The City has 90 miles of sanitary sewer lines, 3000 manholes and 13 lift stations within its sanitary sewer system.

Sanitary sewer system problems are not common and the Department's maintenance procedures are intended to avoid or minimize such problems in the City's part of the system to the maximum extent possible.

The Department attempts to continually maintain its portion of the sanitary sewer system to be as trouble free as possible.

Keep Your Toilet Bowl Lid Down During Cleaning

Each year, the Public Works department cleans approximately one-third of the City's sanitary sewer lines. Cleaning begins late March, early April through October.  See map for sewer cleaning areas. In year 2017, the Purple highlighted routes will be cleaned and in 2018-Green, 2019-Blue, 2020-Orange then the cycle repeats again.  The Red highlighted routes are cleaned annually.

The sanitary sewer lines are cleaned using high performance sewer cleaning equipment. A cleaning nozzle is propelled from one manhole to the next using water under high pressure. The nozzle is then pulled back to the starting manhole. As the nozzle is pulled back, water scours the inside of the sanitary sewer pipe. Any debris in the pipe is pulled back with the water. The debris is removed from the manhole with a vacuum unit. If roots are found, they are cut with a root cutter. This process is repeated on every sewer line cleaned. Jetting (flushing sewer lines) is done once every four years.  We clean and root cut any problem areas one to two times per year.  City sewer lines requiring a higher level of maintenance are cleaned annually or semi-annually. The sanitary lift stations are checked twice weekly and include wireless monitoring and alarm equipment for flows, backups and power outages. This routine maintenance helps to prevent future blockages and back-ups and keeps our main sewer lines flowing consistently.

What to expect if you live in the cleaning area

A sanitary sewer jet-cleaning machine uses high-pressure water to clean the sanitary sewer. This high water pressure may affect your home's sanitary sewer plumbing. You may experience gurgling or bubbling water in the toilet bowl or, in rare cases, splash out of the bowl.  The water that could come from this type of incident is from the bowl itself.The common causes of air venting into homes during sanitary sewer cleaning are:  air movement from normal cleaning operations, the use of higher pressure needed when cleaning sanitary sewer lines that have a steep slope, sewer lines running close to the building, a plugged roof vent, and the size and complexity of the home’s waster and ventilation system. So, to minimize water splashing out of your toilet bowl, make it a habit to keep the lid down.  You may smell sewer gas from your basement floor drains. If this does occur, flush your toilet and pour water into your floor drains. Sanitary sewer cleaning does not damage your sewer system. The water that comes out is the water that is normally in the home's system (drain traps), not the water from the sanitary sewer in the street.

What homeowners can do to help

The sanitary sewer system begins with the plumbing fixtures inside your house.  All of the drains from the sinks, tubs, showers and toilets are piped to the sewer service that exits your house and connects to the sewer main under the street.  Each drain has a ‘trap’ and a vent pipe that prevent sewer gases and odors from entering the house.

Some basic trouble-shooting might help you when a drain backs up.  If only one section of plumbing or fixture doesn’t drain, it is usually a problem within the house.  However, if no drains work, or the entire system drains slowly, or the worst case scenario occurs – waste water comes back up through the basement floor drain, the problem is probably outside of the house in the sewer service or the sewer main. Please notify the City if a sewer cleaning service is cleaning your private sewer line so the City can make certain nothing goes into the main sewer line.

You can reduce potential problems by following some simple rules:

  • If you smell sewage but have no obvious problems, add a gallon of water to your floor drains and plumbing fixtures to insure your traps have water.
  • Never flush disposable diapers, sanitary napkins, applicators, wet-wipes, rags or other objects that might block or settle in your pipes.
  • Please do not dump gas, grease, oil, antifreeze, paint or other foreign objects down drains.
  • If using a garbage disposal, minimize amount of food and never dispose of cooking oils, greases or coffee grounds.
  • Take immediate action if you suspect your sewer line is partially plugged.


Sewer Backups

If you suspect a sewer obstruction or back up and do not know where the blockage is, contact the City of Stillwater Sewer Department before contacting a drain cleaning company.  The city will inspect the sewer main through a manhole to determine if there is a blockage in the sewer main line. If there is no problem in the sewer main, the blockage is in your sewer service pipe between the sewer main and the house. Often times root invasion from mature trees into old sewer services are causes of obstruction.


Call Public Works at 651-275-4100 Monday-Friday 7:00 a.m. to 3:30 p.m.
After hours, on weekends or holidays call the Fire Department at 651-351-4950
City crews will be dispatched to assess the situation


If it is determined that no blockage or restrictions exist in the City's sanitary sewer system, the property owner is advised to contact a professional plumber or drain cleaning service to have the private sewer service inspected. The City cannot make a recommendation for drain cleaning services. A property owner may wish to obtain several estimates.  We do however request that you notify us after a sewer service has been cleaned.  Typically, the cleaning process pushes a significant amount of solids into the sewer main and could cause a blockage in the main, which could lead to an even bigger problem.


Sewer Repairs

The property owner is responsible for any repairs on the service line from the home to, and including, the connection at the sewer main line.


Inflow and infiltration (I & I)

I & I is also a potential cause of sewer backups. I & I refers to clear water getting into the sanitary sewer system. This might occur through cracks or leaks in sewer pipes and manholes or from sump pumps incorrectly connected to the sanitary sewer system. Particularly during large rain events, I & I can cause the sanitary sewer system to overflow resulting in sewer backups. Because of the potential for I & I to create system issues, City ordinance prohibits property owners from disposing of clear water into the sanitary sewer system. This includes water from any roof, surface or ground sump pump, foundation drain, or swimming pool.


Sump Pumps

If you use a sump pump in your basement, it is illegal to drain the water into the basement sanitary sewer drain or laundry tub. Sump pumps must be discharged outside of the house to the yard or drainway that will prevent the water from draining directly to the street. Call the Public Works department if you need more information.