Taste and Odour drinking water problems hit Dublin, but are common this year due to high temperatures

During October Irish Water were inundated with complaints that the water being supplied in Dublin and county Wicklow tasted and smelt earthy and musty.

Odour and taste problems  are a common complaint issue for water undertakers and it has been estimated that nearly all supplies will suffer from problems occasionally (Gray, 2008). Earthy/musty odours are the most common and are caused primarily by moulds and actinomycetes.  They tend to be found where water is left standing  in pipework but also when water becomes warm which is the possible cause this year in Dublin. These problems are generally arise due to plumbing issues or unlined boreholes, especially when the soil is waterlogged.  Blue-green algae is also a possible cause when water is supplied from reservoirs.

Vartry Reservoir Wicklow, source RTE News, (https://www.rte.ie/news/) 

The common compounds that fall into this tase/odour category include Geosmin, 2-methylisoborneol, 2-isopropyl-3-methoxy pyrazine mucidine, 2-isobutyl-3-methoxy-pyrazine and 2,3,6-trichloroanisole.
In the recent situation, Irish Water were able to identify the problem causing compound as 2-methylisoborneol or  MIB and indicated the source to be blue-green algae.   If you think methylisoborneol is a mouthful, its synonym is 1,2,7,7-Tetramethylbicyclo[2.2.1]heptan-2-ol.  It is a cyclic tertiary alcohol  with the chemical formula C₁₁H₂₀O and a molecular weight of 168.28 g/mol.



Although MIB is not harmful, it does have an unpleasant taste and as personal taste thresholds vary within the community, some are more effected than others with a small proportion unable to tolerate the taste. MIB gradually disappears especially as the water temperature falls, but is expensive to remove from drinking water supplies requiring tertiary water treatment using adsorption membrane filtration or advanced oxidation.  Slow sand filtration which incorporates a biological surface zone (schmutzdecke) are good at removing these organic odours but have been largely replaced with the more compact rapid gravity filters.

Gray, N.F. (2008) Drinking Water Quality: Problems and Solutions. Cambridge University Press. https://www.cambridge.org/ie/universitypress/subjects/earth-and-environmental-science/hydrology-hydrogeology-and-water-resources/drinking-water-quality-problems-and-solutions-2nd-edition?format=PB&isbn=9780521702539

 

https://www.kennys.ie/business-finance/drinking-water-quality-gray-nick-f-9780521702539

 

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