Before You Start

1. Legionellosis Study CourseHot and Cold Water Systems Before You Start The following screens will outline the control of Legionella with specific regard to hot and cold water systems. Some of the screens advance automatically but most will need you to click your left hand mouse button or hit the space bar. This ensures that the presentations run at your own pace. time to hit or click

2. Introduction Legionella Needs Causal Chain Diagram of Typical System Incoming Water Supply Cold Water Systems Design and Construction Operation and Monitoring Scope of Course • Hot Water Systems • Design and Construction • Operation and Monitoring • Cleaning and Disinfection • Alternative Control Methods • Record Keeping • Written Schemes

3. Historically, hot and cold water systems have been associated with more reported cases of legionnaires disease than the more publicised outbreaks associated with cooling towers. There have been fewer outbreaks in recent years but poorly maintained and badly designed systems still present a significant risk. We need to consider all elements of a water system (incoming water , storage vessels and outlets) and assess the risks of proliferation of Legionella and possible dissemination. A typical hot and cold water system is illustrated in a few slides time but before looking at this slide let us consider again the ideal growth conditions for Legionella and the causal chain for infection to occur. There are a wide variety of system designs including recirculating gravity systems , non-recirculating gravity systems and pressurised systems. You should consider the risks as presented and how they apply to your own unique systems. Introduction

4. Legionella Needs • All organisms have their favoured temperatures and Legionella is no exception • 20 to 45 °C is ideal for growth and reproduction • below 20 °C the rate of cell reproduction is significantly inhibited • at 45 to 50 °C cell multiplication is reduced but cells are still viable • above 60 °C cells start to die and the numbers fallrapidly • Nutrients • Legionella requires very specific nutrients, such as Iron. For this reason corrosion free systems will help reduce possible contamination and bacterial ‘hideouts’ • Habitats • All microbes grow better if undisturbed and out of reach of biocides such as chlorine • Oxygen • Oxygen can enter water systems through a number of routes such as the make up ball valves to cold water storage tanks. Mains water is in itself sufficiently oxygenated to support microbial growth

5. Causal Chain Aerosol Production controlled by good design High Concentration of Bacteria treated by effective treatment / temperature Contamination controlled by good incoming water and treatment Susceptibility of Individuals Duration of Exposure managed by safe operation & maintenance procedures Droplet Size controlled by good design Heavy Smoking Virulence of Strain we do not want to rely on this! Male Over 45 years of age Immunosuppressence

6. COSHH Primary Objective “The primary objective should be to avoid conditions which permit legionella bacteria to proliferate and to avoid creating a spray or aerosol. It may be possible to prevent the risk of exposure by, for example, using dry cooling plant, adiabatic cooling systems or point-of-use heaters (with minimal or no storage). Where this is impractical, the risk may be controlled by minimising the release of droplets and by ensuring water conditions prevent the proliferation of legionella bacteria.” - ACoP L8 Just because there’s always been a cold water storage cistern does not mean that one is actually necessary. An evaluation of removing the tank should at least be carried out before remedial works are carried out. V

7. Typical System Think about where Legionella could multiply in your system and compare it with the diagram below Legionella could multiply anywhere in the system where temperatures are >20oC and <50oC and stagnation occurs Legionella may enter here but should remain dormant unless allowed to stagnate or warm up in the presence of nutrients Legionella could begin to multiply in the cold water distribution pipe work through thermal gain and low flow The pipe work between the outlet and the hot water circuit is prone to further growth of legionella when the outlet has not been used for a few days Dangerous aerosols can be produced via showers, spray taps or even conventional taps. Infrequently used outlets pose the greatest threat Washbasin Potable Water Bath Lower temperatures at the base of the calorifier and the sediment accumulated there, provides an ideal habitat for legionella which can then colonise the rest of the system Shower WC

8. Water systems can be contaminated with Legionella from small numbers of the bacteria entering via the mains water or a borehole supply The water supply companies can only maintain wholesome water quality up to the boundary of any property. The water quality within the boundary of a site is entirely the responsibility of that site. Since Legionella is found naturally in the environment it is not feasible to guarantee that Legionella will not enter your systems in some way Where borehole water, is used sites are now required under the water supply regulations 1999, to provide water quality to the same standard as the traditional water supply companies. Care should be taken to ensure that the quality of any borehole supply should not compromise the hygiene of the water systems on a site Further growth of Legionella will only occur in the presence of higher temperatures such as heat gain in plant rooms and with nutrients and stagnation. Interestingly, the water supply companies can supply water up to 25°C to your site boundary - we will see the significance of this in the next slides! Incoming Water Supply

