Swanage Water Hardness & Quality Report (2026)
Water Hardness
20.2°Clark28.8°fH16.1°dH
Source
mixed
pH Level
8.5
neutral = 7.0
Lead
0.006 mg/L
✓ Below action level
TDS
863.6 mg/L
Est. Daily Cost
£0.65
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 Swanage, your appliances are currently losing 38% efficiency due to mineral buildup.
| Appliance | In Swanage | Soft Water City | Efficiency Loss |
|---|---|---|---|
| Kettle | 1.5 yrs | 8.5 yrs | -82% |
| Washing Machine | 3 yrs | 12 yrs | -75% |
| Water Heater | 5 yrs | 15 yrs | -67% |
Regional Water Comparison
How Swanage compares to its nearest neighbours
| City | Hardness | Clark° | Risk | Source |
|---|---|---|---|---|
| ▶ Swanage, South West | 288 mg/L | 20.2° | 🔴 Very Hard | mixed |
| Poole, South West | 204 mg/L | 14.3° | 🔴 Very Hard | mixed |
| Bournemouth, South West | 90 mg/L | 6.3° | 🟡 Moderately Hard | groundwater |
| Canford Heath, South West | 153 mg/L | 10.7° | 🟠 Hard | mixed |
| Broadstone, South West | 151.5 mg/L | 10.6° | 🟠 Hard | mixed |
National Benchmark
How Swanage compares to the United Kingdom average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ Swanage | 288 mg/L | 🔴 High |
| United Kingdom National Avg | 183 mg/L | 🔴 High |
| Livingston Top Rated | 8.5 mg/L | 🟢 None |
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What Makes Swanage's Water Unique?
Local geology and source profile
Bournemouth Water (now part of South West Water) supplies Swanage, the Isle of Purbeck coastal resort town in Dorset — a beloved Victorian seaside town at the southern end of Studland Bay, ringed by the chalk downland of Ballard Down, the Jurassic Coast UNESCO World Heritage Site coastline of Purbeck limestone, and the working Swanage Railway steam heritage line through the Purbeck Hills — from the Purbeck Chalk (Cretaceous) and Purbeck Limestone (Jurassic) aquifer system in the Isle of Purbeck supply zone, treated at Alton Road Water Treatment Works in Bournemouth. At 288 mg/L (20.2°Clark) and a TDS of 863.6 mg/L, Swanage's water is extremely hard with a remarkably elevated TDS/hardness ratio (3.0) — indicating very high sulphate content from the Purbeck Evaporites (gypsum beds within the Purbeck Formation) and the dissolution of Purbeck Marble (a freshwater limestone) in the Swanage aquifer system.
Swanage sits within the Isle of Purbeck geological structure — an anticlinal ridge of Cretaceous Chalk and Jurassic Purbeck Limestone enclosing the Purbeck basin. The Purbeck Formation contains abundant gypsum (calcium sulphate) beds in the upper Jurassic sequence — the same Purbeck Gypsum that has been quarried at Lockhaugh and other local sites — contributing significant sulphate to groundwater. Combined with chalk calcium carbonate, this produces 288 mg/L with TDS 863.6 mg/L — extremely hard, sulphate-enriched water with the highest TDS/hardness ratio in the dataset at 3.0.
At 288 mg/L, limescale is a severe and relentless household problem in Swanage. Kettles should be descaled every week to ten days. The combi-boiler requires a fitted scale inhibitor and annual professional servicing as an absolute minimum. Washing-up liquid requires very generous quantities. Taps and shower heads develop heavy chalk deposits within days; frequent descaling with white vinegar or a proprietary product is essential. A whole-house water softener is strongly recommended — the Purbeck Gypsum-enriched chalk supply at Swanage is one of the most mineralised in England, a geological feature as dramatic in the domestic sphere as the Jurassic limestone cliff stacks at Handfast Point are to visitors on the coastal path.
Geology & Source: Supplied by Bournemouth Water (now South West Water) from the Purbeck Chalk and Purbeck Limestone aquifer system in the Isle of Purbeck supply zone — treated at Alton Road Water Treatment Works — produces extremely hard water at 288 mg/L (20.2°Clark).