Onsite insight: What everyone needs to know about onsite septic systems

Flush it and forget it, right? Not so fast if you’re one of tens of thousands of King County homes and businesses with an on-site septic system. An on-site septic system (OSS), more commonly known as a septic system, is a mini-water treatment facility right on the homeowner’s property. Designed, installed and maintained properly, an OSS can process wastewater from toilets, showers, washing machines and dishwashers without contaminating the environment. On-site systems are a great solution for homes that are too far away to hook up to a municipal sewer system.

ossOSS systems can last decades with proper maintenance. But an improperly maintained system can pollute property, surface and groundwater, lakes, streams, rivers and other bodies of water. Public Health’s role is to ensure OSS owners across the county understand their roles and responsibilities to make sure their systems are functioning properly. We talked to Public Health’s Wastewater Supervisor Lynn Schneider to learn more.

Lynn, how does a septic system work? A typical septic system consists of two components – a septic tank and a drainfield. When you flush the toilet or drain the kitchen sink, the waste goes out of the house through pipes to a water-tight septic tank. The solid material and liquids separate inside the tank. The solids are pumped out by an OSS pumper. The liquid (or effluent) is discharged into a series of pipes buried in an adjacent drainfield. These pipes have holes in them to allow the effluent to “percolate” into the soil, where it is naturally absorbed. This process naturally treats the effluent to remove coliform and other bacteria, viruses, and other contaminants, which are dangerous to health if not properly treated.

That sounds fairly straightforward – is it?
Not all soils are equally effective at absorbing and treating wastewater from a septic tank. The type of soil, the size of the drainfield, the geography of the drainfield, the water table and other factors impact the OSS design.  Septic systems can be highly complex feats of engineering, or they can be relatively simple – it all depends on the soil and other conditions of the particular property where it is installed. Not all soils can support an OSS.

What are signs of a system failure?
Overuse and improper maintenance can lead to system failure. It’s not always possible to know whether your OSS is failing, which is why routine maintenance is critical. But typical system failure signs include backed-up waste water, spongy grass on the drainfield (even during dry weather), water collecting around the drainfield, and an odor around the septic tank or drainfield. If you see (or smell) any of these signs, call a septic professional immediately.

You’ve mentioned regular OSS maintenance several times now. Why is that so important?

There are three key reasons to regularly maintain your OSS even if you have no signs of system failure:

  1. It protects your investment: Fixing or replacing a failing OSS can be very expensive – depending on your property’s size and soil features, replacement systems can cost tens of thousands of dollars. Sometimes, it’s not even possible to replace a system! Keeping your OSS functioning well protects your property value.
  2. Keeping sewage out of the environment protects the health of your family, your neighborhood, and the community. Sewage contains bacteria and viruses that can make people and animals sick from illnesses ranging from gastrointestinal problems to ear and eye infections and infectious diseases such as hepatitis. Malfunctioning OSS contaminate and degrade water quality and impact shellfish and other plants and animals. For example, on Vashon Island’s Quartermaster Harbor, failing OSS have led to a long-time closure of the recreational and commercial shellfish harvest – a loss of millions of dollars.
  3. Regular maintenance of your OSS is the law. Learn more about your legal responsibilities at the Washington State Department of Health website and the Washington Administrative Code.

What’s Public Health’s role in assuring that homeowners properly maintain their OSS?
OSS are the homeowner’s responsibility. Federal and state laws require oversight, and in King County, Title 13 of the Board of Health code requires appropriate OSS oversight by Public Health. However, Public Health is not funded to carry out its responsibilities under these laws.

Currently, Public Health’s funding allows only for program activities such as permitting new or repaired OSS systems, reviewing systems when the property changes hands, and following up on complaints. Public Health has a time-limited grant to improve conditions in Marine Recovery Areas, such as Vashon Maury Island. Public Health also licenses septic system professionals to make sure that the designer and maintainer OSS system owners hire are properly trained and prepared to provide the best possible OSS  services.

Public Health is currently working with elected officials and stakeholders to find ways to identify resources needed to ensure people’s OSS are functional and safe for all.

What is the goal for your program?
In order to be compliant with state and federal law, Public Health must determine the number of OSS in the county, identify and plan for high risk areas where pollution is likely occurring, facilitate owner education about proper maintenance, and meet other requirements.  Our goal is to develop a more complete set of services including regular oversight of OSS in areas where pollution is identified. One place to start is by developing a county wide database that includes all OSS. The reason we don’t know where all the OSS systems are is because many of these systems were put into place before permits were required.

A friend of mine didn’t even realize that their house was on a septic system. How can you tell if you don’t know?
A few signs are sure give aways: Having a well, no water meter, “$0.00 Sewer Amount Charged” on your water bill or property tax bill. And, if your neighbors are on septic, then you may well be on septic as well. Hire a septic professional to help you locate the septic tank lid.

Where can people learn more about on-site septic systems?