Intro Text 

Irish Water has the responsibility for the testing of drinking water samples since 1st January 2014. Please contact them for further information on 1890 278 278 or www.water.ie/water-supply/water-quality



Descriptions of Sampling Locations

In compliance with EU Drinking Water Regulations, water samples for testing are taken at treatment works at various locations throughout the distribution network including at the actual point of use i.e. consumer taps.  Sample locations are chosen to be representative of water quality throughout the network and include private premises, public buildings and commercial premises. 

Test Results of Main Parameters

Monthly results of complaince for the main parameters for each water service can be accessed through the links below.  The number of Parametric Value Exceedances are tabulated by supply and parameter.  The table below explains the abbreviations used in the result tables, the significance of each parameter and the EU Limits.

Monthly results of compliance prior to 1st January 2014 for the main parameters for each water service area can be found in Related Documents. 

Guide Values for Main Parameters for DLRCC Public Water Supplies - see Related Documents.

Parameters and Limits for Compliance with EU Drinking Water Regulations - see Related Documents.




Parameter : Colour
Limit : Acceptable to consumers and no abnormal change

Colour in water is usually due to the presence of complex organic molecules derived from vegetable (humic) matter such as peat, leaves, branches etc.  While colour, in itself, is primarily an aesthetic parameter, it may indicate other problems with the water supply, particularly where the water is chlorinated.  In such cases, the formation of trihalomethanes may occur.


Parameter : Odour
Limit : Acceptable to consumers and no abnormal change


Parameter : Taste
Limit : Acceptable to consumers and no abnormal change


Parameter : Conductivity
Limit : 2500 μS cm -1 at 20 OC

Conductivity is a measure of the ability of water to conduct an electrical current, therefore conductivity is related to the ionic content of the water. The water should not be aggressive.


Parameter : Coliform Bacteria
Limit : 0 No./100ml

The coliform bacteria (previously known as Total Coliforms) are a group of organisms that can survive and grow in water.  They are a useful indicator of treatment efficiency and the cleanliness of the distribution mains.  Coliform bacteria can occur in sewage and in natural waters.  Coliform bacteria should not be present in water that is disinfected and their presence indicates that either disinfection has not been complete, that there is ingress into the watermains in the distribution network or that the sample point is contaminated.


Parameter : Escherichia Coli (E.Coli)
Limit : 0 No./100ml

The E.Coli bacteria is present in very high numbers in human or animal faeces and is rarely found in the absence of faecal pollution.  As such, its presence in drinking water is a good indication that either the source of the water has become contaminated or that the treatment process at the water treatment plant is not operating adequately.

C. Perf

Parameter : Clostridium Perfringens (incl. spores)
Limit : 0 No./100ml

Clostridium perfringens is a member of the bacterial intestinal flora of humans and therefore serves as an indicator of faecal pollution.  The spores of Clostridium perfringens are particularly resistant to unfavourable conditions in the environment and thus they survive for long periods.  As such, they can be useful indicators of water that is intermittently polluted.


Parameter : Fluoride
Limit : 0.8 mg/l in fluoridated supplies
          1.5mg/l in naturally fluoridated supplies

Fluoride arises almost exclusively from fluoridation of public water supplies and from industrial discharges, although it occurs naturally in quite rare instances.  Past health studies have shown that the addition of fluoride to water supplies at levels above 0.6mg/l F- leads to a reduction in tooth decay in growing children and that the optimum beneficial effects were thought to occur around 1.0 mg/l.  However, in light of recent international and Irish research which shows an increasing occurrence of dental fluorosis, the Forum on Fluoridation (2002) recommended the lowering of the fluoride levels in drinking water to a range of 0.6 to 0.8 mg/l, with a target of 0.7 mg/l.  

Local Authorities are legally obliged to fluoridate public water supplies.


Parameter : Turbidity
Limit : Acceptable to consumers and no abnormal change

The control of turbidity is one of the indicators of the efficiency of treatment at the plant.  Elevated levels of turbidity in the treated water indicate that the treatment process is not operating adequately.  It also provides a good indication of whether the treatment plant is capable of removing Cryptosporidium ocysts.


