Environmental Health

Global Menu

Environmental Health

Director: Jennifer Johnson

Septics 101 from Skagit County on Vimeo.

Skagit County on line Septics 101 Class Quiz

Fill in the contact information and complete the quiz if you want Skagit County to have a record of you having taken the Septics 101 class. This record is necessary if you wish to apply for a Rebate or wish to sign up for a Septics 201 class.

You must enter a vailid email address to receive your results.




Email address:

Mailing address:



1. Commercial septic system additives, yeast, cabbage, and raw meat do not need to be added to the septic tank to help it do the job of clarifying sewage.


2. Septic systems need to be inspected in order to keep them working a long time (30 years or more) and to assure that they are treating sewage adequately.


3. The septic tank is an aerobic environment (oxygen from air is abundant) where most of the septic system treatment occurs.


4. The drainfield needs to be an aerobic environment (oxygen from air is present) in order for sewage to be treated fully by the biomat at the bottom of the drainfield.


5. What can home occupants do to help the septic system work well?

Keep the amount of sewage produced each day to no more than the maximum amount the septic system was designed to treat.
Do a maximum of 1-2 laundry loads on any single day
Divert rainwater away from the septic tank and drainfield
Do not put harmful chemicals into the septic system
Grow only shallow rooted plants over and near the drainfield
All of the above

6. What happens in the drainfield if the air supply is cut off by compacted soil above it, paving the ground above it, or if it is flooded with water?

Sewage will back up into the house.
Sewage will not be treated fully because the biomat will be cut off from the oxygen (air) supply.
The drainfield will become an aerobic environment and the good microbes in the biomat will continue to treat sewage fully.

7. What is the primary purpose of the drainfield?

Clarify sewage before it goes into the environment..
Treat sewage to reduce the amount of bacteria and viruses as well as reduce the overall strength of sewage before it is released into the ground to become groundwater.
Reduce sewage odors and keep animals from coming into contact with the pathogenic bacteria and viruses.

8. What is the primary purpose of the septic tank?

It decreases the number of bacteria, viruses, and other pathogens in sewage.
It breaks down solids into liquids and gases.
It clarifies sewage before it goes into the drainfield

9. What will happen if the septic tank does not get pumped and fills up too much with scum and sludge solids?

The solid matter entering the tank, such as toilet paper, manure, and vegetable matter can go through the tank and plug the drain field soil.
There will be more anaerobic decomposition of solids in the septic tank.
There will be more food for the good biomat microbes in the drainfield to help them grow.

10. When is it time to call a septic tank pumping company to have the tank(s) pumped?

When the bottom of the scum layer is within 3 inches of the inlet baffle bottom opening
When the sludge has accumulated to within 12 inches of the inlet baffle bottom opening
When the sludge and scum solids make up 33% or more of the septic tank volume
All of the above

11. Which of the following is NOT a public health concern for septic systems?

Contaminating recreational and commercial shellfish beds
Contaminating groundwater
Contaminating surface water
Keeping lawns health and green over the top of the drainfield

12. Why is the Skagit County Public Health Department interested in the design and operation of each septic system in the County?

A properly designed and functioning septic system will reduce the chance that food and drinking water will become contaminated with sewage..
It is this department's job to keep sewage out of sight and out of mind.
It is this department's job to reduce neighbor disputes from failing septic systems.

13. Homeowners in Skagit County that have a conventional gravity septic system need to have their system inspected every 36 months or less.


14. Homeowners in Skagit County that have a septic system with a pump (not a conventional gravity septic system) need to have their system inspected every 12 months or less.