Risk Assessment for Safe Drinking Water Supplies - Global Drinking Water Management and Conservation - page 121

Biological hazards include pathogens such as bacteria, viruses, protozoa, and
helminthes. Other nonpathogenic organisms are asellus and Cyclops. These may
originate from human or animal fecal material contaminating raw water that

nds

its way into the water supply delivery system.
There may also be radiological hazards as a result of contamination by man-
made sources of radiation. These could arise from: naturally occurring radioactive
species in drinking water sources; the contamination of water from the mining
industry; or from radionuclides from the medical or industrial use of radioactive
materials.
The risks are best prioritized by setting up a matrix of all relevant hazards. The
team may rely on their a priori knowledge to assign to the hazards or

may weight hazards according to seriousness. These numbers will end up taking the
form of subjective probabilities as objective probabilities will probably not be
available.
Then

“ numbers ”

ned as those steps that directly affect water
quality, and which collectively ensure that water consistently meets health-based
targets. They are activities and processes applied to prevent or minimize hazards.
All actions that can mitigate risks from some speci

“ control measures ” are de

c events would also be docu-
mented. In particular, appropriate action is to be taken at the point of contamination,
so that the effect of multiple barriers can be assessed together.
There are a number of ways to control pathogen entry into the water, for
example, by reducing their entry into the water supply; reducing their concentration
once in the supply; and reducing their proliferation. Another measure is source
protection; decreasing contamination of source water will result in the amount of
treatment and quantity of chemicals needed being reduced. This may further reduce
the production of disinfection byproducts and reduce operational costs. Prohibiting
polluting activities can enhance source protection. An important measure is pro-
moting awareness in the community of the impact of human activities on water
quality.
The next important step is which requires conducting a planned

series of observations or measurements of operational and/or critical limits to assess
whether the components of the water supply are operating properly. The monitoring
should be applied to each control measure. It also requires establishing a rela-
tionship between control measure performance (determined by measureable
parameters) and hazard control performance. For example, with or without a
SCADA (supervisory control and data acquisition) system, it is still necessary to
monitor chlorine residuals, pH, and turbidity, which will further indicate if more
hazards are present or not.
A proper Monitoring Plan would include: a list of parameters to be monitored;
sampling location and frequency; schedules for sampling; methods for quality
assurance and validation of the sampling results; the proper interpretation of
sampling results and any follow-up required; documentation and management of
records, including how monitoring results will be recorded and stored. There will
also be requirements for reporting and communication of results.

“ monitoring, ”