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Tiosan - Legionella Control
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The Shower Doctor is not only a specialist in Shower Spares, we are also a supplier of the Safewater system. The Safewater system is designed to provide disinfection of domestic water systems with a safe and easy to use chemical. The chemical is Tiosan and after a 24 hour treatment it is proven to remove all traces of biofilm and Legionella from a water system.
Legionnaires Disease: What is it and what causes it? The need for Tiosan: A recent report by the Building Research Establishment (BRE) has indicated that standard chlorinating of water storage tanks as practised by the water treatment companies does not get rid of persistent Legionella. This confirms the findings of BSRIA who reported that chlorine does not remove the biofilm where Legionella tend to live. Most tank disinfections carried out by water treatment companies are ineffective. The BRE Report also proved that Legionnaires' disease could be caught from the plumbing systems in private houses. They found that 15% of the houses they investigated had Legionella in their water systems.
Legionnaires Disease: What is it and what causes it? Legionnaires Disease is caused by a bacterium called Legionella pneumophila. Legionella is a common microbe and it is generally found in rivers, lakes and reservoirs, usually in small numbers but is only dangerous when present in a water aerosol, which can be inhaled. The bacterium can then enter the lungs where it proliferates causing a severe pneumonia. One thousand people are treated in hospital for the disease each year. In 12% of cases the disease can prove fatal. Pontiac Fever, and Lochgoilhead Fever are lesser forms of the problem caused by other species of the Legionella. Water systems, which allow Legionella bacteria to multiply and also produce an aerosol, are considered as high risk. Legionella multiplies best at temperatures around 37 Degrees C. It dies at temperatures above 60 Degrees C. A good source of nutrients also helps the bacteria to proliferate. This means that water-cooling towers, which operate with warmish water, and broadcast a water aerosol can be considered as high risk and many of the outbreaks where a number of people have been affected result from improperly treated cooling water. Legionella can also be present in the domestic water system of multi-occupancy buildings like hotels, commercial offices, nursing homes, and hospitals and there is a risk where people shower in water from systems where Legionella proliferation has taken place. In this situation a number of people are likely to be affected. A recent Government sponsored survey has indicated that sporadic (isolated) cases of Legionnaires Disease are caused by the presence of Legionella in the domestic water system of the patient's home. Legionella is a problem if it gets into a water system and is allowed to proliferate. L8 (HSE Book - Legionnaires Disease Approved Code of Practice & Guidance) gives guidance on how to stop the bug multiplying in water systems. Traditional methods have focused on ensuring that water is maintained at the correct temperature and that systems are disinfected periodically. It is for this reason that hot water in most buildings is held at a temperature above 60 Degrees C and hot water taps are labeled as scald risk. It is the disinfection of water systems, which has proven to be most problematic as the traditional disinfectants, chlorine and chlorine dioxide are not considered reliable in removing biofilm, and Legionella can persist after a disinfection using these chemicals. The Safewater system uses a chemical, which has proven efficacy against biofilm and therefore Legionella.
Biofilm can be considered as a microbiological layer, which develops on the internal surfaces of most water systems. The surface material is important as the biofilm will extract nutrients from the pipe wall. Plastic pipes allow biofilm to develop faster than metal pipes. The biofilm acts as a habitat for bacteria and pathogens like Legionella. Ordinary disinfectants like chlorine cannot penetrate and destroy the biofilm. Tiosan because of its unique chemical action can attack the biofilm and because of its effervescence (mechanical action) will literally blast the biofilm away from the pipe wall.
This system comprises a chemical Tiosan, some simple measuring techniques, training, information and access to laboratory facilities. The system is designed to provide disinfection of domestic water systems with a safe and easy to use chemical. The system gives training on L8 (HSE Book - Legionnaires Disease Approved Code of Practice & Guidance) using courses and an interactive CD ROM.
