Teignmouth Water Hardness & Quality Report (2026)

South West Water supplies Teignmouth, a seaside and port town at the mouth of the River Teign in south Devon, from Tottiford Reservoir and Trenchford Reservoir on the granite fringe of Dartmoor above Bovey Tracey, blended with contributions from Devonian limestone and Permian Breccia sources in the lower Teign Valley and south Devon distribution zone, treated at regional south Devon works. At 238 mg/L (16.7°Clark), Teignmouth's water is hard — considerably harder than the soft granite Dartmoor source baseline — reflecting the significant influence of Devonian limestone and Carboniferous limestone geology in the south Devon supply zone between Dartmoor and Torbay.

The Tottiford and Trenchford reservoirs drain the eastern fringe of Dartmoor, at the transition from granite moorland to the Devonian sedimentary geology of south Devon. West of Teignmouth, the Devonian limestone reef complexes of the Torbay and Newton Abbot area — the same Devonian marble limestone that creates Berry Pomeroy and the Torquay limestone caves — contribute hard groundwater to the south Devon distribution blend. This Devonian limestone water significantly elevates the hardness at Teignmouth above the Dartmoor granite reservoir baseline to 238 mg/L with TDS 690.6 mg/L.

At 238 mg/L, limescale is a persistent household challenge in Teignmouth. Kettles should be descaled monthly to maintain element efficiency. The combi-boiler benefits from a fitted scale inhibitor and annual professional servicing. Washing-up liquid requires more product than in softer areas to achieve satisfactory lather. Taps and shower heads develop visible white limescale within one to two weeks; a fortnightly wipe with white vinegar or a proprietary descaling product keeps fittings clean in this hard south Devon Devonian limestone-influenced supply zone.