi Arabia will amount to approximately 739.3 mil-lion U.S. Dollars by 2024. The KSA's treated wastewater utilization status up to date and the main key challenges facing KSA such as the substantial growth in wastewater services demand; low coverage of existing wastewater collection systems, treatment facilities, and reuse options; and the needed governmental capital investment in wastewater infrastructure development were ana-lyzed. It has been recommended that there are initiatives that should be taken thus far to tackle these challenges towards successful achievement of KSA's efficient wastewater treatment and reuse.