Tiosan is a formulation developed in Holland as a disinfectant. The chemical is based on hydrogen peroxide, which has been stabilised and catalysed by colloidal silver in minute quantities. Tiosan is based on a chemical, which has approval from the Secretary of State for the Environment for use in potable water systems in the United Kingdom. The formulation has proven efficacy against biofilm because the formulation can attack biofilm chemically and mechanically. Extensive testing on the continent has shown that a 24-hour treatment at 50 ppm hydrogen peroxide will remove all traces of biofilm and Legionella from a water system. The Safewater System uses 75 ppm to ensure the water system can be used over the 24 hour period. A second treatment 6 months later will ensure that the system remains free of biofilm. Treatment using Tiosan depends on maintaining an average of 50 ppm hydrogen peroxide over 24 hours. This means that water can be used for washing hands and flushing toilets but not for running baths or washing cars as this would cause dilution of the chemical. From a practical viewpoint the chemical should be added to water systems immediately after morning baths in a nursing home or after 9 am in most hotels. In situations where it is not practicable to ensure minimal dilution viz small storage tank coupled with large systems throughput, Tiosan should be added over 24 hours to the system using a small timer controlled pump.
Tiosan is based on hydrogen peroxide, a chemical which is formed in the cells of the human body to protect the cells from attack by bacteria or viruses. Bacteria and viruses are sufficiently clever to mutate to fend off attack by hydrogen peroxide. They do this by emitting enzymes, which prevent the active parts of the hydrogen peroxide from getting through to kill them. In our formulation the silver reacts with the enzymes allowing the hydrogen peroxide to attack the bacteria.
How to Disinfect a Domestic Water System Background Information Tiosan will remove biofilm and therefore all Legionella from a water system providing it is applied at the correct concentration and is allowed to contact every part of the water system (no dead legs). Houses built over the past 20 years do not present a Legionella risk because they do not have water storage tanks, or they have properly constructed tanks which have secure lids, have good front to back circulation and have screened overflows. Method Statement This method statement assumes that the system starts at the water storage tank which supplies all the domestic water to the premises - the hot water via a calorifier or some other water heating device, and the cold water to downservices. The water storage tank should be given a preliminary disinfection. Calculate the size of the water tank and multiply its volume by 1.3. From the Safewater Chart (see Table 1 at the end of this booklet) calculate the volume of Tiosan, which needs to be added to give 75 ppm hydrogen peroxide. Add this volume to the water storage tank and mix well into the water. Drain the water through the taps in the premises, which are furthest away from the tank to ensure that the treated water contacts all the pipework. (please note that it is important that dead legs are found and, if possible, introduced into the main system flow or purged through with treated water). Check the water leaving the furthest tap (hot and cold) until the presence of hydrogen peroxide is detected. When a level of 75 ppm hydrogen peroxide has been obtained on a test strip, close the taps and retain the treated water in the pipework. 75 ppm hydrogen peroxide is represented by a dark blue colour on the test strip. This ensures that the water in the system remains safe to drink should anyone inadvertently drink the system water while the disinfection is taking place. The hot water system is particularly prone to harboring Legionella and care should be taken to ensure that there is Tiosan throughout the hot water system. Check drains from calorifiers and a selection of taps to ensure that there is sufficient Tiosan in the system. If the tank can be cleaned, drain the tank, or pump out the remaining water using a submersible pump, taking care to ensure that there is sufficient local drainage to cope with the flow. Clean the tank. This will mean getting into the tank, and cleaning the walls and floor of the tank. Plastic tanks may only need a wipe down while metal tanks may have to be scraped and cleaned with a pressure washer. Wet Vacs are usually employed to remove debris and water from the bottom of the tanks. When the tank is cleaned it should be filled with fresh water. The volume of Tiosan, which was added earlier should be added to the water in the tank. Check outlets over 10 minutes and if less than 75 ppm detected add more Tiosan until 75ppm is obtained consistently. The water in the outlets should continue to show a level of 75ppm hydrogen peroxide at the taps. In many buildings it is not possible to clean and disinfect the water storage tanks as they cannot be taken out of service. The procedure outlined above can be carried out without the tank clean. Tiosan can be added to the tank drawn to the furthest outlets until a reading of 75ppm is obtained. This procedure will remove all biofilm from the system and remove persistent Legionella.