9. Cold Water Systems [Design & Construction] Cold water storage systems should be designed to avoid the conditions favouring growth of Legionella and to allow easy cleaning and disinfection or inspection. Tanks should comply with the water supply (water fittings) regulations 1999 (old Byelaw 30) and should therefore have ; • Storage capacity of less than 24 hours • A tight fitting lid with inspection hatch • allowing inspection without damaging the • insulation • Insect screens fitted to the vent, overflow • and warning pipe preventing foreign objects • and debris entering the system. • The inlet opposite the outlet, ensuring a good • flow of water through the tank preventing • stagnation hotspots. Important note : A great way to eliminate the risks presented by cold water storage in open tanks and large volumes, is by moving to mains pressure systems, with Reduced Pressure Zone (RPZ) valves replacing tanks. • Insulation all over to prevent greater than • 2 °C heat gain • A good working drain fitted

10. Cold Water Systems [Design & Construction] V Avoid multiple linked storage tanks because of possible stagnation. Ball valves have not been designed or manufactured by NASA, so one ball valve will always tend to lead the other, leading to a low flow through the other tank. Where multiple tanks are required, align them in series to ensure a good flow.

11. Cold water should be below 20oC at all times The incoming cold water inlet temperature should be measured at least once in the winter and once in the summer. Cold water storage tanks should be visually inspected annually and should be cleaned and disinfected if necessary and any faults rectified. See slide on cleaning & disinfection later Record the total water consumption over a typical day and whenever the building use changes, this should be repeated. Check nearest and furthest cold water outlet temperatures are below 20oC within 2 mins. flow on a monthly basis. A representative number of cold water outlets should also be tested on a rotational basis once a year. Install high use outlets upstream of lower use outlets to maintain flow. Review cold water circuit plans annually and remove redundant outlets Cold Water Systems [Operation & Monitoring]

12. Hot water systems pose the greatest threat of legionellosis - consider ‘point of use’ water heaters as an alternative to stored hot water systems Calorifiers should be sized to meet normal daily requirements whilst maintaining flow temperatures of 60oC Multiple calorifiers should be connected in parallel All calorifiers should have an accessible drain valve at their lowest point Return temperatures should be >50oC and outlet temperatures should achieve 50oC within 1 minute Timer controlled shunt pumps should be considered if water temperatures cannot be maintained above 60oC throughout the calorifier at all times Hot water distribution pipes should be insulated and trace heating employed where necessary Hot Water Systems [Design & Construction]

13. Hot Water Systems [Design & Construction] Return vent from the calorifier should go to a tundish and NOT return to the cistern Cold water feeding hot water system must be insulated Duty/stand-by pumps should be rotated weekly Temperature gauges should be fitted to flow and return pipes Hot Water Systems T Calorifier or hot water system must store the water at 60 oC T If the services are a long way from the calorifier then return lines should be fitted A good working drain should be fitted

14. Hot Water Systems [Design & Construction] Hot water flow Shunt Pumps Required for calorifiers where thermal stratification occurs internally thereby allowing legionella to grow in the base. They take water at 60oC from the top of the calorifier to the base to kill any legionella bacteria that may be present due to the lower temperatures. They should be set to operate for 1 hour per day during a time of low demand. Hot water return

15. Calorifiers on standby use or out of service for >7 days should be thermally disinfected at 60oC for on hour AVOID TEMPERATURES BETWEEN 20oC AND 50oC Store hot water >60oC and distribute >50oC Where scalding is a risk, use thermostatic mixing valves Remove dead-legs and cut back redundant outlets Infrequently used outlets and particularly showers, should be flushed weekly for several minutes to prevent stagnation Calorifiers should be drained and inspectedannually. The system should then be cleaned and disinfected Flow and return temperatures should be loggedmonthly. Building Management Systems (B.M.S.) may be used to automate this task Check that the nearest and furthest hot water outlet temperatures are above 50oC within 1 min flow on amonthly basis and a representative number of other outletsonce a year Hot Water Systems [Operation & Monitoring]

