Typical Contaminants And Problems
Agriculture and Natural Resources WATER QUALITY: Managing Drinking Water Quality
A & M
Typical Contaminants And
Turbidity (Cloudy Water)
ater drinkers find turbidity objectionable priW
marily because the physical appearance of dirty
water is less appealing than clear sparkling water.
Turbidity caused by inorganic minerals is undesirable
because its abrasiveness can erode a plumbing system’s pipes and fittings and score its valve seats and
washers. Turbidity caused by suspended organic matter is objectionable because it can stain sinks and fixtures and discolor laundered fabrics. Suspended matter can also carry pathogens.
The main problem turbidity causes is interference
with disinfection processes. Bacteria, which are usually present in turbid water, can be protected from
chlorine and other disinfectant techniques.
Causes Of Turbidity
Cloudy or muddy water is caused by the presence
of fine suspended particles of clay, silt, algae, or
organic matter. Solid particles suspended in water
absorb or reflect light and cause the water to appear
cloudy. These particles are picked up as water moves
over or under the ground. Since the surface of the
earth acts as an excellent filter, the water from deep
wells is usually clear without significant amounts of
turbidity. Turbidity is more common in the water
from surface supplies.
In fractured bedrock aquifers, cloudy or gritty
water may occur as a result of blasting, construction
activities, or surface water intrusion.
If cloudy water routinely occurs after rainfall and
snow melt, either your well has a leaky casing or rock
fractures are allowing rapid movement of surface
water into the well.
Treatment Of Turbidity
When To Treat: Turbidity in excess of 5 NTU is
usually objectionable for esthetic reasons. If the
amount exceeds 10 NTU, the water may contain bacterial contaminants and may not be safe to drink.
How To Treat: Activated carbon filters or mechanical filters remove turbidity. Two different types of
mechanical filters may be used individually or in
combination. One is the sand filter and the other is the
cartridge filter.
A sand filter is best for removing heavy loads of
suspended particles while a cartridge filter may be
used as secondary filtration at the point of use to
remove very fine particles not removed by the sand
filter. If the turbidity concentration is relatively low, a
cartridge filter may be all that is needed.
Public water systems using surface sources provide full treatment, including filtration. Many systems
with turbid groundwater also provide filtration.
Reverse osmosis and distillation also successfully
treat turbidity.
Turbidity At A Glance
Symptoms: Cloudy or gritty water; water pipes, filters, and water heater plugged.
Causes Of The Problem: Fine sand, silt, and clay
passing through well screen; suspended particles of
organic matter; precipitates forming in water from
temperature or pressure changes.
Suggested Treatments: Activated carbon filter,
mechanical filter (sand or cartridge), reverse osmosis,
or distillation.
Prevention: Make sure well is sealed from direct surface contamination. Repair or replace well screen.
Soften the water to prevent precipitation of scale.
Hermanson, Ronald E. 1991. Turbidity, Color,
Odor, And Taste In Domestic Water. EB0994. Washington Cooperative Extension Service. Washington
State University. Pullman, WA.
Haman, Dorota Z., and Del B. Bottcher. 1986.
Home Water Quality And Safety. Circular 703. Flori-
Water Quality 2.3.4
Visit our Web site at: www.aces.edu
da Cooperative Extension Service. University of
Florida. Gainesville, FL.
Shaw, Byron H., and James O. Peterson. 1990.
Improving Your Drinking Water Quality. G3378.
Wisconsin Cooperative Extension Service. University
of Wisconsin. Madison, WI.
Tyson, Anthony, and Kerry Harrison. 1990. Water
Quality For Private Water Systems. Georgia Cooperative Extension Service. The University of Georgia.
Athens, GA.
This publication, supported in part by a grant from the Alabama Department of
Environmental Management and the Tennessee Valley Authority, was prepared
by James E. Hairston, Extension Water Quality Scientist, assisted by Leigh Stribling, Technical Writer.
For more information, call your county Extension office. Look in your telephone directory under your county’s name to find the number.
Issued in furtherance of Cooperative Extension work in agriculture and home economics, Acts of May
8 and June 30, 1914, and other related acts, in cooperation with the U.S. Department of Agriculture.
The Alabama Cooperative Extension System (Alabama A&M University and Auburn University) offers
educational programs, materials, and equal opportunity employment to all people without regard to
race, color, national origin, religion, sex, age, veteran status, or disability.
UPS, New June 1995, Water Quality 2.3.4
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