12811 6th Street
Rancho Cucamonga, CA 91739
Regional Water Recycling Plant No.4 (RP-4) is located in the city of Rancho Cucamonga and has been in operation since 1997. The plant has undergone an expansion to increase the design hydraulic domestic sewage (wastewater) treatment capacity to 14 million gallons per day. The plant serves areas of Fontana, Rancho Cucamonga, and San Bernardino County. The plant treats the liquid portion of an average influent wastewater flow of approximately 10 million gallons per day.
The liquid treatment section consists of preliminary screening and grit removal, primary clarification, secondary treatment by aeration basins and clarification, tertiary treatment by filtration and disinfection,. Wastewater liquid is treated to California Department of Public Health Title 22 Code of Regulations standards for disinfected tertiary recycled water. The solids removed from RP-4 are conveyed by gravity through the regional sewer system to the influent of RP-1 for thickening, anaerobic digestion, and dewatering.