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RepWars Briefing - Questions & Answers
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Question...
"Dear sirs or madam. We have a contaminated water system. Due to turbulation, poor circulation, fluctuation of water pressures, and operation or construction. I am not sure how bad it is, no one has been sick that I know of, yet. We would like to know of some ways to flush out a group of risers, and treat it with whatever we need to clear it up. Better, can you make some suggestions for us to follow. We are a ten story hospital with four wings and a lot of water risers. Thank you."
RepWars Reply...
It sounds like there's a job and a half in front of you... Hopefully this information will help...
I recommend that you first take samples from various outlets and have them tested by a lab to determine what kind of contamination you are dealing with.
Any sections that reveal health risk should be taken off line immediately.
To begin general disinfection of the piping, you may consider contacting a commercial plumbing contractor that has experience installing large domestic water piping systems. They should have the proper equipment and knowledge for flushing and disinfecting. You and your staff will have your hands full coordinating the effort. As each section is taken off line, you or the contractor should take the opportunity to remove any dead-legs or other piping arrangements that might contribute to future contamination. This is also a good time to install drain and isolation valves for future disinfection and servicing. Piping and components at the source of the facility's water supply should be disinfected first so that sections upstream are not re-contaminate . After each section is initially disinfected, take samples to a lab for re-testing. Repeat the process until all contamination is removed.
The following general information may be helpful:
The most common method of disinfection is filling piping with a 200 parts per million chlorine solution, letting it stand for three hours and then flushing with clean potable water.
Remember that chlorine is very volatile so it is dangerous to work with in confined areas. Make sure the work area is well ventilated.
Disinfect the other portions of the distribution equipment that may contribute bacteria to the water supply (pump, pressure tank).
Drain as much water from the system as possible. For systems with pressure tanks containing a bladder, the rubber air-water separator inside the tank could be damaged by the chlorine solution. Check manufacturers' recommendations to determine if the pressure tank should be bypassed. For pressure tanks without bladders, release the air so that the tank can be filled with chlorinated water. Drain water from the water heater so that chlorinated water can be circulated through the hot water pipelines.
Backwash and clean water softeners, sand filters and iron removal filters with a strong chlorine solution. Do not chlorinate activated carbon filters since these filters will remove the chlorine until they become overloaded. Activated carbon filters should be removed from the distribution system until after chlorine has been flushed from the system.
Determine the amount of chlorine product required for a 200 ppm solution:
Amount per 100 gallons of water...
Liquid Laundry Bleach (5.25% NaOCl) - 3 pints
Commercial Strength Bleach (12-17% NaOCl) - 1 pint
Chlorinated Lime (25% CaOCl2) - 11 ounces
Dairy Sanitizer (30% CaOCl2) - 9 ounces
High-test calcium hypochlorite (65-75% Ca(OCl)2) - 4 ounces
Chlorine compounds are volatile so they will degrade with time. Purchase only what you'll need and use it all. Always read and follow manufacturers' recommendations. When using chlorine bleaches, do not purchase bleaches that have scents or other additives.
The following online table provided by Johns Hopkins is a good resource for determining disinfection methods:
http://www.hopkins-heic.org/infectious_diseases/water_table.htm
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The following concerns Legionella and may be good to know:
Growth of Legionella -
Legionella may enter the system through the cold water supply and contaminate the system. In the case of warm water systems that circulate warm water and do not use thermostatic mixing valves, the risk of Legionella growth must be addressed by disinfection, combined with regular Legionella testing as a performance measure. Disinfection usually involves the use of one or more methods such as monthly heat disinfection, monthly chlorination, continuous low-level chlorination or UV treatment. Combinations of different disinfection methods should be considered as a way of minimizing the risks.
Where thermostatic mixing valves are used, the risk of Legionella growth must be addressed by the annual valve cleaning and maintenance. A program to monitor temperatures throughout the system can also assist in understanding of the system and may consequently allow actions to be taken to reduce the risks.
The hospital critical incident plan must deal with the potential for the system to become contaminated with Legionella and should describe in detail the procedure to be followed in that event.
Age and Complexity Older pipe networks are more likely to support Legionella because of problems such as corrosion. This risk needs to be considered in a risk assessment.
There is also an increased risk associated with a highly complex and lengthy network of pipes and heaters, when compared to simpler, shorter pipe systems.
These factors can only be addressed by:
Comprehensive reviews of the system including the examination and replacement of key components where appropriate.
More intensive environmental surveillance or disinfection systems.
Patient Mix - The risk of Legionnaires’ disease increases with the increasing vulnerability of the people who may be exposed to the aerosols from a shower. This may be addressed by strategies such as increased Legionella testing and rigorous disinfection.
Patient Management - Patient management in the context of warm water systems relates to minimizing the contact that high risk patients may have with showers from a contaminated system, until such time as the contamination has been eliminated.
Legionella Testing - Regulatory Compliance
The Health (Legionella) Regulations 2001 require that in the case of hospitals with warm water systems which provide overnight accommodation:
· At least two samples must be tested for Legionella every quarter for at least 12 months (minimum of 8 samples per year).
· If Legionella is not detected in any sample during the previous 12 months, at least two samples may be taken every 6 months for so long as Legionella remains undetected in the system (minimum of 4 samples every year).
However, where the method of disinfection in such facilities is by ultra-violet light, at least two samples must be tested for Legionella:
· At least monthly for 12 months (minimum of 24
· If Legionella is not detected in any sample during the previous 12 months, testing may be performed every 3 months, for so long as Legionella remains undetected in the system (minimum of 8 samples per year).
Health facilities such as day procedure centers, which do not provide overnight accommodation, are only required to sample for Legionella when the method of disinfection is by ultra-violet light. In such cases testing is required:
· At least monthly for 12 months (minimum of 12 samples per year).
· If Legionella is not detected in any sample during the previous 12 months, testing may be performed every 3 months for so long as Legionella remains undetected in the system (minimum of 4 samples per year).
These Legionella testing requirements do not apply to hot water systems supplying water above 60°C (140° F) directly to multiple thermostatic mixing valves.
Sampling Protocol In most warm water systems there are few if any control measures, other than monitoring the temperature of the water during heat disinfection or the level of chlorine in a continuous chlorination system. This contrasts with cooling tower systems, where there are typically a number of control measures that are relatively easily measured. As a result, the importance of Legionella testing as a performance measure becomes even more critical. As stated above, the Health (Legionella) Regulations 2001 require a minimum frequency of Legionella testing. However, the Department recommends that:
· The sampling frequency be increased to gain a more representative measure of the performance of the systems’ performance.
· A sampling protocol be developed.
The Department recommends the following basic components be included in such a sampling protocol:
Samples are taken of the water as it leaves showers and taps.
Sampling points are varied each time, so as to eventually take samples from all parts of the facility.
Higher weighting is given, resulting in increased sampling frequency, to high risk sites such as transplant and oncology units.
A sampling protocol should take into account the age, complexity and number of warm water systems and require additional samples where these factors point to increased risk.
Additional attention should be given to patient treatment areas with showers that are furthest from the heating or disinfection points.
Sampling frequency be specified in detail.
In relation to the sampling frequency, the Department recommends that:
In the case of hospitals with less than 500 beds, a minimum of at least 10 samples is taken over a six-month period, regardless of the method of disinfection.
In the case of hospitals with more than 500 beds, a minimum of two samples per 100 beds is taken over every six-month period, regardless of the method of disinfection.
Also, as with cooling tower systems, all warm water systems in a hospital must be regarded as having a high potential for the growth of Legionella and for cases of Legionnaires’ disease in high risk patients.
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