Applications of Emerging Technologies in the Drinking Water Sector - Waterborne Pathogens: Detection Methods and Applications - page 355

11.6.1. Detection
Water needs to be monitored before human consumption to ensure there
is no presence of pathogens including bacteria, viruses and protozoa that
could potentially cause disease and illness if digested. The detection of
pathogens is important and can be done with a variety of methods. There
are a variety of current systems or methods available for detection in the
water supply sector within the UK. 47 The sector mainly relies upon the
use of fecal indicator monitoring as a safety check of the finished drinking
water. As noted in earlier chapters, this method has been well-used for many
years and has contributed to advancing drinking water quality. However,
there is sometimes a lack of correlation between pathogen presence and
fecal indicator markers.
Cryptosporidium is the only pathogen for which direct detection is per-
formed. The current system used for the detection of Cryptosporidium in the
UK involves the use of a filtration system. Currently, those systems recom-
mended under UK guidelines for the drinking water section in the UK are
either the IDEXX or Pall filtration systems. However, the majority of the
market share is claimed by IDEXX. While the method is relatively expensive
and time-consuming, the long-term market dominance of IDEXX, along
with the conservative nature of the water industry, makes it challenging for
new companies to enter the market. Other difficulties include the relatively
small market size and the potentially high cost of entry for a new supplier.
Established methods for detecting pathogens in water include the fol-
lowing:
1. PCR —A method developed in the 1980s. It involves using nucleic acid
amplification technology and has widespread use in bacterial detection.
It entails isolating, amplifying and quantifying a short DNA sequence
in the targeted bacteria's genetic material. 47 The unique DNA of the
pathogen is detected so scientists can construct oligos to detect the
pathogens. These methods are advantageous in that they are very sensi-
tive; however, they are not always capable of reliably detecting or quan-
tifying viable organisms because they may also detect the nucleic acid of
noninfectious microbes. 48
2. Culture and colony counting methods —The oldest bacterial detection tech-
nique and still the widespread, standard method. It is considered to be
the most accurate and reliable method but it is time-consuming due to
the amount of time required to wait for results (often 2-3 days for initial
results, then a further 7 days for confirmation). The method involves cul-
turing and plating, after which different selection methods are applied to