Jun 4 2024

Wastewater Management: Balancing Environmental Responsibility

Pressure sewers offer an alternative sanitary sewer option because they provide an economic solution to challenging environmental conditions. Gravity sewers are impractical in these situations, and septic systems pose risks to the environment. Pressure sewer systems utilize a network of grinder pumps. These pumps then transports wastewater through small-diameter pipes to a collection and treatment system.

Three men installing a pressure sewer system

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Traditionally, two methods of wastewater management were widely used and still are today. In developed areas, gravity-fed sewer systems remove wastewater from homes and buildings, delivering the fluid to collection points and treatment facilities.

A gravity sewer system consists of a network of large-diameter pipes installed at a continuous downward grade. They utilize the forces of gravity to transport fluids and lift stations to move fluid to a higher elevation when it is no longer reasonable to excavate deeper.

In areas where sewer infrastructure has not been widely built out, septic sewer systems treat water and dissipate the clean fluid into the surrounding ground. This area called a leach field, requires solids and sludge to be pumped out with a vacuum truck once every three to five years. While each of these technologies has its place, they also have their challenges in a variety of applications.

Pressure sewers offer an alternative sanitary sewer option because they provide an economic solution to challenging environmental conditions. Gravity sewers are impractical, and septic systems pose risks to the environment.

Pressure sewer systems utilize a network of grinder pumps to transport wastewater through small-diameter pipes to a collection and treatment system. A grinder pump is a submersible pump designed to reduce the size of solids in wastewater to a slurry. You can then transport this slurry for treatment.

These grinder pump stations are located in the yard or basement of each home. Wastewater flows into the basin from the building’s sewer line. The basin contains a grinder pump, level sensors, valves, and discharge piping. Discharge lines tie into a central line, still small in diameter. It transports the fluid under pressure to either a collection point or a treatment facility. Pressure sewer systems can range from a handful of pumps and stations to tens of thousands of pumps and stations, making them very flexible.

When planning new construction, one must consider environmental impact, infrastructure accessibility, cost, and future development.

Both gravity and septic sewer systems require major excavation for installation. With gravity-fed systems, large-diameter pipes must be accurately installed along a continuous downward grade to keep fluid moving at a high enough velocity. This prevents solids from settling in the line. When lines become too deep for reasonable excavation, lift stations are installed to transport fluid to a higher point of elevation.

Meanwhile, a septic tank installed underground has a capacity of at least 4,600 liters, with a leach field of at least 74.3 square meters.

Since pressure sewer systems are not limited by gravity, wastewater is pumped through small-diameter pipes that follow the contour of the land. These systems use directional boring to install piping in shallow trenches situated just below the frost line. This allows for a minimal installation footprint and expedited environmental recovery.

With a pressure sewer system, wastewater can be transported several thousand meters and can be discharged at a point of higher elevation. As a result, the need for lift stations can be minimized or eliminated in almost every installation. Since directional boring eliminates the need for large trenches, it is possible to install pipes under existing infrastructure such as roads.

This simplifies installation or restoration efforts and costs compared to gravity systems, where existing infrastructure would need to be removed and replaced.

As a closed system, pressure sewers are also protected from risks of leaking, which can contaminate lakes, streams, and oceans. A significant concern for failing septic install bases is the potential for contaminating groundwater with bacteria such as E. Coli. This contamination could be catastrophic for drinking water supplies or could pollute surrounding water in lakeside and ocean-front locations.


For some, accessible wastewater management services mean physically being capable of receiving service. For others, accessible wastewater management services mean having services that a community can afford to maintain and operate. Pressure sewers can help to address both these accessibility concerns.

Since pressure sewer systems can travel long distances and operate in all terrain types, they provide the perfect solution for unique site challenges that builders face with traditional gravity systems. Normally hard-to-service locations include settings that are rocky, hilly, have high water tables, or have long stretches of flat terrain. Gravity-fed sewer systems typically cannot serve these installation locations due to the network of large-diameter sloping pipes required.

New developments are not the only places that deserve access to wastewater management infrastructure. Many small rural communities across Canada do not have the capital to invest in new or improved gravity sewer systems, which are expensive.

A typical lift station includes a wet well, screens or grinders for solids, pumps or compressors, valves, power supply systems, alarm and control systems, odor control, and ventilation systems. The upfront cost to install a new lift station is typically at least $100,000. This overlooks the additional maintenance and operational costs that the system will incur over its lifespan. Some small communities simply cannot afford these costs.

For many of these small rural communities, septic systems are prevalent. However, septic tanks often only have a life of about 30 years, and replacement of a septic tank and leach field is also very costly. Pressure sewer systems are a solution for septic abatement projects due to low costs, quick installations, minimal environmental disruption and restoration, and easy maintenance and operation. These systems have an average maintenance interval of 10 years.

Grinder pumps are typically designed to require fewer tools and equipment for troubleshooting and repair compared to the solids handling or chopper pumps found in lift stations. Compared to lift stations, pressure sewer systems do not require the same level of preventative maintenance and inspections.

Pressure sewer systems typically use one common pump design in the entire project, simplifying service and allowingsafety inventoryof repair pumps for instances of pump failure. This allows municipalities to save on both operational and maintenance costs.

The further benefit of pressure sewer systems is allowing developers to defer their upfront installation costs. Rather than installing a costly lift station well in advance of new construction, contractors can simply install the low-pressure sewer pipe up front, and defer the cost of the grinder pump station until the sale of the home. Theoretically, the sewage system can be commissioned the day the new owner takes possession of a home.

Finally, pressure sewer systems help with load management in treatment plants. Septic sewer systems must be pumped out. Trucks bring the waste to a treatment facility, creating an increased treatment load.

Furthermore, in-flow and infiltration are common issues in gravity sewer systems because they are open to the environment. This drives up cost and inefficiency, as the treatment plant is taking on additional load by treating non-wastewater fluids.

Wastewater treatment plants for pressure sewer systems are less costly to build because the system is closed to infiltration and sizes of solids are minimized. Grinder pumps simplify the treatment process because the wastewater is already ground into a slurry, so solids are eliminated before reaching the plant.

From the homeowner’s perspective, a grinder station on their property includes storage capacity for one or two days in instances of power failure and will add only about two dollars per month to an electric bill.


Pressure sewers are a unique solution because they can be used in new applications and areas without existing infrastructure. They can also tie into existing sewer infrastructure. This helps “future-proof” areas prone to continued population growth.

Rather than expanding a gravity sewer system and undertaking a large-scale project that may require significant road construction, the new development can utilize a pressure sewer network and tie that into the existing gravity sewer infrastructure.

The ability to continue to tie into existing systems also means that pressure sewer infrastructure can be built out in phases. Large development projects can take several years to complete construction. If using a gravity sewer system, the complete build-out of sewer infrastructure must be completed before home construction begins. With pressure sewers, large developments can be broken into many phases that ultimately tie together. This allows a developer to defer costs on longer-term build-out until they have received revenue from earlier phases.


The article was first published in ES&E Magazine’s June 2023 issue.