Pretreatment Program for Businesses & Industry

The wastewater discharged by industries or commercial facilities can be more challenging to treat than residential wastewater. It can be contaminated by harmful or toxic substances that can’t be removed by the normal wastewater treatment process. Wastewater from industrial processes can contain copper, lead, mercury, nickel and other heavy metals and organic pollutants. Food processors can contribute high concentrations of sugar and other food byproducts that can upset the balance of the  wastewater treatment process.

To protect the treatment plant and water quality, NapaSan implements a Pretreatment Program. This program monitors industrial dischargers and requires them to use proven pollution control techniques to remove pollutants from their wastewater BEFORE discharging it to the sewer system. This practice is known as “pretreatment”.

NapaSan’s Pretreatment Program has four tactics:

Pollution Prevention:

Pollution prevention materials provided by NapaSan educate all sewer users (residential & commercial) about ways to reduce pollution in their wastewater.

Best Management Practices:

Best Management Practices (BMPs) for specific industries/businesses contain proven practices for reducing pollution in wastewater. Some BMPs are mandatory, while others are recommended.


 Some industries must receive a permit from NapaSan in order to discharge their wastewater. The permit contains pretreatment and water quality monitoring requirements. All dischargers are subject to NapaSan's local limits, which set maximum concentrations for certain constituents in wastewater discharges. Local limits are established by NapaSan’s National Pollutant Discharge Elimination System (NPDES) Permit, which is issued by the San Francisco Bay Regional Water Quality Control Board.


NapaSan inspectors visit certain types of businesses on a regular basis to ensure that pollution prevention BMPs are being implemented and to provide information.