Bypass oil separators

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Protect your property, location and the environment by choosing Rewatec bypass separators, designed specifically for small spillage occurrences or where the risk of a spillage is low.

Rewatec bypass separator

What are bypass separators?

Rewatec bypass oil separators (formerly Conder bypass separators) are for use with surface water drainage systems and are designed to prevent hydrocarbons such as diesel, petrol and engine oil from mixing with surface water and entering drainage systems.

Bypass separators, which are also known as petrol interceptors, are used to fully treat all flows generated by rainfall rates of up to 6.5 mm/hr. They are used when it is considered an acceptable risk not to provide full treatment for high flows, such as low risk flood applications or where the risk of a significant spill is small.

Example applications

  • car parks
  • roadways, motorways and major trunk roads
  • light industrial and goods yards
Rewatec bypass separator


How does a bypass separators work?

Bypass separators are manufactured to treat all flow rates up to the designed nominal size. Any flow in excess of the nominal size (i.e. during heavy rainfall) is allowed to bypass the separation chamber, thereby keeping the separated and trapped oil or fuel safe.

Pollution prevention is a critical part of sustainable drainage systems and statutory regulations are in force to control the discharge of hydrocarbons such as oil or fuel.

Rewatec bypass separator operation


Step 1

During the early part of a rain storm, all the contaminated water flow passes through the sediment collection chamber and enters the separation chamber.

Step 2

All the oil then proceeds to the separation chamber where it is separated (through a coalescing filter) to the Class 1 standard of 5 mg/L and safely trapped. 

Step 3

As the rainstorm builds up to its maximum and the level of oil contamination reduces significantly, the nominal size flow continues to pass through the separation chamber and any excess flow of virtually clean water is allowed to bypass directly to the outlet.

If there is a regular risk of contamination from oil or a foreseeable risk of significant spillages, visit our full retention separator page for a solution that meets your needs.

Bypass separator maintenance

A full suite of services is available through Premier Tech’s extensive network of trusted service partners.

We stand by our products

For over 50 years, we have proudly developed sustainable and long-lasting products that make a real difference for our customers, our professional partners, and, above all, our planet.

Our experience in the industry allows us to give you a complete 25 year warranty for Rewatec bypass separators.

Rewatec 25 years warranty

Training programmes

​​​​​​At Premier Tech we provide a full range of training programmes to fully meet the requirements of our professional partners. If you require product functionality guidance or a more detailed training course for installations, we can provide a solution to meet your needs.

Contact us for more information

Technical information

Our Rewatec bypass separators are designed and tested to BS EN858 parts one and two, and can be installed for drainage areas ranging from 1,667m2 to 277,778m2

Rewatec bypass separator specification table


Here at Premier Tech, we understand that some sites require different pipework sizes to fit with the specific needs of the overall drainage system. If you have a requirement for larger or smaller pipework, contact us for a bespoke solution that meets your requirements.

Available products

We offer a complete range of Rewatec bypass separators to meet your needs. Wherever your site, whatever the regulations.



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