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Septic vs Sewer Systems: Pros & Cons of Each

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A drainage system is designed to carry sewage and wastewater away from your home or business, purify the water to remove any harmful bacteria and viruses, and then return the water back to the environment. Properly designed drainage systems help protect water quality and the health of both people and the environment.

The 2 most popular types of drainage systems are:

  1. Septic system: Transports wastewater to a buried tank that collects wastewater, removes the solids, and distributes it back into the soil.
  2. Sewer system: Transports wastewater to a municipal water treatment plant.

We’ll explain each drainage system in more detail, and go over the pros and cons for each.

At Alpha Environmental, our professionals have extensive experience working with both septic systems and sewer systems. We can diagnose the issue and repair your system, or install a new one if needed.

Septic Systems

A septic system is an on-site drainage system that uses bacteria to break down waste inside of a tank.

Septic systems have 3 major components:

  1. Main drain pipe: All plumbing fixtures drain to the main pipe, which carries wastewater from the house or building to a buried septic tank.
  2. Septic tank: Usually made of concrete, fiberglass, or polyethylene, the septic tank ecosystem has enzymes and bacteria that breaks waste down into:
    • Sludge: Heavy, dense waste that sinks to the bottom of the tank.
    • Liquid: Lighter, watery waste (also called effluent) that sits on top of the sludge. This is the waste that gets expelled back into the soil.
    • Scum: Oils and greases that float to the top of the tank and are collected in a special compartment.
  3. Drain field: A shallow excavation with downward-sloping, perforated pipes that allow the liquid inside the tank to resettle into the ground, where it’s treated and eventually becomes groundwater.

Let’s go over how a septic system works.

How Septic Systems Work

Here’s what happens with a septic system:

  1. The wastewater in your house or building flows down the drains into the septic tank.
  2. Enzymes and bacteria in the septic tank break down the waste.
  3. Special compartments prevent the sludge and scum from leaving the tank, while the effluent exits the tank into a drain field.
  4. The effluent slowly disperses into the soil through the perforated pipes in the drain field.
  5. The soil naturally treats the wastewater, removing any harmful bacteria and viruses.

We’ll go over the advantages and disadvantages of septic systems compared to sewer systems.

Advantages of Septic Systems

Septic system advantages include:

  • Economical: Installing septic systems is usually cheaper than connecting to the city’s sewer system, especially if you live in a more rural area that’s further away from the treatment plant.
  • Environmentally friendly: Since septic tanks remove bacteria before releasing water back into the soil, they don’t contaminate the water supply. Septic systems also require less energy, since they’re not pumping wastewater long distances to a treatment facility the way sewer systems do.
  • Durable: When properly installed and maintained, septic systems rarely need to be replaced. But for the system to last, you’ll need to be extra careful about what you put down the drains.
  • Independence: Since septic systems are their own contained system, they’re not affected by community sewer system issues like overflows and backups. They also encourage home and business owners to be more aware of the kind of waste thrown down the drain, since they’re financially responsible for any maintenance.

Disadvantages of Septic Systems

Septic system disadvantages include:

  • Frequent clogs: Septic systems are more prone to clogs than sewer systems, which means you have to be more careful of what you flush down the toilet and dispose of down drains. Septic tanks can’t handle some food waste and personal care products that city sewer systems can.
  • Routine maintenance: Septic tanks need to be pumped every 3–5 years and sometimes cleaned (when issues come up) to help keep them running smoothly and efficiently. A septic tank pumping involves removing the scum and liquid to improve the tank’s ecosystem. A septic tank cleaning, which essentially resets the system so it runs like new, is much more involved and also removes the sludge at the bottom of the tank.

Sewer Systems

A municipal sewer system is a network of pipes that:

  • Delivers clean, drinkable water directly to plumbing fixtures inside homes and businesses.
  • Carries wastewater from homes and businesses to water treatment plants, where the water is purified and released back into local waterways.

Sewer systems have 2 major components:

  1. Upper lateral: Often called the “main line,” this is the line closest to your home or business that includes the cleanout. It collects wastewater from all of the plumbing fixtures and carries it to the lower lateral. Since the upper lateral portion of the line sits inside the property line, the property owner is responsible for maintenance.
  2. Lower lateral: This part of the sewer line collects wastewater from the upper lateral and carries it to the city treatment plant. The lower lateral is outside of the property line, which means it’s maintained by the city.

We’ll give a brief overview of how a sewer system works.

How Sewer Systems Work

Here’s how a sewer system works:

  1. The wastewater in your house or building flows down the drains into the upper lateral line.
  2. Wastewater is carried to the lower lateral line, where it merges with wastewater from other homes and businesses.
  3. The lower lateral line carries the wastewater to the municipal treatment facility that filters and purifies the water in multiple stages.
  4. The wastewater is discharged into surface waters (lakes, rivers, coastal waters, etc.).

Let’s go over the advantages and disadvantages of sewer systems compared to septic systems.

Advantages of Sewer Systems

Sewer system advantages include:

  • Designed for heavy waterflow: Sewer systems are designed to handle heavy water usage, including water from heavy rains and wastewater from running multiple plumbing fixtures and appliances at once. A small or unmaintained septic system can easily get overwhelmed by storms or excessive water usage.
  • Minimal maintenance: While sewer systems do need regular drain cleanings, septic maintenance often involves excavation that results in a foul odor. Unless you need a repair, regular sewer system maintenance can be done without excavating.

Disadvantages of Sewer Systems

Sewer system disadvantages include:

  • Connection cost: Connecting to a municipal sewer can be expensive, especially in rural areas. Home and business owners also have to pay annual fees for using a municipal sewer system, as well as normal usage fees—similar to how you pay for water or electricity.
  • Dependent on city: If the city’s portion of the drain clogs or backs up, your home or business will be directly affected. This also means you’ll unfortunately have to wait for the city to fix the issue.

Call Us for Sewer & Septic Services in Portland, OR

At Alpha Environmental, our specialists know the ins and outs of both sewer systems and septic systems, and can answer just about any questions you have about both. Whether you need your drainage system repaired or are looking to install a new one, we can help.

Call us today at (503) 292-5346 or contact us online to schedule a free estimate for installing or repairing your drainage system.

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Lake Oswego, OR
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