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Preventing Sewer Backups Homeowner Best Practices

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Causes of Residential Sewer Blockages - Grease Is Harmful To Sewers

VacTruckGrease sticks to the insides of sewer pipes. The buildup of grease is the main cause of sewer backups and overflows. Too often, grease enters into the sewer system by way of the kitchen sink. As it builds up along the walls of the sewers, the carrying capacity of the sewer lines decreases. Low concentrations of grease poured down drains over extended periods of time are also problems.

AWWU’s Operations & Maintenance Line Crews use a specially designed water jet truck to send high pressure water into the sewer lines. Grease and other debris are dislodged and float to a manhole where the debris is trapped and vacuumed up with a large hose on a Vactor truck.

Help prevent the discharge of improper objects into sewer mains. Backups are caused by debris, regardless how often the lines are cleaned.

Deep Frying a Turkey?

Don’t dump the oil down the drain, bring it to a Municipal Hazardous Waste Collection Facility Monday-Friday, 8am-5pm, at Anchorage Regional Landfill or Central Transfer Station, 1111 E.56th Ave. Up to 5 clean gallons in a sealed container (5-gallon bucket with lid or original containers are great choices). Free for residents. The oil is reused for heating. For more information from Solid Waste Services, visit the Anchorage Hazardous Materials Management page.

Do Not Put Fats, Oils & Grease Down Your Drain

GreaseFats, oils and grease are a big problem because they cause most sewer line blockages. Sewer blockages are not only filthy; they can be the cause of serious health hazards. Clean ups are difficult, costly and time-consuming.

Raw sewage can back up into homes and businesses, as well as flow onto streets and parking lots when sewer lines are blocked.

Fats, oils and grease include meats, sauces, gravies, salad dressings, deep-fried dishes, cookies, pastries, cheese, butter and other food products. Scrape all food scraps and solids into a garbage can instead of the sink. Do the same with gravies, salad dressings and similar liquids that contain fats, oils and grease.

Fats, oils and grease build up on the insides of pipes and on equipment. It is expensive to be removed from sewer collection systems and wastewater treatment facilities. These additional maintenance costs are passed on to you and other AWWU customers.

Help Prevent Sewer Blockages


  • Avoid drain clogs. Do not let hair build up in the shower, bath tub and wash basin drains.
  • Scrape grease and food residue from dishes and pans into the garbage before placing them in the sink or dishwasher. This will reduce grease build up in the sewer lines.
  • Unclog drains naturally. Pour ¼ cup of baking soda down the drain followed by ½ cup of white vinegar. Wait a few minutes and follow this with boiling water. Pour boiling water down the drains weekly to prevent clogs.
  • Empty washing machine lint into a garbage bag. Do not empty lint into the sink or the sewer line.
  • Associations for condominium or town homes should contract with a licensed and bonded line cleaner to perform routine preventive maintenance on sewer collector lines in the street and check all water fixtures, sinks, toilets, showers and outdoor faucets for leaks. Leaks that remain undetected and are not repaired actually help to overload the sewer collection system and may also increase water and sewer rates.

Do Not:

  • Do not pour grease of any kind down sinks, garbage disposals, or other drains. Grease is the major contributor of sewer blockages.
  • Do not flush diapers, sanitary napkins, newspapers, soiled rags, or paper towels down toilets.
  • Do not put used oil, oil-based paints, solvents or other chemicals down sewer lines, storm drains or into drainage ditches.

Other Helpful Tips

  • Recycle used oil and antifreeze. Service stations and recycling centers will take used oil and old antifreeze.
  • Call Municipal Solid Waste Services, 343-6262, for hazardous waste disposal information.
  • Always read a product’s Material Safety Data Sheet (MSDS) for proper disposal guidance.
  • Just one quart of oil has the potential to contaminate two million gallons of water!
  • Speak with your friends and neighbors about the problem of grease in the sewer system and how to keep it out.
  • Call AWWU’s Pretreatment Program for assistance, 751-2253 or 751-2219. There are fines and penalties for illegal and improper discharges.

Help prevent raw sewage overflows. Keep grease out of the sewage system.

If you have additional questions about sewer blockages and/or what can safely be put into the wastewater system, please call Anchorage Water & Wastewater Utility's Pretreatment Program, 751-2253 or 751-2219, or by email at