Flood, Water Quality, and Beaches: The Environmental Profile of Irish Property Areas

Buyers ask three environmental questions about a property: does it flood, is the water clean, and how far to a decent beach. The answers to all three are in public datasets — OPW flood maps, EPA water-quality monitoring, and the Blue Flag / Green Coast beach registry — but they're spread across three government websites that don't talk to each other. We pulled them together, spatially joined them to 60,522 recent Property Price Register sales, and built an Environmental Score for every Irish Eircode area with enough sales to rank. Here's what the data says.

How the score works

The score combines three public datasets — nothing proprietary, nothing modelled. For each Eircode routing key we compute the percentage of recent sales that sit inside an OPW flood zone, the EPA water-quality status of the nearest monitored river/lake, and the straight-line distance to the nearest Blue Flag beach.

• Flood exposure (50 pts). Percentage of recent sales in the area that fall inside an OPW CFRAM flood zone (fluvial or coastal, 100-year return period). 0% → 50 pts; 1–3% → 40; 3–7% → 25; 7–15% → 10; 15%+ → 0.
• Water quality (30 pts). EPA status rating of the nearest monitored waterbody. High → 30; Good → 25; Moderate → 15; Poor → 5; Bad → 0.
• Blue Flag beach proximity (20 pts). Distance from the area centroid to the nearest Blue Flag or Green Coast beach. Within 3 km → 20; 3–10 km → 12; 10–25 km → 5; beyond 25 km → 0. This rewards coastal amenity; landlocked areas are capped at 80 on the composite, which is a deliberate trade-off.

The two outliers: Dublin 2 and Ashbourne

Two areas dominate the wrong end of the flood ranking by a wide margin:

For every other routing key in our 126-area sample, flood exposure is under 3%. These two are not in the distribution — they are the distribution.

The explanations are geographic. Ashbourne sits on the Broadmeadow River floodplain — the town has documented surface-water and fluvial flood events, and the CFRAM 100-year model extends across much of the residential grid. Dublin 2 sits on the lower Liffey, where the CFRAM 100-year scenario combines riverine flood with a coastal tidal surge. Much of the city centre (including much of Temple Bar, the quays, and the Docklands) falls inside that combined extent.

This does not mean every property in these areas is in immediate danger. A “100-year flood zone” means a 1% annual probability event under the CFRAM model — a statistical risk, not a schedule. Many properties in these zones sit behind flood defences or above predicted water depths. But the zone status matters for insurance (Flood Insurance Association pricing differs significantly inside vs outside), for future risk under climate change (the modelled envelope grows), and for resale liquidity (buyers increasingly check OPW maps).

The next 8 most flood-exposed areas

Beyond D02 and A84 the distribution gets much more gradual. The third-most-exposed area (P72, Macroom) is at 2.7%.

Notice how many of these are river towns. Macroom on the Sullane, Clonmel on the Suir, Wexford on the Slaney, Ennis on the Fergus, Waterford on the Suir. If you're buying in a town named after or built beside a river in Ireland, “check the OPW flood map” should be a default part of the due-diligence checklist.

Water quality — a different map

The water-quality picture cuts differently. The EPA monitors 4,840 waterbodies under the Water Framework Directive, assigning each a status of High, Good, Moderate, Poor or Bad. The nearest monitored waterbody to a property is a reasonable proxy for the background water quality in the area — it doesn't tell you about drinking water (that's treated before it reaches the tap), but it does tell you about the stream at the end of the road and the river you might swim in.

Areas where the nearest monitored waterbody is rated “High status” — the top EPA category — are rare. In our sample the areas with a nearest-High waterbody inside 5 km are all in the south-west: West Cork (P75 Bantry area, P85 Skibbereen/Clonakilty hinterland), south Kerry (F23), Connemara (F45), and a handful of upland Wicklow and west Offaly areas. These are the cleanest background waters in the country.

At the other end, the areas where the nearest waterbody is rated “Poor” cluster in the western midlands (R32 Portlaoise, R51 Kildare town, R35 Tullamore), parts of west Dublin (D10, D15, D22, D24, K78 Lucan), Cork city (T12), and H14 (Monaghan). Some of that is agricultural catchment pressure; some is urban stormwater. Either way it's a signal — the river at the end of the road is not pristine.

