Legionnaires Disease is a potentially fatal form of pneumonia caused by the inhalation of small droplets of contaminated water containing the Legionella bacterium. But what does this mean exactly and are tenants really at risk? The simple answer is yes; not only tenants who rent properties but anyone who lives in a property which contains a water system (most likely every residential premises in the country!).
How do people contract Legionnaires Disease?
In order to be contaminated with the disease firstly the Legionella bacterium would need to be present at a dangerous level within the water system (such as boiler). Nearly every water system will show traces of Legionella in it, however an unsafe level would be above 100 C.F.U’s or Colony Forming Units to you and I! Once a dangerous level of C.F.Us has built up in a water system the bacterium then needs to get itself into the lungs and this generally happens by the inhalation of droplets of contaminated water, which in domestic properties can happen via items like spray taps and shower heads. However it can also be contracted through contaminated liquid entering the lungs via the trachea or windpipe (going down the wrong way).
How does Legionella become a problem?
As I mentioned above nearly every water system in residential properties will test positive for the Legionella bacterium however if it is under 100 C.F.Us it is not regarded as a risk.
Before I move on I would like to stress this point as there are some companies offering to carry out Legionella risk assessments on behalf of landlords and offering to do a water sample, which is something that is really not required in a domestic property. I truly believe that in most cases this sampling is being offered so that test results show Legionella in the system and that remedial works (disinfecting of water system etc.) can be sold to landlords. So please be wary and ask to see test results prior to having any costly, unnecessary works carried out. Back to how Legionella becomes a problem. How do we get high levels of Legionella in a water system? The answer is a combination of temperature, food and time.
Legionella thrives in a temperature range of 20°C to 50°C with the range of 35°C to 40°C favouring significant growth. Below 20°C the bacterium remains dormant and will not actively multiply and above 50°C the bacterium starts to be killed off.
Nutrients in the water from sediment, sludge, scale and other materials within the system are a food source for the Legionella bacterium. A few examples of where these nutrients are likely to be are: scale on shower heads or taps, in a cold water storage tank that is not cleaned and maintained or within a hot water storage cylinder that is not cleaned and maintained.
The water then needs to be still for a period of time so the bacterium can multiply and thrive to a dangerous level. This could happen when people go away on holiday or have some outlets within their property that they may not use regularly or just a vacant period for a rental property whilst new tenants are being found. This allows the water to stagnate, rise in temperature where it’s sitting in the pipe work and not being removed from the system (via flushing the toilet, running a tap etc).
So what can we do to manage the risk and control it? Simple, keep the hot water hot, keep cold water cold, keep the water moving around the system and keep all parts of the water system clean.
Landlords have a legal responsibility to have a Legionella risk assessment carried out on their rented premises. It is possible for knowledgeable landlords to carry out the risk assessment themselves if they can access the right test equipment. All information relating to what should be within the risk assessment can be found on the government’s HSE website and there is no formal qualification required but should a tenant contract Legionella disease and the risk assessment is found not to be “not up to standards” it would likely leave the landlord with some headaches, so I would always recommend outsourcing the risk assessments if you are not 100% confident in carrying them out.
Once the risk assessment is carried out I would recommend the landlord makes sure it includes everything it needs to include before filing it away and assuming its sorted. All this info can be easily found on the HSE website (start here and navigate your way around http://www.hse.gov.uk/legionnaires/legionella-landlords-responsibilities.htm) If you believe something has been missed from the risk assessment then always question this with whoever has carried out the assessment.
Once the risk assessment has been carried out then any problems found should be addressed, assuming it is economically viable. In domestic properties this tends to be things like: dead legs (a run of pipe work that is no longer in use or capped off), water temperatures not being within a safe range or problems with the cold water storage tank (no lid, soiled inside etc). Once addressed the risk assessment should be updated and a written scheme of control should be put in place for the property. The written scheme of control does not need to be costly to the landlord or inconvenient to tenants, simple things like ensuring your tenants keep all shower heads and tap heads clean, letting you know if the hot water isn’t hot enough or the cold water is warmer than they think it should be, flush through any unused outlets at least once every 7 days (by flushing I simply mean running the taps for 2mins or flushing a toilet twice) and letting landlords know if they are going away for a period longer than 7 days so flushing of the entire system can be arranged on the tenants behalf. TMV’s (Thermostatic mixer valves) often found on showers should also be cleaned and maintained and this is something that can be done by most plumbers or heating engineers during the yearly landlord gas safety inspection.
So in a nutshell Legionella disease is a genuine risk and landlords that have not yet arranged for a risk assessment to be carried out on their premises should bite the bullet and nip it in the bud at the earliest opportunity.
Blog written by Daniel Coghill of Advance Plumber Solutions
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