Water Clarification and Media Filtration: How to Remove Turbidity from Water


What is turbidity of water and how does it form?

Turbidity is a measure of the clarity of the water typically evaluated by means of nephelometric turbidity unit (NTU) which is based on light scattering methods. 

Water supplies are turbid as a consequence of suspended matter varying in concentration, from a trace in deep wells to thousands of mg/L in some rivers. Suspended solids include materials such as fine sand, clay, decomposed vegetation, bacteria, algae, and other microbiological organisms. Particles may be transported into the water streams through environment erosion, be suspended due to turbulence and mixing of decaying biological matter or precipitates from atmospheric pollution carried over by the rain. 

Turbid water contains suspended matter with varying particulate sizes. Settleable solids are particles large enough to settle while colloidal solids are particles that do not settle easily due to electrostatic forces. A rule of thumb is that settleable solids are greater than about 1 μm, while colloidal solids are less than 1 μm.

Why is it important to remove the turbidity of water and what are the limits?

In general, alongside colour, turbidity is the first impurity that is immediately perceived by the consumer as a quality parameter.

Apart from the merely aesthetic reasons, turbidity removal is essential to:

  • Ensure water is properly disinfected
  • Eliminate potentially toxic suspended solids (i.e. heavy metals)
  • Prevent the formation of scale and deposits in the mains distribution network

Regulation varies between countries and regions but a general rule of thumb is a turbidity limit between 0.5 and 1 NTU. The maximum limit of 1 NTU represents the approximate maximum turbidity threshold above which disinfection is not effective.

In many industrial plants turbidity can cause fouling of heat transfer surfaces and reduce efficiency of other systems.  

How can we help removing turbidity of water?

Depending on parameters such as your water composition, turbidity levels and origin, available footprint and project requirements we can help you with a  conventional media filtration plant or an ultrafiltration plant based on membranes.

Don’t hesitate to contact one of our engineers now who will help you with the best filtration treatment solution

Turbidity reduction with anthracite, sand and garnet media filters

Turbidity along with Iron and Manganese are the most common quality issues found in water supplies. The recommended limit of 1 NTU for turbidity is the approximate value above which disinfection is not effective.

Conventional media filtration with anthracite, sand and garnet is the most common filtration system for turbidity reduction. Typically used with any surface or bore water, this filtration method responds well to changes in the source water quality.

When turbidity > 10 NTU (up to 100 NTU),  flocculation and sedimentation or a two-stage filtration is recommended.

Contact us for a custom made design.

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*(1) All data for information only and subject to change based on actual water analysis and final design parameters


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