Turbidity, impurities

Water turbidity is usually caused by small particles which can be of organic or inorganic origin. Cloudy soiled water is less drinkable, often even just from visual aspect. The turbidity usually ocurrs all od sudden, for example when it gets to the system from outside and hydraulic terms are changed. During such penetration the settled substances are released from the walls of pipes.

Turbidity arises by pipe corrosion, when biofilms and incrusts fall apart or due to chemical processes from water treatment plants. Outer environment can be contaminated, too.

Limits of turbidity in Czech Republic are set on 5 ZF (formazine units)

Risk factors or the turbidity arising are: increase of usage, blowdown of the network, change to the water flow direction or malfunction on a water treatment plant. During all these cases unwanted impurities get into the water.

Characteristics: water turbidity, dirty water, soiled water, sediments, brown water, impurities in water

Possible causes of turbidity

Corrosion in pipes >>

Water pipe networks can be a problem when metal pipes are used or there is an incoming water which could contain such particles. The biggest risk are pipes which haven’t been serviced for years or have some kind of surface treatment (zinc etc.). Corrosion also easily happens when water is too soft or has too low pH.

Unsuitable hydraulic conditions

If the water runs through pipes too slowly, an unpaved sediment layer sticks to the walls over time. These impurities then get to the water at once when water gets stirred.

The slower the water, the thicker the layer of sediment can be.

Optimal speed of water flow in pipes is above 0,25  m/s.

Poor quality of water

Turbidity can be also caused by too much manganese or iron. If the water treatment plant has malfunction, water can have unsuitable properties from the start. Also some form of pollution can be released into water during the regeneration cycle of the cartridge. Water treatment plant can also use iron salts as coagulants and they stay in water then.

Poor service

For optimal function in the network it is necessary to perform a regular service when sediments are removed from the pipe surfaces. It is advised to clean the storage tanks carefully, as well as reservoirs and pumping stations. Biofilms and sediments are often present there which can be stirred during the operation.

Pollution of the water from outside

Water pollution from outside often happens during various repairs or pipe assembly when polluted surface water leaks through.