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Frequently Asked Questions


  1. ​What is an On-site Sewage System (OSS)?
  2. What is a record drawing (asbuilt) & how do I obtain one?
  3. Do you have a list of licensed Maintenance Service Providers in my area?
  4. How often does my system need to be inspected?
  5. Who can perform these inspections?
  6. How often should I pump my septic tank?
  7. How do I sign up for Homeowner Septic Training (HOST)?
  8. Why did the state adopt new laws regarding on-site sewage systems?
  9. Where can I find the regulations themselves?
  10. How much will an inspection cost?
  11. How can I prevent a septic failure?
  12. I can’t afford to repair my system—now what?
  13. What is the best ground cover for my drainfield?
  14. Will additives help my system?
  15. Why is water conservation important?
  16. I’ve heard I shouldn’t use a garbage disposal. Why is that?
  17. How long do septic systems last? 
  18. I'm smelling some odors from my system.  Is this normal?


1. What is an On-site Sewage System (OSS)?

An integrated system of components, located on or nearby the property it serves, that conveys, stores, treats, and/or provides subsurface soil treatment and dispersal of sewage. It consists of a collection system, a treatment component or treatment sequence, and a soil dispersal component. An on-site sewage system may also refer to a holding tank sewage system or another system that does not have a soil dispersal component.

2. What is a record drawing (asbuilt) & how do I obtain one?

A record drawing (asbuilt) is an accurate graphic and written record of the location and features of the on-site sewage system as it was constructed. To obtain a copy go to the onlineSmartGOV Public Portal​.

3. Do you have a list of licensed Maintenance Service Providers in my area?

Maintenance Service Providers can inspect, operate, monitor, and provide maintenance to on-site sewage disposal systems. Island County Public Health has composed a list of Licensed Maintenance Service Providers, classified by specialty. For example, an Operation & Maintenance Tech may only service conventional gravity or conventional pressure systems. An Operation & Maintenance Specialist may provide service to all systems for which they hold manufacturer authorization. Go to "Hiring a Professional" to find out more information.

4. How often does my system have to be inspected?

On-site sewage systems shall be inspected in accordance with Island County Code, depending on the type of system.

  • Conventional septic systems (septic tank and drainfield only) – every 3 years

  • Conventional pressure systems (pump) – annually

  • Alternative systems (mounds, Glendons, ATUs, etc.) – annually

  • All systems will be due for an inspection at the time of sale, where the property is served by an on-site sewage system, and an inspection has not been completed within the most recent compliance period. 

​5. Who can perform these inspections?

This is dependent on the type and location of the on-site sewage system.

  • Conventional gravity systems:  A Licensed Maintenance Service Provider or a homeowner who has completed Island County’s HOST program ( free Homeowner Septic Training).

  • Conventional pressure system:  A Licensed Maintenance Service Provider or a homeowner who has completed Island County’s HOST program ( free Homeowner Septic Training)-- Unless the system is on land located within the Penn Cove or South Holmes Harbor Shellfish Protection District watersheds. Because of environmental concerns, homeowners in these “Sensitive” areas will need to hire a Licensed Maintenance Service Provider for all systems that are not conventional gravity.

  • Alternative systems:  A Licensed Maintenance Service Provider

  • Sale of home: A Licensed Maintenance Service Provider, regardless of type or location or system, if an inspection has not been performed in the most recent compliance period by the homeowner or Licensed Maintenance Service Provider.

6. How often should I pump my septic tank?

How often you need to pump depends on the size of the tank, the number of people in the household, and the amount and type of solids. Generally, a septic tank should be pumped every 3-5 years; however, some alternative systems that are more complex may need pumping more frequently.

7. How do I sign up for Homeowner Septic Training (HOST)?

Homeowners who desire to conduct their own on-site sewage system inspections must become certified through Island County and attend homeowner class(es) either in person or through our Online Training Program. Homeowner Septic Training (HOST) offers education for individuals interested in learning more about on-site sewage systems. To sign up for our HOST classes please visit our website to register. In person classes usually run from April to October while our online classes are available all year round. 

