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FAQs About Waste Water Treatment

What happens to the water that goes down the toilets, drains and sinks in my house?
The waste water from our homes travels through a series of trunk sewers (underground pipes) that make up the City's sewer system, to the Water Pollution Control Plant on Atlantic Avenue. When it arrives at the main pump station at the plant, the sewage passes through bar screens where large debris is removed. From here the sewage moves to grit tanks where heavier material such as sand and gravel can settle out and be removed. Next it moves on to primary clarifiers - open tanks where sludge solids settle on the bottom and are scraped away. The liquid portion that leaves the clarifiers is called primary effluent. This effluent moves on for secondary treatment where particulate and ammonia are filtered out. Sludge is the waste generated in the process. It undergoes break-down processes and then is de-watered and hauled to the City's landfill site for final disposal. The cleaned plant effluent is discharged back into the water table.

What are some of the things that should NOT be put down the drain?
roducts that are labelled as hazardous materials should never be disposed of down the drain. Hazardous materials are labeled as corrosive, toxic, reactive or flammable. The list includes items most of us use in our homes – all-purpose cleaners, antifreeze, paint, paint thinner, pool chemicals, solvents and motor oil to name a few.

Even animal- and vegetable-derived cooking oils and grease can block drains and in some cases can even block City sewer lines.

Other items include:

  • cigarette butts Photo of kitchen sink drain
  • dental floss
  • condoms
  • rags
  • feminine sanitary products
  • diapers
  • human or pet hair
  • cotton swabs
  • cosmetics/makeup
  • food scraps
  • coffee grinds
  • pharmaceuticals
  • kitty litter

What should I do with fat or oil if it can’t go down the drain?
Oil and fat can be put in the garbage. Pour it into a container, let it cool and put it in with your regular garbage. Restaurants and other commercial food preparation locations that generate a quantity should put the grease in appropriate recycling receptacles.

What’s the difference between a sanitary sewer and a storm sewer?
The sinks, bathtub, toilets and washing machines in your home drain through your plumbing into a sanitary sewer. Floor drains can be an exception – some may drain into a storm sewer. 
Outdoor drains along the side of the street take in storm water and spring melt discharge directly into Lake Superior. Anything that goes down these drains goes straight to the lake. That is why it is so important to dispose of liquid wastes and hazardous wastes safely.

Can I take a tour of the Water Pollution Control Plant?
To arrange a tour at the WPCP or the Bare Point Water Treatment Plant, contact the Infrastructure & Operations Dispatcher at 625-2195. (This service is not available at this time, please check back for further information.)