Photo: Greatal386 at English Wikipedia · CC BY 2.5Radon in Dalkey: an estimated 5.1% of homes are above the reference level
Landslide ground weighs most on Dalkey’s grade: with 4.6% of homes on it, it grades D: #114 of 116 in County Dublin. Flood counts only against a town, so its share of low-lying homes earns it no credit: radon and landslide ground set the grade.
What stands out about Dalkey’s hazards
From the EPA’s radon map, Geological Survey Ireland’s landslide map, the OPW’s flood relief schemes and our estimate of low-lying homes, below.
What Dalkey faces
Each hazard against its own yardstick; meters run from low to high on that yardstick.
Low-lying homes
By the coast
Radon
Landslides
Bathing water
Ground heights
Dalkey grades D for hazard risk
Radon, landslide ground and low-lying homes, each against Irish towns, then averaged.
Each figure is placed among Irish towns of 1,000 or more people; the grade averages the three, so a better place on each is a better grade.
Flood counts only against a town, never for it: Dalkey’s share of low-lying homes would have raised its grade, so it isn’t counted, and radon and landslide ground set it.
Its place: #114 of 116 in County Dublin and #297 of 321 Irish towns.
Less sure: The low-lying figure is our estimate from ground heights and the river map, not an official flood map. It can show a town is low-lying; it can’t show a town is safe.
Few of Dalkey’s homes stand low by a big river, lake or the sea
Low-lying homes, a TownRatings estimate from OPW and Geological Survey Ireland LiDAR ground heights and the EPA’s river map: not an official flood map. Smaller streams, drains and groundwater aren’t in this measure, so a low figure doesn’t mean a town never floods.
Share of each town’s homes standing low by big water, for the towns measured in detail. 43% have none; Dalkey has more than 45% of them.
| # | Town | People | Low-lying | |
|---|---|---|---|---|
| 1 | Finglas North Dublin | 9,805 | 0% | |
| 2 | Cabra West Dublin | 9,786 | 0% | |
| 3 | Kilmore Dublin | 9,786 | 0% | |
| … | ||||
| 14 | Killiney Dublin | 9,776 | under 0.1% | |
| 15 | Christchurch Dublin | 6,778 | under 0.1% | |
| 16 | Dalkey Dublin | 8,275 | under 0.1% | |
| 17 | Booterstown Dublin | 8,505 | 0.1% | |
| 18 | Tuam Galway | 9,647 | 0.3% | |
| … | ||||
| 39 | Baldoyle Dublin | 7,864 | 77% | |
| 40 | O'Connell Street Dublin | 6,749 | 100% | |
The 40 Irish towns nearest its size that are measured in detail.
Low-lying homes across County Dublin’s towns · 106 towns measured in detail
Dalkey ranks 37th of County Dublin’s 106 towns measured in detail, counting from the most low-lying homes.
Homes: OpenStreetMap buildings of 30 m² or more, not tagged as non-residential, in the town’s Census 2022 Small Areas. Heights: GSI Open Topographic Data LiDAR (OPW, TII and GSI surveys). Water: EPA river network (rivers of Strahler order 5 or more), lakes, estuaries and coastal waters.
Weather and flood warnings for Dalkey
Where to see the warnings in force, and what this page can’t count.
Met Éireann issues yellow, orange and red warnings for rain, wind and coastal flooding county by county; Dalkey is covered by County Dublin’s.
| Warning | What Met Éireann means by it |
|---|---|
| Yellow | Weather that isn’t unusual but can be dangerous in places: be aware. |
| Orange | Infrequent, dangerous weather that can put people and property at risk: be prepared. |
| Red | Rare, extremely dangerous weather: take action to protect yourself and your property. |
Met Éireann doesn’t publish an open archive of past warnings, so how often warnings have covered Dalkey can’t be counted here.
No OPW flood relief scheme protects Dalkey
The Office of Public Works’ completed flood relief schemes and the areas each one benefits (OPW open data, CC BY 4.0).
None of the OPW’s completed flood relief schemes has a benefiting area that takes in Dalkey’s homes. The OPW builds schemes where the risk to homes is greatest, so most towns have none.
In County Dublin, OPW schemes protect parts of 12 other places, including Dublin, Clonsilla, Sandymount, Mulhuddart, East Wall.
| Town | Scheme | Designed for | Homes behind it | Away |
|---|---|---|---|---|
| Bray Wicklow | Bray (River Dargle) Flood Relief Scheme | 1 in 100 | 5% | 9.0 km |
| Sandymount Dublin | River Dodder (Tidal) | 1 in 50 | 37% | 9.2 km |
| Ballsbridge Dublin | River Dodder (Tidal) | 1 in 50 | 32% | 11 km |
| Grand Canal Dock Dublin | South Campshires Flood Relief Scheme | 1 in 200 | 14% | 11 km |
| St Stephen's Green Dublin | South Campshires Flood Relief Scheme | 1 in 200 | 5.9% | 12 km |
| East Wall Dublin | Spencer Dock Flood Relief Scheme | 1 in 200 | 82% | 12 km |
4.6% of Dalkey’s homes stand on landslide-prone ground
Geological Survey Ireland’s landslide susceptibility map (1:50,000), read at every home.
