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The plumbing solution when gravity is not your friend

The plumbing solution when gravity is not your friend


When you need a plumbing solution, but gravitational plumbing is unachievable as the plumbing fixtures are being installed below the main sewerage and stormwater drains, a well-located pump can be the perfect answer.

Architecture can be the most arresting and glamorous industry. We’ve all seen the impressive projects, the stunning images of amazing buildings that beautify our world and thrill the people who inhabit them. But these buildings are nothing without the fundamental infrastructure behind the scenes, the vital services and engineering components that mean the projects are functional and fit for purpose.

And nothing is more fundamental than the plumbing – the pipes and systems that serve to deliver water and remove waste water in a seamless and efficient manner.

In some projects this is a straightforward operation, particularly when building from scratch. But every architect will be familiar with the exceptions – those challenging projects that are either retrofits or situated in environments that require a different approach altogether – particularly locations where gravitational plumbing is not an option.

Often these two potential hurdles can be present at the same time, as what is required is an adaptive reuse of an existing underground space. How do you accommodate basins, dishwashers, washing machines, toilets, showers, baths and sinks in a space where the natural laws of physics do not apply?

Case study

The project

Carla and John Giannakopoulos have an open plan home in South Coogee New South Wales. In 2015 they made the decision to retrofit a space underneath the house to give an additional living area, which could act as a granny flat for both guests and family members needing privacy. The space needed to be self-sufficient and include washing and toilet facilities, but also a kitchenette with cooking and cleaning facilities – requiring the installation of a dishwasher and a washing machine.

The challenge

The designated space was behind the garage and its underground location meant it was also beneath the sewerage and stormwater main drains. Gravitational plumbing was not an option.

The process

When gravitational plumbing is inapplicable, alternative solutions will be sought by the project’s builder or a plumber. The architect may also be the one to do this. In the South Coogee project, the plumber recommended to the clients that the only way to solve the issue would be by the installation of a pump.

Site visit

An inspection of the site and face to face meeting with the client resulted in a complete list of the appliances and fittings required, while also providing detailed information as to the layout and available space.

Following this it was recommended that a Sanicubic 2 Pro be installed as the client needed a walk-in shower. With such a specification the pump needs to be lower than the fixtures – which means installing it below the ground or floor level. This is because when the pump is positioned lower than the fixtures in a pit, then the rest of the plumbing can be arranged conventionally and run under the slab. The under slab drainage gravitates to the pump positioned in the pit.

plumbing solutions
Sanicubic 2 Pro


The underside of the project space had already been excavated for the original garage, so minimal disruption was required. Internal drainage was set up in the ground before the concrete slab was poured and construction completed above. Taking approximately a day, the pump was discreetly installed beneath a closet. To mitigate any operational noise issues the pump was placed in a sealed pit with some acoustic insulation, beneath the floor of the walk-in wardrobe.


With a project like South Coogee it is impossible to do a cost comparison between the pump installation and gravitational plumbing, as the latter would have been impossible to implement. But in alternative situations where, for example, it was necessary to cut through concrete to get to existing drains that could be up to 20 or 30 metres away, the cost of this would outweigh the cost of a pump.

Ongoing maintenance

Once installed, it was recommended that a visual check of the alarm and control panel functions be carried out annually, but no other regular maintenance would be required.

The Sanicubic 2 Pro has a remote alarm function ability so the alarm panel can be positioned up to 80 metres away and is connected wirelessly


The client, Carla Giannakopoulos, was extremely pleased with the pump installation, saying, “It provides us and our visitors with privacy and it has given us another usable space. It has also added to the value of our home. Plumbing was basically impossible without it and we couldn’t have had the bathroom or kitchenette without the pump.”

This Saniflo AR Adviser article first appeared in AR163.

An AR adviser is an organisation with which the magazine has entered a partnership to provide expert insight from their respective industries.


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