Rapid Gravity Filters

Offering a very robust and proven water purification solution with low operating and maintenance costs, commonly used as part of a multiple-stage treatment system.

About The Technology

Each of our filters are engineered to meet the specific performance requirements of individual water treatment plants. We have a wealth of experience in both providing new RGF solutions and upgrading existing RGF’s. Our new filters can be provided within concrete structures or as prefabricated systems.

Colloide’s Rapid Gravity filters are designed as a single or multi media solution to meet the application with an overall depth of between 500 -3000mm. Common media include silica sand, manganese dioxide, anthracite and activated carbon.

The water travels downwards through the filter bed, the solids are captured by the filter media and the clean water is discharged through the base of the filter. As a result of the filter capturing these solids, over time the filter will start to block at which point it will be taken off line for a backwash in order to ‘clean’ the filter before returning it to service – a process which  takes approximately 20 minutes to complete. We use a state of the art backwashing process to achieve this clean, PLC controlled with an operator interface panel or PC.

The filters are generally PLC controlled with an operator interface panel or PC used to all the operator to view the plant operation and change parameters.


Why our Rapid Gravity Filters?

We offer a variety of filter underdrain systems – from conventional lateral type to monolithlic floor to modern dual lateral type. In this way, we can provide our Clients with a range of options

Variations in filter media available to suit each application

Through Colloide’s technical knowledge and experience, we can provide alternative backwash regimes to suit each application, with a focus on extending run times and reducing backwash water.

Our RGF is based on a very proven and reliable process

We offer our RGF’s as packaged filters which can be built off site OR as concrete filters which have their shells constructed on site with Colloide then installing the equipment within these on site.


These RGF’s are used in many different applications within a potable water treatment;

  • Roughing filters.
  • Post clarification filtration.
  • Direct filtration.
  • Carbon filtration on the back end of works.

These filters provide an effective barrier to many drinking water contaminants, with excellent removal of turbidity, metals, microorganisms and colour.

When used for wastewater treatment, the solids removal reduces BOD/COD levels in the treated wastewater. These RGF’s may also be used for nitrate (NO3-N) removal and/or phosphate removal.

Related Projects

Here’s just some of the planet protecting projects we’ve worked on.

Get In Touch

If you’re interested in creating a brighter tomorrow, we want to work with you.

Alternatively, visit our office.
Derryloran Industrial Estate, Cookstown, BT80 9LU