16. Hot Water Systems [Reason for Maintaining Temperature] • Stratification, scale and sediment can lead to a primary legionella reservoir establishing itself in the base of the calorifier. • Should the temperature drop during a period of peak demand, legionella can escape into the main circuit where it can establish itself into the distribution legs as a secondary reservoir. • Thermal disinfection of the calorifier now becomes ineffective as legionella in the distribution legs and can seed the rest of the system 2 Washbasin 2 Bath 1 2 Shower WC

17. Distribution Systems [Design & Construction] Ensure pipe work in the ducts is fully insulated and clearly identified. Check valves to ensure good circulation and one is not acting as a dead leg. Check that hot and cold pipes do not touch. Ensure the hot pipe is above the cold pipe or that both are insulated individually to prevent thermal gain. Outlets and especially aerosol producing ones like showers, must be checked and maintained. Isolation valves

18. Distribution Systems [Design & Construction] Booster pumps if required should be placed so that they can easily be checked on a weekly basis to ensure they are operating correctly. Pipe diameter should be as small as possible to avoid low flow due to being oversized. Low use outlets should never be downstream of high usage outlets as this will cause stagnation. This can be remedied by simple re-engineering. (All infrequently used outlets should be flushed at least weekly). An alternative would be to put a verifiable double check valve after the T to the tank. Safety shower CWST

19. Schematics • Schematics are required for complex water systems such as larger hot and • cold water systems • The schematics should contain all relevant associated plant and • valves • They should identify all associated pipe work, including blind ends • and dead legs which should be highlighted • The plans for both the hot and cold water circuits should be • checked annually to ensure that they are up to date and updated if • necessary • For an example of a schematic and what symbols are used, go to • www.fineapply.com, click on the download section and then example • schematic.

20. Systems should be cleaned and chemically or thermally disinfected, if the system has been altered or contaminated by maintenance activities, or after an outbreak or when inspection suggests it is necessary CHEMICAL DISINFECTION - (Usually to BS6700:1997) Chlorinate tank to 20-50 mg/l free chlorine and flush through ALL of the system and then leave to stand from one hour at 50 mg/l free chlorine or two hours at 20 mg/l depending on the initial concentration1hr @ 50 mg/l or 2hrs @ 20 mg/l THERMAL DISINFECTION - Circulate water at >60oC for at least one hour flushing each outlet at full temperature for at least 5 minutes Chlorine Dioxide may also be used as a disinfectant and you should use the product as directed by your supplier Shower heads should be dismantled , cleaned, descaled and disinfected on aQuarterlybasis Third party contractors should provide evidence of competency of personnel and a certificate of completion detailing the chemical or temperature levels monitored throughout any disinfection process Cleaning & Disinfection

21. Alternative Control Methods • A number of alternative control strategies exist other than the temperature control methods described earlier but with all these methods it is necessary to establish a control level , achieve the control level, ensure the control level and record these levels • Careful consideration should be given to the Water Supplies (Water Quality) Regulations where the water being treated is also used for drinking, cooking or food preparation • The Regulations have no legal status to building owners, but do for water suppliers. However the Regulations have been written to protect human health. Neglect of these Regulations for potable water would be against all current advice. • Water not used for potable purposes would not be applicable to the above guidance • If you are in any doubt, the Drinking Water Inspectorate can give advice on 020 7082 8024

22. Alternative Control MethodsChlorine Dioxide • CHLORINE DIOXIDE – is a powerful oxidising biocide that is effective at levels of 0.1 mg/l and above. Care needs to be taken as the Drinking Water Inspectorate permits a combined concentration level of chlorine dioxide, chlorite and chlorate which must not exceed 0.5 mg/l. Contact your supplier for written guidanceon the effective use of their product • The Building Services Research and Information Association (BSRIA) have conducted research into the efficacy of chlorine dioxide to control legionella within hot and cold water systems • As with any control strategy, effective application and monitoring are essential to ensure it remains effective • Legionella sampling must be carried out on a monthly basis for the first year if temperatures are outside of ACoP L8 control levels • There are various methods for generating chlorine dioxide with each having their own advantages and disadvantages; • Chemical (2 or 3 pre-cursors) • Electro-chemical • Catalytic

