Colwyn Bay Water Hardness & Quality Report (2026)
Water Hardness
5.2°Clark7.4°fH4.1°dH
Source
reservoir
pH Level
7.4
neutral = 7.0
Lead
0.002 mg/L
✓ Below action level
TDS
130.9 mg/L
Est. Daily Cost
£0.17
energy & soap waste
Source: DWI Data Portal · Updated 2026
0–60
mg/L
Soft
61–120
mg/L
Moderately Hard
121–180
mg/L
Hard
180+
mg/L
Very Hard
Appliance Damage Report
In Colwyn Bay, your appliances are currently losing 10% efficiency due to mineral buildup.
| Appliance | In Colwyn Bay | Soft Water City | Efficiency Loss |
|---|---|---|---|
| Kettle | 7.2 yrs | 8.5 yrs | -15% |
| Washing Machine | 10.9 yrs | 12 yrs | -9% |
| Water Heater | 12.7 yrs | 15 yrs | -15% |
Regional Water Comparison
How Colwyn Bay compares to its nearest neighbours
| City | Hardness | Clark° | Risk | Source |
|---|---|---|---|---|
| ▶ Colwyn Bay, Wales | 73.5 mg/L | 5.2° | 🟡 Moderately Hard | reservoir |
| Llandudno, Wales | 136.5 mg/L | 9.6° | 🟠 Hard | reservoir |
| Abergele, Wales | 78 mg/L | 5.5° | 🟡 Moderately Hard | reservoir |
| Rhyl, Wales | 66.5 mg/L | 4.7° | 🟡 Moderately Hard | reservoir |
| Prestatyn, Wales | 84 mg/L | 5.9° | 🟡 Moderately Hard | reservoir |
National Benchmark
How Colwyn Bay compares to the United Kingdom average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ Colwyn Bay | 73.5 mg/L | 🟡 Low |
| United Kingdom National Avg | 183 mg/L | 🔴 High |
| Livingston Top Rated | 8.5 mg/L | 🟢 None |
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What Makes Colwyn Bay's Water Unique?
Local geology and source profile
Colwyn Bay, the north Wales coastal resort in Conwy County Borough, is served by Dŵr Cymru Welsh Water. Supply draws on the Llyn Cowlyd Reservoir — one of the deepest natural lakes in Wales, set in the Carneddau range above the Conwy valley — and the broader upper Conwy catchment, which drains some of the highest and most ancient mountains in Wales. Rainfall collected from these high-altitude catchments is treated at Dolgarrog Water Treatment Works in the Conwy valley before distribution along the north Wales coast to Colwyn Bay, Llandudno Junction and Abergele. The ultra-low TDS of 130.9 mg/L confirms a pure mountain water character with minimal dissolved minerals — one of the lowest TDS values in the north Wales coastal supply zone.
The Carneddau and upper Conwy catchment drains predominantly over Ordovician volcanic rocks (rhyolite, andesite and tuff of the Snowdonian Volcanic Series) and Cambrian and Ordovician slates and mudstones — ancient metamorphic and igneous rocks that are exceptionally inert with respect to calcium carbonate dissolution. Rainfall on these uplands produces inherently soft, slightly acidic water with negligible mineral content. The very low TDS of 130.9 mg/L and hardness of 73.5 mg/L reflect the almost pure rainfall-character of Llyn Cowlyd supply, with only trivial mineral acquisition during treatment and distribution.
At 73.5 mg/L Colwyn Bay has very soft water, making household appliance maintenance easy and laundry efficiency high. Kettles need descaling only every two to three months — a brief soak in diluted white vinegar removes any faint scale film. Shower screens remain clear for weeks without cleaning. Washing-up liquid lathers generously with a small amount. Combi-boilers and white goods appliances face very low limescale risk, extending their effective lifespans significantly compared with hard-water areas in England. One practical note: the natural softness of Welsh mountain water means it can be slightly corrosive to older lead pipework — properties in Victorian Colwyn Bay housing should check tap water quality if they suspect old lead pipes remain in the service connection.
Geology & Source: Supplied by Dŵr Cymru Welsh Water from Llyn Cowlyd Reservoir and the Conwy valley catchment — Ordovician and Silurian volcanic and slate terrain, Snowdonia fringe — produces very soft water at 73.5 mg/L (5.2°Clark).