Homes on ground rated high or moderately high
That is a higher share than in 98% of Irish towns; the median is 0% for County Dublin’s towns and 0% for Irish towns.
GSI rates ground from low to high by its slope, soil and rock. Most Irish landslides are on steep upland slopes and peat after heavy rain; a town on flat ground has almost none.
High means the ground could slide under the right conditions, such as days of heavy rain on a steep, wet slope; it isn’t a forecast that it will.
GSI landslide susceptibility, high and moderately high classes, share of the town’s homes on mapped ground (CC BY 4.0).
An estimated 5.1% of Dalkey’s homes are above the radon reference level
The EPA’s radon map: for each 10 km square, the estimated share of homes above the national reference level of 200 Bq/m³.
A square where 10% or more of homes are estimated above the reference level is a High Radon Area; 0% of Dalkey’s homes are in one. The map is an estimate by area: two neighbouring houses can differ a lot.
A test is the only way to know a home’s level: two detectors, left for three months in a living room and a bedroom.
EPA radon map of Ireland (10 km grid), averaged over the town’s homes (CC BY 4.0).
2 EPA-licensed sites within 5 km of Dalkey’s centre, none inside it
Factories, farms, power plants and waste sites that hold an EPA licence for their emissions, in Dalkey and around its centre.
| Site | Licence and activity | Away |
|---|---|---|
| Amgen Technology (Ireland) Unlimited Company | Industrial Emissions licence · chemicals | 2.7 km |
| embecta Penel Limited | IPC licence | 3.0 km |
| Ballyogan Landfill Facility Ballyogan Recycling Park | Waste licence | 6.1 km |
| Sleever International Limited | IPC licence | 6.8 km |
| Nypro Limited | IPC licence | 7.2 km |
| Sytheses Limited | Industrial Emissions licence | 7.7 km |
| Electricity Supply Board (Poolbeg) | Industrial Emissions licence · energy | 8.7 km |
| Starrus Eco Holdings Limited (Fassaroe) | Industrial Emissions licence · waste | 8.8 km |
| Activity | Sites |
|---|---|
| Waste | 7 |
| Not classed in the register | 4 |
| Energy | 3 |
| Chemicals | 1 |
Within 5 km: one under an Industrial Emissions licence and one under an older IPC licence.
An EPA licence sets what a site may release to air, water and land; it doesn’t mark the site as an accident hazard.
Sites holding dangerous substances in bulk come under the COMAH (Seveso) rules, but the HSA’s list of them has no open licence, so upper- and lower-tier sites aren’t counted here.
Source: EPA registers of Industrial Emissions, IPC and waste licences, sites licensed on 31 October 2026; distances in a straight line from the town’s centre.
Hazards in the places around Dalkey
Low-lying homes, radon and landslide ground, town by town.
| Town | Low-lying | Radon | Landslides |
|---|---|---|---|
| Dalkey | under 0.1% | 5.1% | 4.6% |
| Sallynoggin 13,245 · 2.0 km | 0% | 5.1% | 0% |
| Dún Laoghaire 17,994 · 2.1 km | 0.3% | 5.1% | 0% |
| Ballybrack 2,872 · 2.4 km | 0% | 5.1% | 0% |
| Killiney 9,776 · 2.9 km | under 0.1% | 5.1% | 6.2% |
| Cabinteely 15,864 · 3.4 km | 0% | 5.1% | 0.5% |
| Foxrock 12,163 · 3.9 km | 0% | 5.1% | 0.2% |
None of the measured places around Dalkey has many homes standing low by big water.
A dash under Low-lying: not measured there (too few homes with detailed ground heights), not none.
Get ready for what Dalkey faces
What to do, and what to ask before you move.
- Never walk or drive through floodwater: 30 cm of moving water can float a car.
- Move valuables, papers and medicines upstairs.
- Turn off gas, electricity and water if you’re told to.
- Test over three months, in a living room and a bedroom.
- Above 200 Bq/m³, a small sump and fan usually fixes it.
- The EPA sells radon test kits at radon.ie and lists registered contractors who fix high readings.
- Bring in or tie down bins, trampolines and anything the wind can lift.
- Keep away from coastal paths and piers while an orange or red warning is in force.
