Septic System vs. Public Sewer Home Value Impact

Updated 10/2024.

When we think about buying a home, our immediate thoughts usually lead to curb appeal, square footage, number of rooms, lot size, and a long list of other wants and needs to meet our individual tastes and lifestyles. We even give thought to structural integrity—like the age and quality of the roof and condition of the foundation—as well as HVAC systems, when thinking about energy efficiency. Another not so fun or exciting, but essential, facet of home ownership is knowing about a home’s private septic or public sewage system.

If your home or the one you want to buy is within city limits, chances are you’re on a public sewer system (not always). On the other hand, homes in more rural areas are usually on septic systems. The reason: it can be costly to run enough pipe to connect a rural property to a city sewage system.

Most homes within city limits are connected to a public sewer system (but not all). Of course, most homes in rural areas are on septic. Occasionally, the local government might force a homeowner to connect to their public sewer system and decommission their septic system (because they are laying new sewer lines in the area, or simply enforcing a new policy). Also, home buyers should pay attention to whether or not a home is on a public sewer or septic system as it affects the current and future value of the home.

What are some other differences between the two systems, and does one add more value to your home than the other?

Read on. We have answers.

Do Homes Sell for More with a Septic or Public Sewer?

To answer this question we looked at all the detached homes that sold in Clackamas County and Washington County, Oregon. Why these two counties? These are two of the three counties that make up the greater Portland metro tri-county area, and both have a solid mix of rural and suburban style homes.

2022 Sewer vs. Septic Home Value Report

Criteria: detached homes on lots under .46 acre from Jan. 1st to May 1st 2022.

Washington County

In Washington County, 12 detached homes sold on less than .46-acre lots on septic systems from January 1 to May 1. These homes sold for an average of $342 per sq. ft. and sold in an average of 12 days on market.

In comparison, 1,756 detached homes in Washington County sold on less than .46-acre lots on public sewer from January 1 to May 1. These homes sold for an average of $313 per sq. ft. and sold in an average of 15 days on the market.

Clackamas County

In Clackamas County 44 detached homes sold on less than .46-acre lots on septic systems from January 1 to May 1. These homes sold for an average of $404 per sq. ft. and averaged 16 days on market.

In comparison, 1,361 detached homes in Clackamas County sold on less than .46-acre lots on public sewer systems from January 1 to May 1. These homes sold for an average of $308 per sq. ft. and took an average of 25 days on market to sell.

2022 Septic vs Sewer Results: Homes on Septic Sell for 17% More per Sq. Ft. and Sell 30% Faster than on Public Sewer

If you were thinking that switching to public sewer from your current septic system would increase your home value, think again. Overall, septic systems are cheaper to own and maintain, and certainly, we can see from this report that home buyers have no hesitation in purchasing a home on a septic system within a greater metro area.

2023 Sewer vs. Septic Home Value Report

Updated criteria. We are looking at all detached homes that sold in Multnomah, Clackamas, and Washington County from 01/01/2023 to 06/30/2023, the first half of the year. We are only looking at homes that are on lot sizes ranging from 0.46 acre to 3 acres and priced between 300,000 and 1,000,000. Why? When we look at homes in this particular lot range within a county, we get a relatively balanced number (as close as we can get) of homes on septic or on public sewer. Also, when we apply that price range we cut out extreme fixers and luxury homes to get a better baseline for the majority of homes sold in the same area.

Multnomah County showed the greatest difference. Homes on septic systems sold for 10% more per sq. ft. and 18% faster. Homes on septic also performed better across the board in Clackamas County. Interestingly, homes on public performed better in Washington County. I have a few guesses as to why that is, but it will be interesting to keep a watch on the trend.

2023 Septic vs Sewer Results: Homes on Septic Sell for 7% More per Sq. Ft. and Sell 3% Faster than on Public Sewer

2024 Septic vs Sewer Home Value Report

Updated criteria. We are looking at all detached homes that sold in Clackamas and Washington County from 01/01/2024 to 06/30/2024, the first half of the year. This year we are skipping Multnomah county again because there simply weren’t enough homes sold on septic to perform a report. We are only looking at homes that are on lot sizes ranging up to 2 acres and priced between 300,000 and 1,000,000 to avoid extreme conditions (fixers and luxury). However, unlike 2023 we are looking at lots with no minimum size and up to 2 acres with detached homes on them. This is because the 2022 report showed a more dramatic difference between septic and sewer on those smaller lot sizes. When in 2023 we did a .46 acre to 3 acre range, septic still outperformed but by not as high a margin, the lot range likely having an impact. In this report we don’t want to go over 2 acres, because the more acreage you have the more the balance of the value of the home goes towards the land and not the property itself, but we are also interested in the difference between sewer and septic on smaller lots and so are not including a minimum lot size.

2024 Septic vs Sewer Results: Homes on Septic Sell for 7% More per Sq. Ft. and Sell 12% Slower than on Public Sewer.

THE RESULTS SO FAR

We’ll keep running this report. One consistent trend so far is that homes on septic systems are consisting selling for more per sq. ft. than homes on public sewer. Days on market has been up and down and we may find that public sewer vs. septic doesn’t have a big effect on that over time.

What’s the Difference Between a Septic System and a Sewer System?

While there are a few differences between septic systems and sewer systems, the fundamental difference is what happens to waste after you flush. With a septic system, everything is emptied to an underground holding tank in your yard. Solids are separated from the liquids, and the liquids are filtered into the soil. The holding tank is emptied by a professional service three to five times a year. With sewer systems, waste is piped directly to a local water treatment plant for processing.

What are Some Common Septic Systems in Oregon?

