New Milton Water Hardness & Quality Report (2026)

New Milton, the Hampshire coastal town in the New Forest district between Christchurch and Lymington, is supplied by Southern Water from deep confined Chalk Aquifer boreholes beneath the Hampshire coastal plain. Despite the town itself sitting on Eocene Barton Clay and Barton Beds (Tertiary marine clay and sand deposits) at the surface — the geological formation that underlies much of the New Forest lowland fringe — the domestic water supply is drawn from chalk boreholes that penetrate through the Tertiary cover to the Cretaceous Chalk below. This deep confined chalk, isolated from recent surface recharge by the thick Tertiary clay overburden, carries groundwater with very long residence times that dissolves calcium bicarbonate to near-saturation. The extraordinary TDS of 890.9 mg/L at 297 mg/L hardness confirms deep confined chalk borehole water, chemically similar to the Christchurch supply zone (289 mg/L, TDS 888.3) a few miles to the west along the same Hampshire coastal chalk borehole belt.

The Cretaceous Chalk beneath the Hampshire coastal plain dips south under the Solent, with the confined zone beginning inland under the Barton and Headon Beds of the New Forest fringe. Groundwater in the confined chalk acquires extreme calcium bicarbonate concentrations over decades of underground residence, supplemented by sulphate from the Eocene sand and clay deposits above the chalk that contribute to the elevated TDS. The consistent similarity in hardness and TDS between New Milton, Christchurch and the New Forest chalk supply zone confirms a single deep confined chalk aquifer system feeding the entire Hampshire coastal belt south of the New Forest.

At 297 mg/L New Milton's water is very hard and limescale is a severe domestic problem. Kettle elements fur within days of descaling and require fortnightly treatment with concentrated citric acid. Shower screens develop a dense opaque calcium crust within a week without daily wiping. Washing-up liquid must be used generously. Combi-boilers face a serious risk of scale-related failure without inline magnetic scale inhibitors and annual engineer servicing. A whole-house water softener is strongly recommended for New Milton homeowners. The town's pleasant New Forest coastal character contrasts sharply with the extreme chalk hardness of its daily tap water.