Unusual taste or smell

The taste and smell of the drinking water we supply to your tap should be acceptable with no abnormal change.

There are a number of different factors which can change the typical taste and smell of your water.

Bleach or disinfectant

If there is a faint taste or smell of bleach or disinfectant from your drinking water, this is most likely due to chlorine.

Chlorine plays an important role in protecting public health by killing harmful bacteria in our drinking water. This is a necessary disinfectant used worldwide across the water industry to help maintain a safe drinking water supply. Almost all water supplies have added chlorine and, as a result, the water from these supplies will have a slight chlorinous taste and smell. This is not harmful to your health.

If the taste or smell becomes significantly more noticeable than what you are used to, please contact us on 1800 278 278 and we will ensure it is promptly investigated.

Health implications

The level of chlorine in your water is carefully monitored and controlled to ensure it is maintained at levels that are not harmful to your health. Sometimes operational changes during the treatment process may result in a slight increase in chlorine levels in the supply and this may result in a change of the taste and smell of the water.

What to do

If the smell or taste of chlorine is stronger than normal, you should fill a jug with tap water, cover it and store in the fridge, preferably over night. This should reduce the smell and/or taste of chlorine.

Earthy or musty

Sometimes earthy tastes can develop in drinking water. This can be caused by one or more of the following.

Stale water

Drinking Water that has been sitting in the pipe for a relatively long time can develop a stale, earthy taste or smell. This is most likely to occur in long service connections or in buildings, such as apartment blocks, that have drinking water storage tanks.


There may be bacteria in your plumbing system causing the earthy or musty smell. If you suspect that this is the case (e.g. if your neighbours do not have the same issue) you should consult your local plumber for assistance.

Source water

In some cases, an earthy taste can originate from the source water. Growth of algae in the area where the water is abstracted may result in an earthy or musty taste / smell in your drinking water. This typically occurs in lakes or impounding reservoirs.

MIB and Geosmin

The presence of MIB or Geosmin in drinking water, while not harmful to your health, can cause an earthy or musty taste or smell. MIB is an abbreviation for 2-Methylisoborneol. These naturally occurring organic substances are produced by algae and filamentous bacteria in lakes, rivers, streams and reservoirs. It is typically seasonal in nature and limited in duration. Conventional water treatment processes do not remove MIB or Geosmin. 


Health implications

While the taste and smell can be unpleasant, drinking water with an earthy or musty taste is typically harmless. However, if your water develops an unexpected earthy or musty taste, you should contact Irish Water and we will immediately investigate the issue.

What to do

You may wish to speak with your neighbours to see if they are experiencing similar earthy taste / smell issues. Running the cold water tap in your kitchen sink for a few minutes may clear any stagnant water in your system. If the taste / smell does not improve after running the tap, you should contact Irish Water and we will immediately investigate the issue.

If you suspect that the source of the problem is within your plumbing system you should consult your local plumber for assistance.