Wastewater / Septic Basics

Wastewater treatment facility The Metro Water District has 303 wastewater treatment facilities of which 92 are publicly-owned (municipal) based on facilities in operation at the end of 2006.  The total available permitted capacity for these facilities is 660 MGD, of which almost 653 MGD is permitted to publicly-owned facilities and almost 8 MGD is permitted to to private facilities.

Of the 211 private wastewater facilities located in the District, 30 are owned by public school systems, 98 are owned by industries, and the remaining 83 are owned by campgrounds, mobile home parks and residential developments.  The majority (91%) of publicly owned treatment facilities have advanced levels of treatment, and regularly produce effluent of higher quality than required by their permits. Treatment standards vary throughout the District depending upon site-specific conditions and the end-use of the returned flow.

US EPA has developed an overview of Wastewater Treatment Technologies. View EPA’s “Primer for Municipal Wastewater Treatment Systems”. (PDF)

Approximately one-fifth of residential wastewater generated in the District is currently treated by septic systems.  The percentage of wastewater treated by septic systems is expected to decline as population density increases and more sanitary sewer service is made available.

The Wastewater Management Plan provides for continued emphasis on planning, management and maintenance of septic systems, both for single family homes and for larger systems that serve more than one property. These requirements include identification of future sewered and unsewered areas, identification of septic system critical areas where their use may not be appropriate, development of a plan for the disposal of septage collected by on-site systems and adoption of a local ordinance to manage the use of private decentralized wastewater systems.

Septic tank illustration

For additional information regarding the use of septic systems in the Metro Water District please refer to the Septic Systems Status and Issues Working Paper (March 2006).

The Septic Report developed by the District in March 2006 contains descriptions of different types of septic systems.

 Wastewater Acronyms

  • CMMS = Computerized Maintenance Management System
  • CMOM = Capacity, Management, Operations and Maintenance
  • CSO = Combined Sewer Overflow
  • I / I = Infiltration and Inflow
  • LAS = Land Application System
  • MGD = Million Gallons Per Day
  • MMF = Maximum Monthly Flow
  • NPDES = National Pollutant Discharge Elimination System
  • SSO = Sanitary Sewer Overflow
  • TMDL = Total Maximum Daily Load
  • WLA = Waste Load Allocation
  • WPCP = Water Pollution Control Plant
  • WRC = Water Reclamation Center
  • WRF = Water Reclamation Facility

WWTP = Wastewater Treatment Plant