CWC Multimedia Sand Filters

CWC is Africa’s leading supplier of multimedia sand filter technology. Our filters have been used in every application from drinking water to minewater reclamation and our client list includes South Africa’s largest manufacturers. In recent years we have developed a range of pre-engineered multimedia sand filter units to serve the small business, residential and light industrial markets.

What is a multimedia sand filter?

A multimedia sand filter is similar in operation to a conventional sand filter, but instead of using a single layer of filter sand, CWC multimedia filters use multiple layers of filter media.

The Deep Bed Multimedia principle offers a higher degree of filtration, longer filtration cycles and lower backwash water consumption than obtained from conventional sand filters or dual media filters.

The differing media layer depths and particle sizes also allow for far higher solids holding capacity without turbidity leakage.

The solids retention abilities of multimedia sand filters allow them to be operated at high filtration velocities, which result in reduced installation space and capital costs.

How they work

CWC multimedia filters contain multiple layers of filter media, each of different density, granule size and material. Each mineral layer promotes continuous filtration across its surface depth.

Water is fed into the filter vessel’s freeboard area, and forced through the filter media layers, exiting the filter outlet through specially designed nozzles, preventing carry-over of filter media. Suspended solids, turbidity and other particulate matter are trapped in the filter bed, producing clean, clear water.

Once the filter bed becomes blocked with dirt, a pressure drop across the system indicates that the filter should be backwashed. On automatic systems, backwashing is controlled by a timer or differential pressure switch. On manual systems, operator intervention is required to put the filter into backwash, much like a swimming pool sand filter.

During the backwashing cycle, water is forced through the filter in an upward direction, stirring up the filter bed and floating off the suspended particles. Because of the comparative weight of the filter media, only the dirt will be lost during backwash.

Once backwashing is complete, the direction of flow corrects and the filter bed is rinsed, removing any remaining dirt and helping the filter media resume its correct position inside the filter vessel.

CWC Multimedia Filters – Standard Features

  • Manual or automatic operation options.
  • Durable GRP or mild steel tank construction for corrosion resistance and high pressure operation.
  • UV resistant materials suitable for outdoor operation.
  • Simple inline configuration for ease of installation and maintenance.
  • Range of filter systems to suit household, commercial and industrial applications.


  • Automatic backwash controls.
  • Duplex kit to eliminate raw water bypass and system downtime.
  • Pressure differential backwash on automatic models.

Application and benefits

  • Food & Beverage Production-Improved taste and appearance.
  • Drinking Water-Reduces turbidity and suspended solids.
  • Boilers-Turbidity reduction, minimum sludge blowdown.
  • Industrial Process-Reduced particulate matter and turbidity.
  • Pretreatment-Ideal for Reverse Osmosis, Deioniser and softener pretreatment.
  • Car Wash-Turbidity reduction.

Design Considerations

In order to accurately size a multimedia sand filter for your residential, commercial or industrial application, we will need to know the following:

  • The amount of water you expect to use per 24-hour period.
  • Your peak water demand.
  • Operating hours per day.
  • Your water pressure.
  • The suspended solids content and turbidity of your water.
  • What you plan to use the filtered water for.

Your local approved CWC distributor can help you calculate your filtered water needs, and can arrange for a professional water analysis to be taken. For more information about multimedia sand filters and how the CWC filtration process can help you in your home or business, contact CWC today.

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