8. Why did the state adopt new laws regarding on-site sewage systems?

Washington State has significant problems with ground water pollution, which contributes to the degradation of recreational and drinking water, impacting the health of the public as well as the fishing and shellfish industries. One of the sources of pollution is thought to be high concentrations of nitrogen due to poorly functioning septic systems. The State Department of health therefore adopted more rigorous septic inspection, design, and installation standards. Having an inspection on a regular basis can prevent failures, preserve and enhance water quality, and keep shellfish areas and drinking water sources safe from contamination. Well-maintained on-site sewage systems can also save homeowners money by preventing costly repairs.

9. Where can I find the regulations regarding on-site sewage systems?

The state issued WAC 246-272A in 2005, with the intention that new septic maintenance requirements be enacted in 2007.  Local public health departments are required to enforce these regulations.

10. How much will an inspection cost?

Inspection prices vary for a few reasons. First, a person must take into account the complexity of the on-site sewage system. Second, many companies maintain their own fee schedules, which may include service calls, labor, materials, etc. Before services are performed, it might be wise to ask for an estimate or even get more than one quote.

Generally, there is no financial cost when the homeowner inspects his/her own system. If a homeowner as successfully completed Island County’s HOST program, he/she is qualified to inspect his/her own on-site sewage system, if:

  • The system is conventional gravity   

                           Or

  • The system is conventional pressure but is NOT located within the Penn Cove and South Holmes Harbor Shellfish Protection District watersheds.

​11. How can I prevent a septic failure?

Maintenance, maintenance, maintenance!! If your system has been properly designed, sited, and installed, the rest is up to you. Pump regularly, avoid excess water use, watch what you put down the drain, and be careful what you flush down the toilet.

12. I can’t afford to repair my system—now what?

Island County Public Health offers a loan program to homeowners who have failing on-site sewage systems. For more information and eligibility requirements, please contact Island County Public Health.

13. What is the best ground cover for my drainfield?

Grass is the ideal ground cover for drainfields. Grass can be ornamental, mowed in a traditional lawn, or left in an unmowed meadow. The key to planting over the drainfield is to select shallow rooted plants that require low-maintenance and low-water use.

Do not plant a garden or vegetables over a drainfield. Vegetables need watering, and excess water in the soil reduces its ability to treat wastewater. The deep roots of some vegetables may damage drainfield pipes. Bed preparation, such as rototilling or deep digging, can also damage pipes. Plus, there is the risk of contaminating food crops with sewage.

14. Will additives help my system?

Adding a stimulator or an enhancer to a septic tank to help it function or “to restore bacterial balance” is not necessary. The natural occurring bacteria needed for the septic system to work are already present in human feces. According to the U.S. Department of Health, none of these products eliminate the need for routine maintenance and pumping.

15. Why is water conservation important?

Septic tanks are essentially settling chambers. They allow time for solids and scum to separate out from wastewater, so clear liquid (effluent) can safely go to the drainfield. Over time, the scum and sludge layers get thicker, leaving less space and time for wastewater to settle before passing to the drainfield.

There are limits to the amount of water septic systems can treat. For every gallon entering the tank, one gallon is pushed out into the drainfield. In some instances, too much water may back up into your house or overload the drainfield and surface in the yard. The problem is large volumes of water may not allow solids enough time to settle and may be carried out to the drainfield, ultimately clogging the pipes.

16. I’ve heard I shouldn’t use a garbage disposal. Why is that?

Garbage disposals have a dramatic impact on pumping frequency. Food particles usually are not digested by the bacteria and accumulate as scum. If a large amount of water enters the tank, it can them push the food particles into the drainfield, causing clogging. If you must use a garbage disposal, you should get your tank pumped more frequently.

17. How long do septic systems last?

Septic systems are designed to provide long-term, effective treatment of household waste when operated and maintained properly. However, most systems that fail prematurely are due to improper maintenance. Less serious problems are usually with plumbing (such as pipe blockages from tree roots growing into the pipe). Sometimes, the septic tank, although durable, can deteriorate or have other structural problems.

The most serious problems are the result of a clogged drainfield. Unfortunately, this is the most expensive to repair. It is important to keep in mind that repair costs vary greatly by the type of maintenance needed. Minor repairs (such as adding risers to the surface) might cost as little as a few hundred dollars, while major repairs (such as replacing a clogged drainfield) can cost up to $20,000 or more to replace.​

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