Can a Macerator Pump Uphill? (Things to Know)

Pumping black or greywater from a toilet to a septic tank located above can be challenging. Although macerator pumps work well in Saniflo systems, pumping uphill involves going against gravity and requires additional power. This is where the confusion comes as many people want to know if macerators have sufficient power to pump uphill.

Macerators can pump uphill up to 4 meters (13.12 ft), and you must ensure that your septic tank is within this range of your toilet. Alternatively, you can provide support by installing a lift station which comes at an added cost and complications.

In the rest of this article, I’ll discuss how macerators are able to pump waste uphill. I’ll also cover the benefits of using a macerator. Keep reading!

macerator pump

How Macerators Pump Waste Uphill

Pumping waste, especially in a solid state, requires a lot of power and pressure. If the pump doesn’t have sufficient power, it must, therefore, create enough pressure to move the waste uphill.

Macerators can pump uphill as they are designed to work in the following ways:

They Convert Solid Waste Into Slurry

The term “maceration” means to break down into small pieces. Macerators, which are also known as grinding pumps, work by breaking down solid waste into a slurry state before pumping it out.

Waste from the black tank contains feces and, sometimes, accidental sanitary items like feminine hygiene products. These solid waste products are challenging to move uphill and must be broken down into smaller pieces for efficiency.

Macerator pumps are designed to break up and soften solid waste before pumping. The system has a stainless steel blade that rotates faster to break solid waste into smaller pieces.

pipe of power pump machine pouring mud sludge waste water with sand silt on ground

After cutting the waste into smaller pieces, the rotational motion mixes the pieces with the water flushed from the toilet at high speed. This combination creates a liquid slurry that’s easier to move uphill than solid waste.

Macerators Increase the Water Volume in the Tank

Macerators also increase the black tank’s water volume to support the slurry’s expulsion into the outlet hose. This also helps move the waste uphill.

The macerator pump has an intake hose that draws water from a nearby source, such as a toilet. This water is added to the black tank to increase the volume, which in turn increases the pressure required to pump uphill.

This process also helps in flushing out any remaining solid waste since more water means a more efficient flush.

Macerator Pumps Create Pressure

Water pressure alone is not enough to pump the slurry uphill. The pump needs more pressure to prevent clogging and to ensure a smooth flow.

Once the slurry starts leaving the digester, it’s directed into specially-designed outlet tubes to increase the pressure. The outlet tubes come in 3/4 to 1-inch (1.91 to 2.54-cm) diameters.

Moving slurry under pressure from a wider tube to a narrower one increases the pressure, making it easier for the pump to push the waste uphill.

hand press and flush toilet

In a nutshell, here is the maceration process:

  1. Flushing the toilet: When you flush the toilet, gravity pushes the waste through the rear spigot. The effluent discharges into the macerator chamber behind the spigot.
  1. Microswitch activation: The macerator keeps drawing in water, and as the level keeps rising, it activates the microswitch that, in turn, turns on the macerator device.
  1. Grinding the effluent: Once the macerator is activated, the blade starts rotating rapidly (3,600 revolutions per minute) to grind the effluent into tiny pieces.
  1. Slurry creation: The tiny effluent pieces mixes with the incoming water. The rotating blade facilitates the mixing, turning the pieces into a slurry that’s easier to pump. The slurry formation ends the macerating process by deactivating the micro switch.
  1. Pumping the slurry: The slurry is pumped from the macerating chamber through 3/4 to 1-inch (1.91 to 2.54-cm) diameter tubes to increase the pressure to move the waste uphill. The pressurized slurry is pumped into the sanitary gravity drain or a septic tank uphill.
  1. Back-flow prevention: Since the effluent is light and watery, it’s easy to flow back from the septic tank. However, the unit has a non-return valve that prevents backflow while pumping uphill.
  1. The toilet refills with water: After discharging the waste, the macerator draws in water to fill the toilet bowl.

Benefits of Using Macerators

Using macerator pumps is beneficial, especially when pumping uphill. Here are some of the main benefits:

  • Increased flexibility in toilet placement since you don’t have to worry about gravity and distance from the septic tank.
  • Less odor since the system prevents direct airflow from the black tank during the flushing process.
  • More efficient sewage disposal since the slurry can easily flow uphill and never backwards.
  • The system prevents clogging by liquefying the waste before discharging it into the black tank.


Macerators can pump uphill due to their design which liquefies the waste. After liquefying the effluent, the maceration device forces the slurry through thin pipes to create more pressure that aids in pumping uphill. Therefore, you can rest assured that using a macerator pump will not limit your toilet placement options, even when dealing with uphill sewage disposal.