23. Alternative Control MethodsChlorine Dioxide • Chlorine dioxide reserves need to be greater than 0.1ppm at outlets • In field test kits are available for both chlorine dioxide and chlorite. If the chlorine dioxide is being dosed to water which is to be used for drinking, cooking or food preparation, the product stream must be checked for chlorate formation. The manufacturers advice should be sought. • If the chlorine dioxide is used to dose the mains water line, appropriate backflow prevention devices should be fixed prior to the injection point. • Chlorine dioxide will gas off in a hot water system, so maintaining a residual may be difficult. Contact your supplier for written guidanceon the effective use of their product in hot water systems • The relationship between chlorine dioxide and redox is a tenuous one. Preferred methods of dosing are either via proportional injection or use of a chlorine dioxide specific probe. If redox is to be used, evidence must be sought from the manufacturer of the relationship between redox and chlorine dioxide levels on a similar system.

24. Alternative Control MethodsSilver/Copper Ionisation • SILVER/COPPER IONISATION - a powerful combination that is effective at levels of 0.02 mg/l of silver in softened water or 0.04 mg/l in harder water. Care needs to be taken if it may come into contact with drinking water as the Drinking Water Inspectorate has not approved the use of silver as a continuous disinfectant for water used for drinking, cooking or food preparation. Contact your supplier for written guidanceon the effective use of their product • The Building Services Research and Information Association (BSRIA) have conducted research into the efficacy of silver/copper ionisation to control legionella within hot and cold water systems • As with any control strategy, effective application and monitoring are essential to ensure it remains effective • Legionella sampling must be carried out on a monthly basis for the first year if temperatures are outside of ACoP L8 control levels

25. Alternative Control MethodsSilver/Copper Ionisation • Silver reserves need to be greater than 0.02ppm at outlets in softened water or 0.04ppm in harder water • In field test kits are available for silver. The manufacturers advice should be sought on which is best to use. • If silver/copper ionisation may come into contact with the mains water line, appropriate backflow prevention devices should be fixed prior to the application point. Drinking water should be taken from the mains water line prior to the backflow prevention device. • The efficacy of silver/copper ionisation is reduced in water with pH > 7.6 or in hard water which may cause the ions to precipitate out.

26. Other control strategies include ozone and UV light which have no residual effect but can be useful as point of use disinfectants. However, this is not likely to be cost effective for hot and cold building systems. Contact your supplier forwrittenguidanceon the effective use of their product Alternative Control Methods

27. Record Keeping[hot and cold water systems] It does not matter what monitoring activities are carried out or how successful they are, if they are not logged in a specific logbook or computerised system, they are not deemed to have been done at all ! Record systems should include the following information: • Details of the risk assessment • this must be current, including schematics and clearly defined lines of communication • Details of precautionary measures implemented • this is the information detailed in the written scheme • Monitoring, inspection, test and check results • a record of all results including signatures, dates and what was actioned when out of specification • a record of analyses (as appropriate) • an asset inspection record, including subsequent remedial actions • a record of cleaning and disinfection, including details of chlorination levels, temperatures (during pasteurisation) and certification • personnel training records - including this course ! Risk assessments & control schemes should be kept whilst current & for 2 years after that period. Monitoring results should be retained for 5 years.

28. Company Director System Managers E.g. Utility Managers Production Managers Laboratory Manager(s) Supervisors Water Treatment Providers Operators Record Keeping • You should be aware of the lines of communication • You must report all matters and results promptly • Data must be inserted into the appropriate record systems ABC Limited Remember Outside contractors cannot take on your responsibility for health & safety, they can only act in an advisory capacity. They have a responsibility to give you best advice at all times. Example of typical reporting structure

29. You have completed the hot and coldwater systems study course Thank you for completing our study course, it should have outlined control of Legionella with specific regard to hot and cold water systems. We would recommend that you check what you have learnt by completing our interactive multiple choice questionnaire. This can be accessed by clicking on ‘finished’ below and then selecting the Legionella Awareness course test from the master menu. If you are successful you will get the opportunity to print a certificate, confirming your competence. Finished