Trihalomethanes THMs

Cathal Walsh
Content Creator
Wednesday, 5th June 2019
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Water flowing out of a tap into a glass

Table of Contents

Maximum amount allowed in water: 

100 μg/litre

What are they?

These are chemical compounds formed during the water disinfection process when chlorine [Cl] or bromine [Br] combine with carbon [C] and hydrogen [H]. As the EPA states “As the EPA states, ‘there is a fairly straightforward relationship between the degree of colour in water prior to chlorination and the quantity of THMs present following chlorination.

How do they get into water?

By their nature THM’s are never found in the source of water. THM’s are created in water as a result of the disinfection processes that carried out by the local council in municipal water treatment facilities. There is however as the EPA states a relationship between the colour of the source water and the level of THM’s in the end product.

How do they affect our health?

THM’s are central nervous system depressants and are known to be toxic to both the liver and the kidney.  The international agency for research on cancer has concluded that Choliform is most likely carcinogenic.  These THM’s are most likely to enter the body through drinking contaminated water or inhaling vapour from the water when bathing or showering.

How can I find out if they are in my water?

By taking a water sample and sending it to an accredited laboratory for analysis. To test for THM’s follow the link here

How can I remove THM’s from my water?

THM’s can be removed from water if either a reverse osmosis system, a carbon filter system or an ion exchange system fitted to the main tap of the house.

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