A conventional pollutant is a term used in the USA to describe a water pollutant that is amenable to treatment by a municipal sewage treatment

Sewage treatment

Sewage treatment, or domestic wastewater treatment, is the process of removing contaminants from wastewater and household sewage, both runoff and domestic. It includes physical, chemical, and biological processes to remove physical, chemical and biological contaminants...

 plant. A basic list of conventional pollutants is defined in the U.S. Clean Water Act

Clean Water Act

The Clean Water Act is the primary federal law in the United States governing water pollution. Commonly abbreviated as the CWA, the act established the goals of eliminating releases of high amounts of toxic substances into water, eliminating additional water pollution by 1985, and ensuring that...

. The list has been amended in regulations issued by the Environmental Protection Agency

United States Environmental Protection Agency

The U.S. Environmental Protection Agency is an agency of the federal government of the United States charged with protecting human health and the environment, by writing and enforcing regulations based on laws passed by Congress...

:

• biochemical oxygen demand
  Biochemical oxygen demand
  Biochemical oxygen demand or B.O.D. is the amount of dissolved oxygen needed by aerobic biological organisms in a body of water to break down organic material present in a given water sample at certain temperature over a specific time period. The term also refers to a chemical procedure for...
  
   (BOD)
• fecal coliform bacteria
• oil and grease
• pH
  PH
  In chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at . Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline...
  
   (exceeding regulatory limits)
• total suspended solids
  Total suspended solids
  Total suspended solids is a water quality measurement usually abbreviated TSS. It is listed as a conventional pollutant in the U.S. Clean Water Act. This parameter was at one time called non-filterable residue , a term that refers to the identical measurement: the dry-weight of particles trapped...
  
  (TSS).

The Secondary Treatment Regulation contains national discharge standards for BOD, pH and TSS, applicable to sewage treatment plants in the U.S.