Frequently Asked Questions


How does my wastewater get into the City of Redmond’s sewer?

Your home's wastewater enters the City’s sewer main (a large pipe often running under the street) via a smaller pipe known as a lateral or side sewer that extends from your home, across your property. You are responsible for maintenance of this lateral from your home to the City's main line.

The photo on the right shows a clean 8 inch concrete wastewater pipeline without defects.

What are those City of Redmond Wastewater trucks doing in my street?

City of Redmond Wastewater Maintenance staff have implemented a preventative maintenance program involving cleaning and closed circuit television inspection of the entire wastewater system to reduce the risk of sanitary sewer overflows.                                 

Mainteance 2

Most maintenance and repair activities are conducted in City streets. The Wastewater crew utilizes flashers on their trucks, traffic cones, and reflective clothing to ensure a safe and productive work environment.

Can I plant over manholes or clean outs in my yard?
No. Manholes and cleanouts need to remain uncovered and in good working condition to allow access to the wastewater system to clear blockages, should they occur. Easement 

The retaining wall pictured on the right, must be moved to allow access to the manhole in case of an emergency like a sanitary sewer overflow.

How close to my lateral sewer pipe can I plant trees?

Depending on the species of tree, the safe distance from your lateral sewer pipe varies. Planting appropriate types of trees is of critical importance. It is unlawful to plant within thirty feet of any public or private sewer any willow, poplar, cottonwood, soft maple, gum tree, or any other tree or shrub whose roots are likely to enter and obstruct the flow of wastewater.

What causes sewer odors in my home?

If you experience sewer odors in your home, you may have a drain trap with a dry water seal. This usually occurs in the lower levels of a home in floor drains which are not used very often. Pour one gallon of water in the drain and this should rectify the odor issue.

How can I tell that I have a problem with my plumbing?

You will know you have a problem with your plumbing when fixtures do not drain; sewage backs-up into bathtubs, showers or toilets; or if sewage seeps-up from the sewer cleanout pipe next to your home.

How can I find out if there is a wastewater utility easement on my property and what activities are permitted within that area?

Call the Wastewater Division at 425-556-2827 during normal business hours: 7:00 am and 4:30 pm Monday-Friday. Staff will let you know if there is a wastewater utility easement on your property and explain what is and is not permitted within that area. Staff can also review a home improvement or landscaping project that might affect an easement.

Easement 11

Properly maintained wastewater easements allow access to manholes for routine maintenance and emergency repairs.

I have a grinder or STEP (Septic Tank Effluent Pumping) system. How do these systems work? Is there anything else I should know?

Grinder and STEP Systems are low pressure sewer systems. They consist of a control panel, pump, holding tank, and a small diameter pressurized pipe called a force main. These components are located on your property. Wastewater from your home is collected, stored, and then pumped through the force main into the City’s wastewater system.

These systems will not work if there is a power outage. The pump will not be able to empty the holding tank. Using bath and kitchen facilities during these periods may result in a sewage backup onto your property.


Where do the majority of sewer back-ups occur?

The majority of sewer back-ups are the result of a blockage in the sewer lateral which connects your home to the City's sewer main. Sewage will overflow out of the lowest sewer opening in the home (i.e., downstairs shower).

What causes a sewer to back-up?

Most sewer backups happen because the line is plugged with debris. Typical solids that build up in the pipe and cause backups are fats, oil, grease (FOG), dirt, hair, bones, sanitary products, paper towels, kitty litter, diapers, broken dishware, garbage, eggshells, coffee grounds, and concrete.

Tree roots can also cause backups. Tree roots are attracted to wastewater lines because of the waters' warm temperature and nutrients. Roots can infiltrate the pipe system and clog wastewater flow.

What should I do if I have a sewer back-up?

Call the Wastewater Maintenance staff at 425-556-2827 during business hours, or 425-556-2500 (Police) after hours and they will contact staff on-call with your information.

Wastewater Maintenance staff will assess the back-up and determine if the blockage is in the City wastewater main or your lateral sewer pipe.  The City is not able to reimburse fees incurred by customers who hire a private sewer service or plumber first and then discover the problem is caused by a City main blockage.

Will the City "unclog" my lateral sewer pipe?

Homeowners are responsible for unclogging blockages that occur in the sewer lateral located between their home and the City sewer main. The City will clear any blockage that occurs in the main in the street or utility easement.

Who do I contact if I need work performed on my lateral sewer pipe?

For your convenience, the City has a prepared list of licensed contractors able to perform work on your lateral sewer line. This list is for reference only; the City makes no recommendations as to whom you should hire to complete you work.

How can I determine where my lateral sewer pipe is located?

One of the best ways to find your lateral sewer pipe is to refer to the as-built documents you likely received when you purchased your home. If you don't have these documents, contact Development Services at 425-556-2760.

Who do I contact if a back-up in the City’s sewer main has caused damage to my property?

The Risk Management Department at 425-556-2188.

What can I do to prevent sanitary sewer back-ups?

Never flush any of the following items down your toilet: disposable diapers, sanitary napkins, bandages, rags, paper towels, pre-moistened cleaning wipes, and plastics bags. Anything that will not completely dissolve can cause a back-up.

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