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NEW OSS Documents Online

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Homeowner Certification Training

The Whatcom County Code allows homeowners who become certified to complete evaluations of their on-site sewage systems (OSS), except for the following:

  1. Proprietary OSS technologies, i.e. aerobic treatment units (ATU’s), Biofilters, Drip irrigation;
  2. Community drainfields, i.e. an OSS that serves more than one residence;
  3. OSS that have been repaired and were considered non-conforming at the time of permit issuance due to the site conditions;
  4. OSS that are serving food service establishments;
  5. Evaluations for the purposes of property transfers.

Property owners are not eligible to evaluate their OSS when a property is offered for sale.  A Licensed Operation and Maintenance Specialist must be hired to perform these evaluations. 
All gravity, non-pressurized mound (gravity mound), pressure distribution, pressure mound, and sand filter OSS may be evaluated by homeowners.  To determine your system type, refer to your OSS permit if you have a copy.  The system type is usually noted on the front page. 

If there is no permit available for your OSS, it is most likely a gravity system.  Health Department documents related to On-site Sewage Systems (OSS) and Drinking Water in Whatcom County can now be found online:

To search for the documents, you must enter the property’s Property ID, which can be obtained from the Whatcom County Assessor/Treasurer Property Search website:

The Property Search website allows for searching via the Geographic ID (aka “Parcel Number”), Property Address, or Owner Name.

Please contact us at if you have difficulty accessing the documents.

Homeowner Online Training
We have developed the following Homeowner Online Septic Training (HOST) materials to facilitate online homeowner training and certification to evaluate your own OSS.  Please follow the steps listed below to complete the process.

After completion of your evaluation, please submit the HROSS form and your certificate of completion to the Whatcom County Health Department.

For a fee of $0.15 per page, you may also obtain hard copies of the HOST study guide and HOST presentation from our office.