1. Potable Water vs Atypical
Pneumonia Risk Management &
Bionebulisation
CWWA, Ottawa
27th of November 2013

2. Transferable Approaches
TOC & Phosphorus :
• High levels increase tendency to form Biofilm.
• Concentration in CTs will be 3 to 6 times
higher

3. Transferable Approaches
Stale or slow moving water:
• Risk №1 demonstrated to cause outbreaks
Disinfectants:
• negative synergies, half life, Minimal Effective
Concentration, Corrosion, Contact time,
Temperature & pH effects.

4. Transferable Approaches
• Cyst control vs Amoeba & Protozoa
• Outbreak much more likely if water source is
from surface water
• Giardia & Crypto reduction may reduce risk
• Potable technologies difficult to transfer to CTs
• Zero risk does not exist.
• Risk = Probability x Consequences

5. Transferable Approaches
• Reservoir hydraulics
• Last in, last out reservoirs
• Cross connections
• Back-flow preventers
• IRBs : SRBs & Ferrogineous

6. Transferable Approaches
• Risk management: Critical control points,
Gradated risk management, Audits, Check lists,
Maintenance plan, Documentation & Tests
history, Training.
• Multiple barriers approach
• Use of indicators : fast drop in HOCl, Aerobes
levels, Turbidity
• Algae management-reduction
• Chemical pumps, controllers, sensors, on-site
chemical tests

7. Transferable Approaches
• ≠ Materials = Different tendencies for biofilm.
• Biofilm media: PVC high surface area
• CTs use exactly the same in cooling towers!
Coated to reduce surface tension? No.
Impregnated with silver ions-zeolite? No
• No kidding, no joke.

8. Counterintuitive & Different
• Fecal microorganisms vs water-borne
• Oral vs Inhalation
• Planktonic Vs Sessile
• Indicators in potable water allow validation.
NOT in CTs. There is no definitive validation in
CTs with a test.
• Finished water quality control vs Process QC

9. Counterintuitive & Different
• In CTs same bug (DNA) can be mostly
innocuous or highly pathogenic!
• Potable water can contain 3 logs of Legionella
that are non-cultivable but viable & infectious.
• You do it right nobody gets sick. In CTs we are
never sure.
• You can get away with important deposits &
biofilm. Not in CTs.

10. Counterintuitive & Different
Cleaning:
• Flushing does not work
• High levels of disinfectant do not work

11. Québec 2012: lessons
• Do not disinfect without having clean surfaces.
Remove the deposits 1st.
• Install high efficiency drift eliminators at the
onset : very low implementation
• Validate biocide concentration, contact time &
circulation at time of injection: >75% wrong.
• Involve external pros & a chemist (please)!

12. Québec 2012: lessons
• Have a plan of action. If this then that, etc.
• What, Where, How, When, Whom.
• Priorities.
• Work upstream of Legionella pneumophila.
• Do not ASSume.

13. Québec Law : the Excellent
• Mandatory documentation of actions & test
results.
• Schematics of the CT system.

14. Québec Law : the Excellent
• Maintenance plan signed by a professional
with an ethic’s code to be revised after:
1. Over limit Legionella result
2. Change to the equipment or systems
3. Changes vs the Maintenance plan

15. Québec Law : the Excellent
• Maintenance plan covers:
1. CT layout & start-up
2. CT operational stops & starts.
3. Decontamination
4. Normal operation

16. Québec Law : the Excellent

17. Québec Law : the Excellent

18. Québec Law – Interpretation - Who

19. Québec Law : the Good
• Law: any law is great.
• List of CTs, owners, localisation, tons.
• 40 inspectors actually visiting every CT!!!
– Systematic validation of back-flows, existence of
required signed documentation. Issuance of
‘tickets’ with 7 days to comply! Pictures.
• Technical guide & training sessions.

20. Québec Guide : the Good
• Iron as a virulence & amplification factor.
• Relationship between biofilm, amoeba & Lp.
• Association between deposits & Lp.
• Indicators & Lp analysis w/ action levels.
• Personalised planning.
• Hydraulic management.

21. Québec Law : the Missing
• ASHRAE 188, 62.1
• Penalties & Responsabilisation.
• Content of the plans & documentation.
• Not specific as to the actors: Eng, Chemist,
Water treat, Mechanics, Control cie., Chiller &
CT maintenance cies.
• Reducing agents as microbiostat –cide
• Risk analysis framework.

22. Québec Guide : the Bad
• False information:
1. Non oxidizing biocides can be measured with test
kits on site or off-site (GC).

23. Consumption Implications

24. Reduced consumption
• When risk is perceived as hard to control then
managers replace CTs with Air-cooled units.
• ~ 2x more energy consumption
• HVAC: 40-60% of the bld energy consumption.
• Buildings = 39% of total energy consumption.
• Island heat effect amplified. In Paris over 3°C.
• Ex. L’Oréal

25. Increased Consumption
• Fastest way to reduce risk is to reduce cycles
of concentration
• Also improves energy efficiency
• Increases water consumption. Usually 2nd
biggest after toilets & urinals.
• Increases proportion of water returned to
drain.
• Reduces water gas thus reducing Island heat.

26. District Cooling – Water2Water
• Ex. Toronto, Morocco.
• No potable water or net water use.
• Energy & GHG savings.
• No island heat effect. Less smog.
• Increased floor space & competitiveness.
• Less city hollowing.
• NO LEGIONELLA RISK

27. Quantitative Microbiology
Case: 1000 tons CT, 35% in operation, Lp within
guidelines at 3 logs
Drift eliminators at 0.5% vs 0.0005% efficiency
20 000 vs 20 cfu Lp/minute
Material cost of about 300$/CT
CTI’s 1st recommendation is for validation of
drift control. Never followed.

28. Questions, Comments ?