In this article the industrial water specialists at Water Treatment Services investigate the link between legionella, hard water and limescale; asking the question… does hard water increase the risks from Legionella bacteria both at home and in the workplace? The guide explains what hard water is and how it can cause problems in water systems, where it can be found in the UK, if the build-up of scale or limescale increases the risks posed by Legionella bacteria, and what can be done to control its impact.
What is the link between hard water, limescale and legionella?
Most of us are aware that the water which comes out of our taps varies from region to region throughout the UK.
One of the most common of these variations is the “hardness” or “softness” of the water.
The levels of water hardness are mainly down to the chemical make-up and type of rock which the water flows through or over on its way into our homes and businesses.
Most of us are also aware that hard water can cause the build-up of limescale in our water systems and appliances including kettles, washing machines, dishwashers, and shower heads.
This build-up of scale or limescale usually shows itself as a very hard white or off-white coating that starts to cover the internal surfaces of appliances, on shower heads, taps and other water outlets.
From a business perspective however, there are other potentially more serious issues that also need to be considered whether your water is soft or hard.
One of the main issues that needs to be taken in to account is that Legionella bacteria are known to form more readily in hard water than in soft… and this can have important water safety implications for businesses.
What is hard water?
Put simply, hard water is defined as water which contains high levels of dissolved minerals, in particular calcium and magnesium.
Hard water is water which contains high levels of dissolved minerals, in particular calcium and magnesium
Water picks up these trace elements of calcium and magnesium after rain water falls onto the ground, drains into the watercourse and then flows onwards into rivers, streams and reservoirs.
Soft water is different in that it doesn’t contain all of these minerals, or has them at much lower concentrations.
Is hard water dangerous to drink?
When it comes to drinking water, some people prefer harder water for drinking as it has far greater levels of dissolved minerals in it.
Softened water that’s been treated on the other hand, due to the levels of sodium, may sometimes have a slightly salty flavour which many people dislike.
Despite the apparent taste benefits of hard water from a drinking point of view, it can cause problems elsewhere in the water system and it’s these that we will look at here.
The impact of hard water and scale on water systems, appliances and equipment
Hard water can impact on all sorts of water systems, appliances, and industrial plant and equipment by leaving an unsightly coating or scum on surfaces.
Hard water is most evident when it forms limescale on the heating elements of kettles and irons, and on taps and shower heads, meaning you have to take steps to clean and descale them regularly.
Hard water doesn’t just affect smaller appliances though; it can also build up inside washing machines, dishwashers, and even inside your central heating boiler.
It is estimated that in the UK hard water costs on average £60 per year for every household to repair their appliances which have been affected.
Hard water, soap and detergents
Additionally, hard water might mean you get out of the shower with hair feeling no cleaner than when you went it, or it may make your hair and skin look dull and aged.
The main reason for all of this is due to the way soap reacts when it comes into contact with calcium or magnesium salts in your water.
Soap doesn’t lather as well in hard water, and doesn’t clean as efficiently.
This is the case whether you’re talking about lathering up soap to wash your hands, or trying to clean the inside of a central heating system or cooling tower.
Where are the UK’s hard water areas?
Geography and geology will define the harness of your water, and in the UK there is a definite east/west split.
Most of Scotland, Wales, Devon and Cornwall, and the North West of England tend to have soft water.
Hard water is generally found south of Leeds and east of Bristol, and is a problem in major centres of population such as London, Birmingham, Nottingham and Leicester.
There’s not much any of us can do which will affect the local geology and change the type of water flowing from your taps.
The northern and western parts of the country have a geology based on granite, whereas the further south and east you go, the predominant rock types tend to be limestone or chalk.
What is the link between legionella, hard water and limescale?
For many people soft water is better for many things, from your skin and hair to your plumbing systems, domestic appliances, boilers, and industrial plant and equipment.
Another upside to using soft water is that bacteria tend to favour hard water conditions because of its ability to form scale or limescale on surfaces and inside water systems.
