On-Site Sewage System (OSS) Program
The On-site Sewage System Program has regulatory oversight for
all on-site sewage systems in Whatcom County. We perform a wide
variety of activities to carry out this oversight that include:
- Site Application review for new, repaired or expanded OSS
- Permit Issuance
- Final Construction inspections
- Subdivision, Boundary Line Adjustment and Conditional Use
- Complaint investigations
- Enforcement of OSS Codes, e.g. Whatcom
County Code, WCC 24.05 and Washington
Administrative Code, WAC 246-272A
- Survey inspections of OSS in sensitive areas
- Homeowner education and notification regarding proper Operation
and Maintenance of their OSS
- Certification program for OSS Pumpers, Installers and Operation
and Maintenance Specialists
Frequently Asked Questions
Should I use an additive in my septic tank?
Most additives do not have any positive effect on your septic
tank. Nothing you add to your tank will improve normal bacterial
When is an OSS Permit needed?
An OSS Permit is needed anytime you construct, repair,
replace, modify, connect to, or expand your OSS. An OSS is
not required if you replace a baffle in a septic tank,
fix a broken house sewer pipe, replace a pump control float,
fix or replace risers, lids, or inspections ports, or replace
Can I design my own OSS?
State and County Sewage Control Regulations require that either
a Licensed OSS Designer or Registered
Professional Engineer design your OSS. The State issues Licenses
for Designers and Engineers. See Washington State Department of
Licensing at http://www.dol.wa.gov/business/checkstatus.html
Can I install my own OSS after I obtain an OSS Permit?
Whatcom County code requires that all OSS be installed
by a Licensed OSS installer; however, if you are the property
owner and you will live in the home the OSS
will serve, you can request an exemption from certification
requirements. The request will be reviewed and, if approved,
you can install the OSS. We recommend that you hire
a Licensed OSS Installer for complex systems, e.g. pressure
systems or alternative systems. See the list
of licensed installers. Developers must hire a Licensed
OSS Installer, or obtain an OSS Installer's License through
the Health Department, to install OSS on properties they plan
to develop and then sell.
Do you have a copy of my OSS permit?
Health Department documents related to On-site Sewage Systems (OSS) and Drinking Water in Whatcom County can now be found online: http://documents.whatcomcounty.us/weblink8/CustomSearch.aspx?SearchName=OSSSearch
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 Health_EH_Parcel@whatcomcounty.us if you have difficulty accessing the documents.
How do I clean up sewage that has backed up into my house?
Please see the following guidelines from the Washington State Department of Health - Sewage Clean-up.
What are some signs that my OSS is failing?
Some warning signs of a failure are:
- Odors, surfacing sewage, soggy spots with lush green grass
growth in the drainfield or septic tank area.
- Plumbing or septic tank backups
- Slow draining fixtures
- Gurgling sounds in the plumbing system
If you suspect that your OSS is failing, contact Environmental
Health for assistance.
How can I find my septic tank?
If you have an "as-built", locating the septic tank will be
easy. If one is not available you or your pumper will need to
use some investigative skills. If a crawl space is available you
may determine where the plumbing leaves the foundation wall, then
use a probe bar to find the tank. Fiberglass or polyethylene tanks
can be ruptured with a probe bar, so use caution. Probing works
best if the tank is not more than 1 to 2 feet under the surface.
If a crawl space is not available, you can sometimes use the
plumbing vents located in the roof. A plumbing vent may align
with the exit point of the sewer line leading to the septic tank.
If these options don't work it may be necessary to use an electronic
detection device with a transmitter that can be flushed down the
What is the "reserve area"?
The reserve area is designated on your OSS Permit and is another
area approved for the installation of a new drainfield in case
the main drainfield fails. The reserve are must be kept clear
of impermeable surfaces, e.g. buildings and pavement. If your
OSS Permit was issued more than 5 years ago, you may need to have
your reserve area redesigned to meet current code requirements.
Contact Environmental Health for further information.
Environmental Health Division
On-site Sewage System Program
509 Girard Street
Bellingham WA 98225
Phone: (360) 676-6724
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