Tiosan is, we believe, the best chemical currently available for dealing with the Legionella / Biofilm problem. It will work well providing the correct concentration of the chemical reaches every part of the water system. Before applying Tiosan you should check the water system for obvious dead legs - look out for areas where the pipework has been modified and a section of pipe still has water in it but is not part of the main flow. In industrial premises look out for duty/standby pumps where one pump is used and the other is valved off. Look out for washing machines and dishwashers, which are rarely used. The pipework connecting these to the main flow will be full and may have been static for many weeks. It is obvious that Tiosan cannot get into dead legs. Where possible open the flow to dead legs eg. allow hoses to run. If all dead legs can be eliminated Tiosan should remove Legionella from a water system. Regular applications of Tiosan will ensure that the biofilm will not return. We would recommend treatment every 6 months if the water distribution pipework is mainly metal and every 4 months if the water distribution pipework is mainly plastic. Good Legionella control is down to good plumbing practice and compliance with the Water Supply (Water Fittings) Regulations 1999. This includes the prevention of backflow, the use of approval materials for pipework, water fittings and jointing materials. General issues of design, sizing, layout, construction and commissioning are discussed in BS6700:1997. Hot and Cold systems should be designed to aid safe operation by preventing or controlling the growth of Legionella and to allow easy cleaning and disinfection. Appropriate tests should be carried out to validate the efficacy of the process. Natural rubber, linseed oil based jointing compounds, and fibre washers should not be used, use only WRC approved materials. Use low corrosion metals if possible. Ensure water storage tanks are covered with a well fitting lid, with insect screens fitted to any pipework open to the atmosphere. Multiple linked tanks should be avoided. The diaphragms in accumulator vessels should be accessible for cleaning. Point of use water heaters with minimal water storage should be fitted. Minimise the storage of cold water. Cold-water storage tanks should be sited in a cool place and insulated to protect from extremes of temperature.
1. Measure the water storage tank and calculate capacity. 2. Calculate system capacity = 1.3 * tank volume Note: This does NOT take into account any other water storage capacity which must be added to the system capacity. 3. Add volume of Tiosan as recommended by the chart (Table 1 below) to the water in the tank and mix well. 4. Draw water to the furthest taps (hot and cold) and test until 75ppm hydrogen peroxide is detected at the outlets. 5. If carrying out a tank clean, after one hour drain the tank (not the system) clean the tank and refill to 75ppm with water/Tiosan. 6. Check list of other considerations.
Volume of Tiosan to be added to Water Systems to give a level of 75ppm Hydrogen Peroxide
This table is based on a Tiosan level which conforms to EC Drinking Water regulations and meets the European norms to kill Legionella. Remember Calculate the nominal volume of the system. Measure the height, length and depth of the tank in metres. Multiply together and this will give a nominal volume in cubic metres multiply by 1000 to bring the answer to litres. For example
Plumbers could offer a standard disinfection in any house where they are working. It should be pointed out that full blown Legionnaires Disease is rare (probably only 1000 cases per annum in the UK) but that lesser forms like Pontiac Fever and Humidifier Disease which have flu like symptoms are a lot more prevalent. At a time when people are concerned about all sorts of health related issues, they should be alerted to the fact that their domestic water system could present a serious health risk. Tiosan disinfection is simpler, faster and more effective than standard chlorination making plumbing companies very competitive when quoting for this type of work.
Tiosan Pack Size 1 litre bottle Tiosan Pack Size 4 x 5 litre cans (Discount available for bulk orders) Testing Systems Information - CD Rom: Testing your knowledge of L8 and helping you to £25 produce a log book. All prices exclude VAT and delivery. To order, please call our office on 0131 538 4343. If you have any queries, please email mail@showerdoc.co.uk
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Tel: 0131 538 4343 - Fax: 0131 477 2623 - info@showerdoc.co.uk |
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