SCIENTIFIC SERVICES

– DEVELOPMENTSAngela Dignan

Team Manager

Inverness Laboratory

Scottish Water

Lab Developments - Inverness

Crypto Filta-Max xpress validations

Drinking Water Directive preparedness

Chemistry – new analyser, UoM validations

Flow Cytometry – improvements to method & new analyser

Study Supporting the Directive

• Recommends incorporating Somatic Coliphages as a new

parameter to verify sufficient elimination of enteric

bacteria before leaving treatment works

• Somatic Coliphages share many properties with human

enteric viruses – composition/morphology/structure

making them good models in which to assess behaviour

of enteric viruses

(WHO, 2017)

Most common morphological types

Drinking Water Directive Impact

(currently.. )

CurrentRegs rrDWD

Row Labels RSZ SR WTW RSZ SR WTW

Clostridium perfringens (Sulphite Reducing

Clostridia) 5514

Coliform Bacteria (Total coliforms) 14936 50048 26079 50048 26079

Colony Counts After 3 Days At 22øc 14936 50027 26079 50027 26079

Colony Counts After 48 Hours At 37øc 14936 50081 26079

Colour 5551

Conductivity 5551

E. coli (Faecal coliforms) 14936 50048 26079 4122 50048 26079

Enterococci (Faecal streptococci) 1617 4122

Hydrogen ion (pH) 5551

Odour 5551

Somatic Coliphages 4122Taste 5551

Turbidity 5039 7117 7117

Clostridium perfringens including spores 4122

Legionella

Grand Total 99,669 200,204 111,433 16,488 150,123 85,354

Somatic Coliphages – Need for Viral Indicator

• Bacterial pathogens are

responsible for a large number of

outbreaks

• Coliphage can be an indicator of

viruses in ambient water

• There is no such as an ideal

indicator, this is perhaps the

closest to ideal

• Good microbial indicator should

be

• Safe to work with

• Easy to analyse for

• Inexpensive

• Sufficiently reliable

Water Environment Federation, 2019

Method –

Double Layer

Assay

Sample mixed with MS

broth to which a culture

of host strain added (e-

coli)

This is poured onto an

MS agar plate

Sample incubated

No or visible plaques

can be counted

Reported as pfu/100ml

Jofre et al., 2016)

Why use Coliphages as a viral indicator?

Feacal Origin

Physically similar to enteric viruses

Similar persistence patterns to enteric viruses

Non-pathogenic

Easy to detect in the laboratory

What do studies tell us?

Espinosa et al (2009)

• Freshwater

• Strong association between F-specific and enterovirus

• No other association

Lodder et al. (2010)

• Surface Water

• Significant association between densities of coliphages (F-specific & Somatic) and enterovirus

• Found no coliphages present where enteroviruses were present

• Concluded useful for treatment efficiencies

Payment & Locas(2011)

• Groundwater

• Not predictive of virus presence or absence

• Partly due to low numbers present and their infrequent detection

Are they the best indicator?

(Wu et al., 2011)

Suitability for Drinking Water

• Will there be a detectable level in drinking water? They

only use e.coli as a host

• Do they replicate sufficiently enough?

• Would it be more suitable as a treatment efficiency

performance measure?

• Should F-specific also be included?

Summary

Pros

• It is the most suitable viral

indicator for lab analysis

• Derives from feacal matter

in human and animals

• There is a need to monitor

viruses in drinking water

• Good measure treatment

efficiency

• Build up our knowledge

bank of viruses in water

Cons

• Low numbers in drinking water may make detection difficult

• More research is needed in drinking water to prove that there is a health benefit to doing this

• Some studies have found F specific coliphages to have a larger association with enteric viruses

• Not as reliable as current FIB i.e. coliforms/e-coli

Conclusions

Somatic Coliphages are a better viral indicator than current FIB

There appearance in drinking water is dependent on suitable e.coli host to be

present and replicate

The answers will only become apparent for each water source after testing has

been carried out.

References

• Water Environment Federation “Coliphage Analyses for Wastewater and Recreational Waters:

Updates on Methods and Regulations, May 2019

• Environment Protection Agency “Review of Coliphages as Possible Indicators of feacal

contamination for ambient water quality”, 2015

• https://ec.europa.eu/environment/water/water-

drink/pdf/20171215_EC_project_report_final_corrected.pdf “Support to the revision of Annex 1

Council Directive 98/83/EC on the Quality of Water Intended for Human Consumption” World Health

Organisation, 2017

• Juan et al“Coliphages as Model organisms in the Characterization and Management of Water

Resources” 2016