The Council of Ministers issued a Royal decree number M/6 1421 H, corresponding to 2000 AD. The decree stated that, in Saudi Arabia, all wastewater should be treated at the tertiary level, without any discrimination (in terms of the type of reuse and discharge locations). The aim of this article is to discuss and elaborate the royal decree (2000AD), showing its limitations and recommending several modifications. This paper is a review and analysis of treated wastewater reuse in Kingdom of Saudi Arabia (KSA) and impact of implementation of royal decree for the treatment of wastewater reuse in future. Moreover, a critical appraisal of the use of tertiary treatment was done by elaborating negative impact of tertiary treatment and comparing a review of treatment of wastewater reuse in USA. It is emphasized in the paper that degrees of wastewater treatment should depend on: (a) types of reuses/discharges, methods of irrigation and local environmental conditions, and (b) whether irrigation takes place in restricted or unrestricted agriculture and types of crops. Thus, the Saudi Royal Decree (2000AD) that requires wastewater treatment up to a tertiary level needs to be re-evaluated and modified. The article suggested correlating the degree of wastewater treatment with the intended reuse, discharge locations and the degree of exposure to the public.