Cleanawater on 20 October 2016

Water treatment information for Australian businesses

What is an oil water separator?

An oil water separator is a piece of equipment used to treat wastewater, making it safe to discharge into an approved discharge point, such as a sewer. It removes oils, grease and hydrocarbons, leaving only the non-hazardous water. The wastewater can then disposed of safely in drainage.

There are a few different kinds of oil water separators. Each has different capabilities, and they are used for different commercial and industrial applications. They are used to treat a variety of contaminants found in water, including free-floating oil, emulsified oil, dissolved oil, and suspended solids.

At Cleanawater, we have decades of experience and expertise in treating wastewater. Get expert advice on wastewater compliance and oil water separators for your business

When do you need an oil water separator?

For many Australian businesses, using an oil water separator will be an essential part of achieving compliance with local water authority regulations. If your business is not compliant, you may have to pay large fines or your operation may be suspended until you are compliant.

You will need an oil water separator if you:

  • Produce wastewater as part of normal operation
  • Discharge that wastewater into public drains
  • Must 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

Different types of wastewater will often require different types of oil water separators to effectively treat the water. The four common types of oil water separators are:

  1. Coalescing plate separators
  2. Vertical gravity separators
  3. Hydrocyclone separators
  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 plate separators 

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 the surface area. Upon impingement on media packs, droplets rise to the surface and are skimmed off into a waste oil container.

They're easy to install and maintain, and they will ensure you meet or exceed water authority regulations. 

2. Vertical gravity separators

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.

Their small footprint and optional hot water handling unit make them perfect for commercial kitchens, and industrial sites. They're also easy to maintain, thanks to the durable stainless steel construction.

3. Hydrocyclone separators

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 pits

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 need oil water separators

Oil water separators are essential in a wide range of businesses and industries. Any business which produces wastewater may need an oil water separator to achieve compliance, 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. There are many other businesses and industries which also need oil water separators and other wastewater treatment equipment. If you are unsure of the wastewater treatment requirements for your business, talk to our expert technicians for advice. 

Why wastewater treatment 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.

It is the business owner's responsibility to ensure they are compliant with wastewater treatment regulations. If you're not sure if your business is compliant or not, you need to seek expert advice as soon as possible.

Talk to Cleanawater for expert advice on 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's requirements to the final installation of the appropriate system, we do it all for you.

Get in touch with our team to learn more about the right oil water separator for your business.