Public Works Engineering

400 W. Gowe St., Kent, WA 98032

Office Hours: Monday - Friday 8 a.m. to 5 p.m.

Phone: 253-856-5500

Fax: 253-856-6500

Private Drainage

Press Enter to show all options, press Tab go to next option

Managing stormwater on your property will...

  • Stormwater Drain Catch Basin Open GrateProtect your property investment
  • Minimize and/or eliminate flooding
  • Prevent high-cost damage and/or repairs
  • Increase safety and decrease liability
  • Improve site aesthetics 
  • Reduce the amount of pollution coming from your site that negatively impacts waterways and water quality

Flooding in BackyardBackyard flooding?

Try answering these two questions to figure out what may be occurring and how to fix it:

1.  How does rain flow off of your property?

(basically, how is the water supposed to go away)

2.  Do you have yard drains or pipes that may be blocked or need cleaning?

(pipes and yard drains are usually connected to roof downspouts and building  foundation drains)

Property owners are expected to review legal real estate documents to be aware of ownership, responsibilities, and restrictions regarding drainage utilities.

Owners of private drainage systems are expected to regularly inspect and maintain those systems when necessary. 

City Staff are available to provide some technical guidance to you for private drainage, but the City is unable to resolve issues on private property that are solely private. 

Inspect Your Drainage System Regularly!


  • For your own benefit and because you're required to! Your stormwater drainage system is your property and you want to make sure it is working properly to protect you from flooding.
    • Kent City Code 7.05, Storm and Surface Water Utility, requires all storm and surface water to be controlled in a manner that eliminates potential or existing flooding and water pollution.
    • We recommend annual inspections, or even better, twice a year - once in the wet season and once in the dry season.
    • Check your Stormwater Facility Maintenance Covenant to make sure you are meeting your required inspection frequency, which is usually at least once a year.

How to Perform an Inspection:

1. Safety first! 

  • Use the buddy system. Perform the inspection with at least one other person.
  • Do not enter any underground structure unless two or more inspectors have a confined space entry certification and fall protection equipment setup. Instead, use a flashlight, a mirror, and a probe stick.
  • Consider traffic. If you are in the road or curb-line, make yourself visible, and set up traffic control devices such as cones if needed.
  • Consider the weather. Inspecting in heavy rain, snow, or in icy conditions is NOT recommended.
  • Use personal protective equipment (P.P.E.) such as:
    • A cell phone or other way to call for help in an emergency
    • Gloves
    • Work boots or sturdy shoes
    • Flashlight or headlamp

2. Have a storm system site plan map

  • If you don't have one, get one! The only way to know what's going on... is to know what's going on. You may have to create if from scratch but contact the City first to find out what the City may have on file such as development plan as-built drawings.
  • Your site plan map will help you find all of the parts of your storm system to make sure your inspecting and operating and maintaining all of them.
  • Your site plan map should tell you what storm structures, facilities, storm lines, inputs, and outputs you have in your system, and where they are located.
  • Verify the site plan map is correct. If it is not, work to correct it for your own needs, and pass the information on to anyone else, including the City, who may benefit from the information.

3. Complete the physical inspection of your storm system

  • Using your site plan map, find all the parts (such as catch basins, control structures, ponds, bioswales, etc...) of your storm system and assess each structure's status using established maintenance standards as your guide.


  • Look at the outside and the inside of structures:
    • The lids on structures are very heavy and often difficult to remove, the City recommends hiring a licensed and bonded contractor with the correct training, tools, and equipment to help you with your inspection (and they may be able to perform any needed maintenance at the same time). For structures with grated lids, if you are able to see well enough inside without removing the lid, that's great!
    • Use a probe of some type (such as a long stick) to assess the amount of sediment collected in the sump. For really deep structures, we suggest using a flashlight to help determine need for sediment removal.
    • Use a flashlight (along with a mirror works best) to assess the walls and pipes.
  • In depth storm sewer pipe assessments will only be possible using a scope; however, looking up/down the visible ends of inlet and outlet pipes will often provide some indication of the pipe's status and need for maintenance.

4. Keep records 

  • Document your inspections on paper or electronically. This will help you keep a history of the status and maintenance needs for each part of your storm system. This history will be helpful to you and future property owners.

5. Create and follow an inspection and maintenance plan

  • Create a long-term inspection plan as a routine to follow. This is a great addition to a spring cleaning list. Then any needed maintenance that is identified can be performed during the summer and in preparation for the following winter rains.
  • Create a long-term maintenance plan to allow for budgeting. Since maintenance costs time and money, it is good to prepare and be ready for expected expenses.    

Stormwater Facility Maintenance Covenants

 A stormwater facility maintenance covenant is a binding legal document as a contractual agreement to ensure property owners adequately operate and maintain private stormwater facilities.

Covenants usually include the following requirements: 

  • Regular inspection of facilities
  • Maintenance of facilities
  • Compliance with Kent Surface Water Design Manual
  • Compliance with Kent City Code
  • Pollution Prevention
  • Access for City staff to inspect facilities

Click here to see a sample Stormwater Facility Maintenance Covenant

Wondering if your property has a covenant? Check with the King County Recorder's Office.

Implement Stormwater Best Management Practices (BMPs) to prevent flooding, erosion, and pollution in and around your home 


Prevent pollution at the source through planning and good housekeeping

 Stop or reduce erosion through collection, dispersion, and/or infiltration of stormwater runoff

Remove (treat) pollutants in stormwater runoff to improve water quality

Some helpful BMP links: 

Resources for Services and Products

  • Angie's List (to find a contractor to hire for professional assistance)

Local stores that carry typical small-scale drainage system products and supplies:

  • Home Depot - 26120 104th Avenue SE, Kent, WA 98031
  • Lowe's - 24050 Pacific Highway South, Kent, WA 98032, Store #2561