Parameter : ph - Hydrogen Ion Concentration
Limit : 6.5 to 9.5 pH units

Hydrogen ion concentration (pH) is a measure of whether a liquid is acid or alkaline.  The pH scale ranges from 0 (very acid) to 14 (very alkaline).  the range of natural pH in fresh waters extends from around 4.5 for acid peaty upland waters to over 10 in waters where there is intense photosynthetic activity by algae.  However, the most frequently encountered range is 6.5 to 8.0.  the control of pH is a critical component of water treatment and distribution, influencing the effectiveness of coagulation, disinfection and the concentration of plumbing materials (such as lead, copper and nickel) in the final product.  The water should not be aggressive.


Parameter : Nitrate
Limit : 50 mg/l

Nitrate in the environment originates mostly from organic and inorganic sources such as waste discharges, animal slurries and artificial fertiliser.  High levels of nitrate in drinking water may induce "blue baby" syndrome (methaemaglobinemia).


Parameter : Nitrite
Limit : 0.5 mg/l

Nitrites exist in very low levels principally because the nitrogen will tend to exist in other forms (such as ammonia).  Nitrite is an intermediate in the oxidation of ammonia to nitrate.  Nitrite is associated with methaemaglobinemia.


Parameter : Ammonium
Limit : 0.3 mg/l

Ammonium in water supplies originates from agricultural and industrial processes, as well as from disinfection with chloramines (a method of disinfection not in use in Ireland).  Elevated levels of ammonium may arise from intensives agriculture in the catchment of the water sources.  Ammonium is therefore an indicator of possible bacterial, sewage and animal waste pollution.  Ammonium in itself is not a health risk but the parametric value serves as a valuable indicator of source pollution.


Parameter : Aluminium
Limit : 200 μg/l

Aluminium is present in drinking water as a result of its use as aluminium sulphate (a coagulant) in the water treatment process, though can be naturally present in some waters.  Historically, there has been some concern about possible links between aluminium in drinking water and Alzheimer's Disease.  However, the WHO states that:- 

"On the whole, the positive relationships between aluminium in drinking water and Alzheimer's Disease which was demonstrated in several epidemiological studies, cannot be totally discounted.  However, strong reservations about inferring a casual relationship are warranted in view of the failure of these studies to account for demonstrated confounding factors and for the total aluminium intake from all sources".


Parameter : Iron
Limit : 200 μg/l

Iron is an abundant metal found in the Earth's crust.  It is naturally present in water but can also be present in drinking water from the use of iron coagulants or the corrosion of steel and cast iron pipes during water distribution.  Iron is an essential element in human nutrition.  The WHO (WHO, 2004) states that values of up to 2 mg/l (10 times the parametric value) do not present a hazard to health.  However, at levels less than 2 mg/l but above the parametric value, the colour of water may turn brown, become turbid or may deposit solids on clothes washed in the water or food cooked using water.

Supply Areas and Sources



Area Covered


Stillorgan Reservoir (primarily
Ballymore Eustace and 
Roundwood Water)

Blackrock, Booterstown, Clonkeen, Deansgrange, Dun Laoghaire Town (West of Marine Road), Foster's Avenue, Roebuck, Monkstown, Oatlands, Orpen, Pottery Road, Stradbrook


Ballyboden (Bohernabreena
& Ballymore Eustace

Balally, Braemor, Central Park, Goatstown, Kellystown, Kingston, Lakelands, Mount Merrion (South), Nutgrove, Orwell, Pine Valley, Sandyford Industrial Estate, South Avenue


Ballyedmonduff (Local



Glencullen (Local Supply)



Kilternan (Local Supply)

Glenamuck, Ballychorus



Roundwood Reservoir


Ardagh, Ballyman, Cabinteely, Cherrywood, Foxrock, Johnstown Leopardstown, Merville, Mullinastill, Old Conna, Ralahine, Shanganagh, Shankill, Stillorgan Village, Watsons, Woodbrook


Church Road (primarily
Ballymore Eustace & 
Roundwood Water via Stillorgan Reservoir)

Ballinclea, Ballybrack, Dalkey, Dun Laoghaire Town (East of Marine Road), Glasthule, Glenageary, Killiney, Loughlinstown, Mounttown, Sallynoggin, Sandycove.


Saggart (BME) (Ballymore
Eustace Water)

Ballyogan, Broadford, Clonskeagh, Dundrum, Kilcross, Llewellyn, Marley Grange, Milltown, Sandyford, Stepaside, Sweetmount.