There is a limit to the amount of waste material that grease traps can remove from wastewater. The addition of grease, oil and solid material to kitchen wastewater must be kept to a minimum (waste minimisation). Do this by disposing of these wastes as kitchen refuse rather than down the drain. In addition to reducing pollution in your wastewater, waste minimisation benefits you by reducing grease trap cleaning requirements and preventing drain and pipe clogging within your building.

Some suggestions for reducing waste quantities in kitchen wastewater follow. Consider adopting some or all of these as standard kitchen practice. Think about ways to minimise waste that will work at your restaurant. Waste minimisation will be successful if kitchen staff understand why it is necessary and are encouraged to participate; they may have some good ideas too.

• Scrape dirty serving dishes and cooking utensils into a garbage bin before washing.
  
  
• Dispose of floor sweepings and food scraps to a garbage bin before washing floors and food preparation surfaces.
  
  
• Use metal strainers or baskets in all drains. If this slows things down, keep two strainers on hand; quickly place one over the drain while the other is emptied.
  
  
• NEVER pour waste cooking oil down a drain or toilet. Waste oil and grease should be poured into a storage container which is discarded with other solid kitchen waste. Used paint cans, large food tins or other food supply containers can be used.
  
  
• Take care not to discharge excessive quantities of detergent and/or hot water as these are also considered to be pollutants.

It is damaging to both the public drainage system and the environment to prepare food or wash dishes in laneways behind restaurants.

It is illegal to dump wastewater or waste food into gulleys and drains in the street. These drains are meant to carry rainwater. If clogged with grease and other waste the result is rats, cockroaches and overflows. During heavy rain storms, serious flooding with damage to life and property can occur if stormwater drains are clogged with waste.