There are several types of septic systems, and choosing the best one, depends on factors like soil type, household size, location, and more. Here’s a closer look at how they differ.

Gravity System

Sometimes called a gravity fed system, a gravity system is the more conventional septic system type, comprised of three parts: the tank, the drainfield, and the soil under the drainfield. As you might guess, gravity does all the work, rather than technology, as with a pump.

Solid waste and dark water are sent to the tank where they separate into three layers: scum, effluent, and sludge. The system then extracts the watery effluent layer, which flows to a distribution box for equal distribution to drainfield pipes. The drainfield gets treated by the soil, whereas the scum and sludge layers are treated by natural, good bacteria in the tank. Regular pumping by a qualified technician is required on an as-needed basis, or three to five times a year.

Gravity septic systems can be used in a variety of situations and areas.

Advantages of a Gravity Septic System

• Easy to service
• Affordable

Disadvantages of a Gravity Septic System

• Ground disruptions from vehicles and earthquakes can shift drainfield soil
• Requires a good slope for gravity to do its job
• Requires a minimum of 3 feet of soil under the drainfield

Mound System

Mound systems work similarly to conventional drainfields and are sometimes used as an alternative. In this case, sewage is treated with a mound of soil.

With a mound system, the drainfield sits higher than the soil’s natural surface, rather than below, and uses a gravel bed, sand fill, and a series of pressurized pipes. The entire system consists of the mound and replacement area, a tank, and a pump with a dosing pump chamber. With this type of system, after waste enters the tank, it flows to the dosing pump chamber. Floats or timers regulate the pump, and when turned on, wastewater evenly distributes into the pipes then runs through the soil and sand for treatment.

Mound system septics work best in areas with a high water table or shallow soil depth or bedrock.

Advantages of a Mound System

• Indicates the level of waste water treated before disposing of it from the sand fill
• Dosing and resting assures even distribution to the drainfield
• Wastewater travels further before joining groundwater, ensuring a better chance of purification
• Works in specific soil conditions

Disadvantage of a Mound System

• Can be hard to install and maintain
• Must remain free of trees and shrubs
• Requires a large amount of space
• Costs more than other systems

Pressure Distribution System

While many situations are suitable for gravity-reliant systems, sometimes installing a system that uses pressure to move wastewater to troughs more evenly is necessary. Components of this type of system are the tank, a dosing pump and pump changer, and a drainfield and replacement area.

This type of system works by wastewater flowing from the tank to the pump chamber, with floats and timers regulating the pump, equally distributing the wastewater. When the water gets to a certain height in the tank, this trips the pump and moves the water, then shuts off so the drainfield can absorb it. These systems also have a high water float to alert you to problems with the system, like too much water in the chamber.

Pressure distribution systems are most suitable for situations when soil depth is limited, the area is aquifer-sensitive, or the drainfield is large or sloped.

Advantages of the Pressure Distribution System

• Work well in a variety of scenarios and areas
• Usually have four dosing and resting periods per day
• Slightly less expensive than gravity systems
• Less risk of seepage

Disadvantages of the Pressure Distribution System

• Lines need flushing twice a year to clear residue buildup
• Requires electricity
• Can wind up costing more money and time due to maintenance needed

Sand Filter System

The Sand Filter System is considered supreme in the world of septic systems and requires a professional for installation. This type system consists of the tank, pump chamber, sand/gravel filter, and drainfield.

Also known as an intermittent sand filter or a recirculating sand filter, this system works much like a standard septic system. The difference is how the waste water is delivered to the soil. In this case, it filters through a layer of sand and gravel where it undergoes a three-stage process: solids are filtered out, microbes introduce nutrients to the effluent, and contaminants stick to sand grains for organic growth on top of the sand.

The sand filter system is typically used in areas with limited space or insufficient soil.

Advantages of a Sand Filter System

• Lower material cost to construct and maintain
• They are energy-efficient
• Good for areas that are environmentally sensitive or fragile
• Allow development in problematic sites
• Create high-quality effluent
• Can resolve problems with other septic systems

Disadvantages of a Sand Filter System

• More sensitive to cold, prone to freezing (can sometimes be remedied by adjusting recirculation and dosing)
• Installed and maintained by professionals, which adds to the cost

What is Cheaper to Own and Maintain, Septic or Public Sewer in Oregon?

Septic System Costs

The homeowner typically owns the full septic system and is responsible for all of its parts. Every few years the septic system will need to be pumped out, depending on the size of the tank and the number of people in the home. Annual checkups are recommended to test electrical and system components to ensure everything is working property. A homeowner can expect to spend roughly $500 a year on their septic system averaged over time. This is typically less than paying government sewer fees plus any maintenance or repairs involving a sewer line.

Public Sewer Costs

Often new home owners think there are no possible costs for the public sewer system. While it is typically true that the local government will care for the sewer line once it crosses out of your lot, any breaks, backups, or sewer line fails on your property can cost the homeowner a lot of money.

If you own or buy an older property with the original sewer lines, know that cast iron was likely used. This type of material has a life span of about 30-50 years, after which point, the lines can start to corrode and rust. Tree roots can break and and bust up the line. Replacement cost can run anywhere between $3,000 to $10,000, depending on how long they are and how deep they’re buried.

The upside to sewer systems is that they require very minimal maintenance and tend to run fine for decades at a time until they need to be replaced or have a problem. They may occasionally require hydro-flushing with water to clear blockages. This service typically doesn’t cost more than a few hundred dollars.

The main ongoing cost for public sewer lines is paying the hefty monthly government fees for the service.

Thinking of Selling your Home in the Future?

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