What are the different types of residential sewerage systems?

What homeowners should know.

There are three main types of residential sewerage systems: Gravity, Low-Pressure and Vacuum.

Using the bathroom is something we all do, but we don't usually think about how the toilet works or which residential sewer system is best.

It's important to maintain any type of residential sewer system for it to work properly. There are different types of systems with their own advantages and disadvantages, and in this article, we will explain them.

We want to let you know that we manufacture one of the types of systems we will talk about, but you can research all the options we present.

Some people may see the words "sewer system" and "sewerage system" online and wonder what the difference is. They mean the same thing, but we chose to use "sewerage" in this article to be more inclusive of our international customers.

Gravity Sewerage Systems

A gravity sewerage system is a common type of sewer system that doesn't need electricity to function, except for lift stations. However, erosion can happen over time from various causes, which can lead to sewage leaks. Heavy rain can also cause stormwater to enter sewer lines, which can cause blockages, leaks, or backups. This problem often occurs at manholes and can result in overflows when the power goes out.

When installing a gravity sewerage system, a minimum slope of 2% must be maintained. They are usually installed on roadway centerlines, which can lead to road closures due to the depth of construction and dewatering requirements. Additionally, more pavement restoration may be required.

Low-Pressure Sewerage Systems

A low-pressure sewerage system is a setup with a small tank containing a grinder pump and an alarm panel, installed in a homeowner's property. When the wastewater reaches a certain level, the grinder pump grinds the contents and sends the water through small piping to the main sewerage line. However, the homeowner is responsible for maintaining the system and providing electricity to the grinder pump.

It's important to follow guidelines to avoid putting harmful items down the drain, which can cause issues with the system.

This list of “Harmful Items” includes:

Kitty litter, coffee grinds, gravel, sand, aquarium stone
Hair clippings, coffee beans, eggshells, cigarette butts
Personal hygiene products, cleaning wipes, dental floss
Diapers, rags, cloths, Q-tips
Cooking fat or Cooking oil (lard, bacon grease), Lubricating oil, other grease
Glass, metal, wood, seafood shells
Plastic objects (toys, eating utensils, etc.), rubber or latex
Strong chemicals, toxic, caustic, or poisonous substances (this includes Drano, Mr. Plumber, etc.)
Any explosive or flammable material
Gasoline, kerosene, fuel oil, paint, paint thinner, anti-freeze
De-greasing solvents

If two families are using the same tank for their sewage, both of them should follow the rules for how to dispose of their waste. If one family doesn't follow the rules, it could cause problems for both families. So, it's important to talk and agree on a set of rules to make sure the system is used correctly.

Vacuum Sewerage Systems

A vacuum sewerage system is a good way to handle sewage when septic tanks are causing pollution or gravity sewer systems are old. They work especially well in places with sensitive eco-systems or where the ground is hard to dig in, like where the water table is high, the soil is sandy, or the rocks are difficult to move.

In a vacuum sewerage system, pumps keep the system under pressure, and valves keep the sewage in the pipes until it's time to move. When the valves open, the pressure pulls the sewage to a vacuum station.

This system has been around for a long time, but not everyone knows about it. Up to three houses can share a vacuum pit, and a monitoring system can tell the city when there's a problem.

Homeowners don't need to do anything different, and the city takes care of everything. The only power needed is at the main vacuum station, which always has a backup generator.

Installing this system is easier than other systems, and it causes less disruption to the neighborhood. Because of the constant pressure, sewage never leaks into the ground. Even if a pipe breaks, the vacuum continues to “suck in” instead of “leak out” wastewater, which is good for the environment.