- Charge phones and keep a torch: fallen lines are the commonest storm damage.
- After the storm, report a fallen line to ESB Networks and keep well clear of it.
- Ask whether the home has ever flooded, and get a buildings insurance quote before you commit: flood cover isn’t always offered.
- Ask the seller or landlord for a radon test result, or test in your first months there.
- Check the address on floodinfo.ie: the OPW’s flood maps and its record of past floods.
- On a slope, ask the seller about cracks, drainage and any past ground movement.
What this data can and can’t tell you
- An estimate, not a flood map. Low-lying homes is a TownRatings modelling step: each home’s ground height from LiDAR, against the level of the nearest big river (Strahler order 5 or more), lake or estuary within 1 km, or the sea within 2 km. A home within 5 m of the water’s level, or below 4 m near the sea, counts.
- Flood counts only one way. A high share of low-lying homes lowers the Hazard risk Grade; a low share never raises it, because defences, small streams, culverts, groundwater and flash floods don’t show in ground heights. Below the national median a town scores as the median.
- Defences aren’t counted. Flood defences aren’t taken off: the OPW scheme that protects the most homes is shown instead, with its design standard.
- Measured where the heights are detailed. A town is measured, and counted, only where 80% of its homes stand on LiDAR heights. Elsewhere the page says flooding isn’t measured, never that the town is dry.
- Radon is an estimate by area. The EPA’s radon map gives the estimated share of homes above 200 Bq/m³ for each 10 km square, averaged here over the town’s homes. It says where to test, not what one house holds.
- The sea is measured by height. Homes count as low by the sea when their ground is under 4 m and within 2 km of coastal or estuary water; waves, surges and erosion aren’t modelled.
- Landslide ground is a map of where slides could start. GSI’s susceptibility map rates the ground itself; it doesn’t record past slides or say when one will happen.
- Bathing water is rated season by season. The EPA classes each identified bathing water from four seasons of samples; a rating says how clean the water has been, not how safe it is to swim.
- One town, many streets. Risk is street by street. Check a specific address on floodinfo.ie before you buy or rent.
Check any address against the OPW’s official flood maps on floodinfo.ie
Questions about flooding and hazards in Dalkey
Does Dalkey flood?
Smaller streams, drains and groundwater aren’t in that measure, so it doesn’t mean the town never floods. For a single address, the OPW’s official flood maps and past floods are on floodinfo.ie.
Is radon a problem in Dalkey?
The EPA’s map estimates that about 5.1% of homes around Dalkey are above the radon reference level of 200 Bq/m³: a higher share than in 56% of Irish towns. 0% of its homes are in a High Radon Area. The only way to know a house is a three-month test.
Is Dalkey at risk of landslides?
4.6% of Dalkey’s homes stand on ground rated high or moderately high for landslides. Most slides happen on steep slopes and peat after heavy rain.
Is Dalkey at risk from the sea?
About under 0.1% of Dalkey’s homes stand below 4 m within 2 km of the sea, against 0% standing low by rivers, lakes and estuaries. Coastal floods come with storm surges and spring tides; the OPW’s coastal maps on floodinfo.ie show the official picture.
How does Dalkey compare with the places around it?
Radon estimates around Dalkey run from 5.1% in Sallynoggin to 5.1% in Foxrock; Dalkey’s own is 5.1%.
Where is the nearest bathing water to Dalkey?
White Rock Beach, 1.2 km away, was rated excellent for the 2025 season; 12 identified bathing waters lie within 15 km.
How is Dalkey’s Hazard risk Grade worked out?
Dalkey grades D: radon, landslide ground and low-lying homes are each placed among Irish towns, and the grade averages them.
Flood: TownRatings’ estimate from ground heights, not an official flood map. Contains Irish Public Sector Data (Geological Survey Ireland, the Office of Public Works and the EPA) licensed under CC BY 4.0; Copernicus DEM © DLR e.V. and © Airbus, provided under COPERNICUS by the EU and ESA; © OpenStreetMap contributors. Radon and bathing water: EPA (CC BY 4.0). Landslide susceptibility: Geological Survey Ireland (CC BY 4.0).
Sources: low-lying homes: TownRatings’ estimate from GSI and OPW LiDAR, Copernicus GLO-30 and the EPA river network · radon: EPA radon map · landslides: GSI landslide susceptibility · bathing water: EPA bathing water quality · industrial sites: EPA licence registers · the grade: TownRatings, from these figures. Under Creative Commons Attribution 4.0 (CC BY 4.0).
Contains Central Statistics Office (CSO) data, Census 2022, and Tailte Éireann boundaries (CSO Urban Areas, Small Areas, local electoral areas, constituencies), under Creative Commons Attribution 4.0 (CC BY 4.0).