The cleanest composite profiles: coastal south and north Dublin

Once we combine all three signals, the top of the ranking is dominated by two clusters:

Dublin coast, north and south

K32 Balbriggan/Stamullen (score 95, 0% flood, Good water within 1.3 km, Front Strand Beach within 900 m), D18 Foxrock/Cabinteely (87 — Seapoint Blue Flag at 4.5 km), K45 Lusk (87 — Portrane Beach at 5.1 km), A98 Bray (87 — Bray South Promenade at 3.1 km), D13 Sutton/Baldoyle (85 — Burrow Beach at 1.9 km), and D04 Ballsbridge/Sandymount (85 — Sandymount Strand at 1.6 km) all score highly. This isn't surprising: these are areas where people historically chose to live because of proximity to the coast, and the environmental data backs up the reputation.

Cork coast and West Cork

P17 Kinsale (95, tied first), P24 Midleton / East Cork, P43 Carrigaline and the Cork south suburbs, P85 Skibbereen / Clonakilty, and F23 west Cork / south Kerryall score in the high 80s. The P85 and F23 areas specifically pair zero flood exposure with High-status (not just Good) water quality — an exceptional combination in the Irish context.

For landlocked buyers

The score penalises anywhere more than 25 km from a Blue Flag beach, which is a deliberate bias toward coastal amenity. For inland buyers the more useful question is: which inland Eircode areas combine zero flood exposure with Good or better water quality? The answers:

• F12 Athlone / south Roscommon — Good water at 4.3 km
• F45 east Galway / Roscommon — Good water at 0.9 km
• H53 Carrick-on-Shannon — Good water at 1.2 km
• P12 Mallow / north Cork — Good water at 2.2 km
• P56 Fermoy / north Cork — Good water at 0.8 km
• P61 Macroom hinterland — Good water at 2.6 km
• C15 Maynooth / Leixlip (though only Moderate water)

Outside those, inland Ireland tends to cluster at Moderate water status — the background picture of agricultural pressure on midland rivers.

What this means if you're buying

• Buying in Dublin 2 or Ashbourne? Pull the OPW flood map for the specific address before you bid. Area-wide 95%+ exposure doesn't mean the specific property will flood, but it raises the probability meaningfully. Ask the seller for their flood-insurance history — if they've had a claim, it'll affect your premium.
• Buying in a river town? The town name is a tell. Macroom, Clonmel, Ennis, Wexford, Waterford, Gorey — each has a meaningful fraction of its housing stock in a flood zone. Treat flood-map-checking as a default, not an optional extra.
• Chasing water quality? Anywhere west of Bantry or south of Skibbereen is effectively the premium tier for Irish background water quality. The trade-off is the commute to anywhere else.
• Weighing coastal vs inland? Our score favours the coast, but that's a preference, not a fact. If you don't care about beaches, use the flood + water quality components alone — many inland areas score perfectly on those.

How we did this

Data sources: Property Price Register (sale locations, last 24 months, excluding sales flagged as not full market price); OPW CFRAM flood zones (79,713 fluvial and coastal polygons, 100-year return period, current scenario); EPA Water Framework Directive water quality monitoring (4,840 waterbodies with status ratings); Blue Flag / Green Coast beach registry (245 accredited beaches via the EPA bathing water dataset). Area centroids are computed as the median lat/lon of sales in each routing key — robust to geocoder outliers. For each area we computed the percentage of recent sales that intersect any flood polygon, the status of the nearest water-quality monitoring station, and the straight-line distance to the nearest Blue Flag beach. Composite score formula: flood (50 pts) + water quality (30 pts) + beach proximity (20 pts) — published above. 126 routing keys had at least 100 recent sales and were included in the ranking. This analysis deliberately does not include radon — our current radon polygon coverage contains only Low-risk polygons, so the EPA high-risk areas aren't represented. We'll revisit once the full EPA radon grid is loaded.