That doesn’t just include Legionella bacteria, it also includes a whole host of other bacteria including pseudomonas and other unpleasant waterborne pathogens.
On the other hand, if you live or work in a hard water area, the growth of legionella on limescale deposits forming inside water pipes and water tanks, heaters, taps and shower heads can be a much more serious issue than in soft water areas, with all other factors remaining constant.
This is because hard water has greater levels of calcium and magnesium than soft water and these minerals cause scale to accumulate on the internal surfaces of water pipes and equipment.
As limescale builds-up on the inside surfaces of pipes, tanks and appliances it creates a rough, uneven surface with lots of tiny cracks, holes and fissures which allow bacteria to cling to, grow and multiply.
Researchers have confirmed this phenomenon in laboratory tests and have shown that biofilm find it difficult to build up on smooth surfaces that are without cracks and fissures… however, add in hard water and scale, and this all changes.
If you also consider water systems where dead legs and areas of poor or low water flow exists – which are just perfect breeding grounds for bacteria – the potential legionella problem multiplies further.
However, in order for legionella and other bacteria to multiply to problem levels it doesn’t just need hard water… it also needs a ready supply of food and nutrients in the form of algae, rust, scale or sludge.
How to identify limescale and so control legionella
Limescale is a solid white or dirty off-white deposit of magnesium or calcium salts which looks and feels like rock… it’s incredibly hard.
It tends to form around warmer areas of a water system including heat exchangers, like the element of your kettle, or inside a boiler on the heat exchanger surfaces.
As limescale builds up, the rate of water flow inside pipes can become restricted, equipment can become clogged and heat exchanger surfaces stop working efficiently reducing heating or cooling performance, and increasing energy costs.
Are scaled showerheads a legionella risk?
One of the main risk areas in both domestic and commercial settings is shower heads, which are present in the home but also found extensively in higher risk facilities such as care homes and hospitals too.
Legionella bacteria can start to grow in scaled showerheads, and as people in hospital or care homes already have health issues, they’re more likely to fall ill too.
Regular descaling of shower heads and making sure they are sanitised correctly will help you keep on top of the risk.
The most effective approach to deal with the risks from legionella in hard water areas is to take steps to control the scale in water systems so they are kept clean and free from limescale build-up.
One way of going about this is to eradicate the possibility of limescale growth by softening the hard water using a water softener.
Reducing the impact of hard water
Whatever type of hard water softening solution you opt for, the basic principle is the same, to work out when to add softening ingredients into the system, and at what levels.
Depending on your water system, you may also choose to add in specialist water treatment chemicals such as biocides, scale inhibitors, corrosion inhibitors or dispersants.
Other ways of combatting hard water might involve electricity or magnetism to dissolve the minerals in the water, which has been proven to be an effective treatment too.
Using water softeners to control limescale… and legionella
A more conventional method of controlling the build-up of limescale is to use water softeners which are based on sodium ion exchange.
This type of water softener is designed to remove the hard water ions which cause the damaging effects and make the water softer.
Water softening systems are generally low-maintenance, just requiring regular cleaning and topping up with the special water softening salts, and regeneration of the resin.
Specialist water management and legionella control solutions
Water Treatment Services offer a comprehensive range of high performance solutions for the pre-treatment of industrial and process waters including the design, installation and maintenance of water softeners. We are also expert in the management of legionella risks and support businesses and those responsible for the safety of engineered water systems in the workplace.
Find out how our engineering expertise can help you manage your water systems, maintain regulatory compliance and so keep people safe.
With offices in London serving the South and South East England, Manchester (North West), Birmingham (Midlands), Bristol (South East England and Wales), Leeds (North and North East) and Glasgow (Scotland), supported by regional teams of specially trained engineers, water specialists and technicians we offer cost effective water management solutions to businesses throughout the UK and Internationally.
Contact us today to learn how our expert water management solutions can help you.
Learn more about our solutions for the pre-treatment of hard water including commercial water softeners