Cleanawater on 20 October 2016

Water treatment information for Australian businesses

What is an oil water separator?

An oil water separator is a device used to treat wastewater to a standard where it is safe for discharge into an approved discharge point, commonly a sewer. It removes oils, grease and hydrocarbons, leaving only the non-hazardous water, which can be disposed of safely in drainage.

Australian businesses will require an oil water separator if they are:

a) Producing wastewater as part of normal operation
b) Discharging that wastewater into public drains
c) Wanting to achieve water authority compliance

The exact type of oil water separator required by any given business will depend on the type of wastewater being produced and the area's local water authority requirements.

Different types of oil water separators

Oil water separators are typically divided into the following four categories:

  1. Coalescing
  2. Vertical gravity
  3. Hydrocyclone
  4. Petrol and oil interceptor pits
3 types of oil water separators

From left to right: Coalescing, Hydrocyclone, Vertical Gravity

The function of each device is the same, to treat wastewater to a level where it is safe for discharge. However, the way that each system achieves this is different.

How each system works

1. Coalescing
One of the most commonly used models, coalescing oil water separators remove oils, grease and hydrocarbons from wastewater while adhering to predefined discharge standards.

Media packs are positioned in two stages to force free oil droplets to impinge on surface area. Upon impingement on media packs, droplets rise to the surface and are skimmed off into a waste oil container.

2. Vertical gravity
Vertical gravity separators operate by controlling both fluid velocity and pressure. These forces are utilised to separate impurities from water, thereby allowing the contaminants to drain off into waste areas.

3. Hydrocyclone
Hydrocyclone oil separators work by sending wastewater through a 'cyclone chamber', which applies extreme centrifugal forces. This intense force causes the water and oil droplets to separate.

4. Petrol and oil Interceptor
These systems typically feature two to three compartment gravity flow systems which work on the premise that hydrocarbons, petrol, and diesel float above water. Therefore, contaminates can be separated and skimmed from wastewater.

Businesses and industries which use them

Oil water separators are used across a range of business types and industries. Including:

Businesses Industries

Mechanics and car workshops


Service stations


Car dealerships

Food processing

Commercial car washes

Quarantine (AQIS)

These are the sectors where oil water separators are most commonly used. However, they can still be used in other sectors, when and where treatment of wastewater is required.

Why treatment of wastewater is so important

Australia's waterways and local environments are precious. They're vital for the preservation of Australian flora and fauna, and for ensuring our ease of access to clean and safe water.

The discharge of untreated wastewater into stormwater drains and local estuaries can cause significant harm to these environments and waterways. Water pollution can poison native species, cause long-term damage to delicate ecosystems, and make water unsafe for human interaction.

It's not surprising then that the discharge of wastewater from commercial operations is tightly regulated by organisations such as the Environmental Protect Agency (EPA) and local water authorities.

Businesses which do not effectively manage their wastewater with oil water separators and other water treatment devices can face heavy fines, closure of premises, and in some cases even prosecution.

Check out our range of oil water separators

At Cleanawater, we specialise in the design, manufacturing and installation of water treatment systems. And, we build our systems right here in Australia, for Australian conditions.

We can provide you with a complete oil water separator solution. From assessment of your business' requirements to final install of the appropriate system, we do it all for you.

To find out more visit our oil water separators page or call 1800 353 788