In this section we will answer the following questions:
- What is turbidity?
- How is turbid water treated?
Turbidity is the cloudy appearance of water caused by small
particles suspended in the water. Water with little
or no turbidity will be clear. A maximum level of 0.5
NTU is allowable in groundwater.
Excess turbidity levels can occur in groundwater found in limestone
and unconsolidated rock formations. In addition, many
springs experience fluctuating levels of turbidity and extensive
monitoring of the water is required. All springs must
with a constant monitoring turbidimeter to shut off spring
pump operation if turbidity levels are excessive.
Filtration alone will not remove the turbidity and bacteria
in groundwater. In addition, a coagulation step is necessary
to concentrate the fine particles into floc, which can be
removed by filters.
Coagulation involves the addition of chemicals called coagulant
aids. Alum or polymers are often used for coagulation.
Then the water is allowed to settle for one to two hours,
which gives the coagulant aids time to concentrate the water's
suspended particles into floc. The settling period also
gives the chlorine contact time. The final step is filtration
to remove the floc. Rapid sand filters provide the best
A treatability study is suggested for any groundwater reading
treatment for turbidity removal. This study will ensure
the facilities will perform properly once constructed.
The Health Department will not approve this type of source
and treatment as a single water source because of the unpredictability
of groundwater quality.