Fact Sheet: Turbidity


Brief Overview:
Contaminant: Turbidity
Source: Erosion, soil runoff and discharges
Effect: Interferes with disinfection, filtration
Followup: For dormant wells or plumbing, run off and retest
Treatment: Filtration, or flushing

Any suspended particles in water which reflect light cause turbidity. In public systems this may be due to erosion runoff or other debris in the source water. In private wells turbidity is often caused by iron. Iron removal systems can be used to control turbidity in such cases.

There is no direct health effect for turbidity itself, however it interferes with disinfection processes which can affect the water quality. The presence of turbidity in public water systems can indicate a breakdown of the water treatment process which can indicate the water is of questionable quality.

When turbidity is found in public water it may be due to problems with the water treatment process, broken pipes, hydrant flushing or corrosion. Frequent testing for coliform is warranted.

Turbidity in well water is often associated with excessive iron. Descriptions of iron range from rusty colored water to mud in the water. When iron is ina particulate form it will show up as turbidity. Well water that is used infrequently (vacant properties especially) often has excessive levels of iron and turbidity. Run the water for one hour per day for about one week then retest. If the Turbidity persists filtration should be considered.

First retest and verify that the turbidity is not a temporary problem.
Turbidity can be removed by means of filtration. For mild problems a cartridge filter with a disposable filter element can be used. Cartridge filters are available from most plumbing houses and home supply centers. Filter elements are often rated by the average pore size. The unit is the micron or 1 millionth of a meter. Fifty micron filters remove only coarse turbidity sand grit etc. Twenty micron filters remove finer sediments and five micron filters remove most forms of turbidity.

Remember the finer a filter is the sooner it will coat with debris and need to be replaced. Most filter housings take standard filter sizes that different types of filters and different pore sizes can be tried.

Large amounts of turbidity or very fine particles may require filters that backwash automatically. The backwash reverses the flow of water through the filter media and flushes the accumulated turbidity down the drain. In certain instances pretreatment of the water with chemicals that cause coagulation is necessary.