AbstractPlumbing planners and architects choose to use the 1940s Hunter curve that articulated domestic demand to solve the complex and multifaceted difficulties they found in the probabilistic process. This curve was designed to predict the water demand for the installation of high-performance streams operating at an almost maximized level of confidence (CL) of 99%. Many everyday things have changed for the better. At the moment, these problems are creating overestimation consequences according to Hunter’s curve. Allowing the use of modern water use appliances does not reflect the consequences of water sustentation. In the background, Hunter’s curve was modified in 2014 for a maximum of 300 fixtures. In the present study, to meet the high and optimum water demand, Hunter’s curve was remodified by up to 1,000 fixtures by incorporating low flow rates in modern flush valves to effectively reduce CLs, leading to significant water savings. The standardization of the fixture units for those operating valves has been established and is done efficiently using the binomial-probability-function for large-scale system operations, i.e., at various flow rates, low CLs, and reduced consumption. In such a case, water savings can be achieved by 80%–95% in relation to Hunter’s original adoption. The redesigned Hunter curves for optimized CLs used in the current paper focus on the excellent performance of plumbing design by improving water use and prevention.