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What is chloramination?
Understanding chlorine and drinking water
Chlorine has a bit of an image problem.
Here’s how…
How does chlorine actually kill off microbes?
Chlorine is a highly effective oxidising agent. Without getting too deep into the chemistry, that means it can react with bacteria, viruses and other nasty microbes to destroy them
The chlorine effectively changes the molecular makeup of the microbe cell; which not only shuts down the functions of the microbe’s components, but also breaks down the outer cell wall holding all those components in.
Eventually, the damage is done. The microbe is effectively destroyed and rendered completely harmless.
What causes that notorious ‘swimming pool smell’ in chlorine?
Believe it or not, chlorinated water alone doesn’t actually have a strong smell.
When you visit a public swimming pool and smell that familiar odour, what you’re actually smelling is chloramine (aka ‘combined chlorine’).
Chloramine is a compound that forms when chlorine reacts with ammonia. In swimming pools, organic matter in the water – such as swimmers’ sweat, skin cells, and the remains of the microbes the chlorine has killed off – provide the fuel to turn chlorine into combined chlorine.
The more chloramine in the water, the stronger the smell.
Too much chloramine also causes the eye and skin irritation that many swimmers are familiar with; another thing that chlorine often gets the blame for!
What is chloramination?
Not all chloramine is an unwanted byproduct produced from nasty organic matter. Water companies actually use combined chlorine – this time prepared with pure ammonia – as a secondary disinfectant for drinking water.
It’s less harsh than standard chlorine, but also protects the water for longer. The process of using chloramine to treat drinking water in this way is known as ‘chloramination’.
Many UK water companies will use standard chlorine (known as ‘free chlorine’) to treat the water at their facilities, then add a small amount of ammonia to leave a chloramine residual flowing through the distribution system.
The chloramine naturally disappears over several weeks; but since the supply keeps bringing new chloramine into the distribution system, your drinking water always remains protected from nasty pathogens.
Why doesn’t chlorine and chloramine in drinking water harm us?
You might have heard that chlorine is actually highly toxic. That’s certainly true of chlorine gas; but chlorine or chloramine in your drinking water is safely dissolved within the water.
Not only that, but the actual amount in your drinking water is extremely low. In the UK, a whole litre of tap water contains just half a milligram of free or combined chlorine.
For reference, a whole milligram makes up just one thousandth of a gram. (It’s a bit like taking a raisin and chopping it up into a thousand equally sized pieces; imagine how small just one of those pieces would be!)
The World Health Organisation recommends no more than 5 milligrams of chlorine for disinfecting drinking water, so our drinking water is well within safe limits.
What is new mains chlorination?
While free or combined chlorine water treatments work to keep our water safe, extra precautions need to be taken when new pipework is installed to prevent pathogens from entering the water supply.
Water companies will usually insist that any new pipes are fully disinfected and tested before they’ll allow a connection to the mains distribution system.
New mains chlorination is the process of filling a new pipework system with a chlorine solution to kill off any nasty microbes.
This solution typically contains a much higher dosage of chlorine than you’ll find in drinking water, in order to ensure the new pipes are completely sterilised.
After the solution has been flushed out, bacteriological testing is carried out to check for any remaining microbes; and a fully clean pipework system will be issued with a chlorination certificate, which enables it to be safely hooked up to the mains supply
Find out more about new mains chlorination in our guide to chlorination certificates – and if you’re looking for microbial water testing or water treatment services in the south, Dyanmika’s team of UK water specialists are here to help.
Call us on 03333 22 0800 or contact us online to discuss your requirements.
For more information on What is chloramination? talk to Dynamika UK Ltd