Garston Water Hardness & Quality Report (2026)

Garston, the south Liverpool district between Speke, Allerton and the Mersey docks at the southern end of Liverpool city — formerly the site of the Garston Docks gas works and South Liverpool's Victorian dockland — is supplied by United Utilities from the Thirlmere Aqueduct (Lake District) blended with significant local groundwater from the Permo-Triassic Sherwood Sandstone beneath the south Liverpool plain. At 161 mg/L with TDS 456.8 mg/L (ratio 2.84), Garston's supply is dramatically harder than the adjacent Speke zone (93 mg/L, TDS 227.4 mg/L) just over a mile south-east — a supply sub-zone boundary that separates the Thirlmere-dominant Speke zone from the Triassic-sandstone-dominant Garston supply branch. The elevated TDS-to-hardness ratio (2.84) confirms a significant calcium sulphate contribution from Keuper Marl evaporite interbeds in the Triassic sub-surface beneath south Liverpool, the same evaporite mineral signature that characterises the Newton-le-Willows (192 mg/L) and Swinton (197.5 mg/L) supply zones elsewhere in the United Utilities west Lancashire–Greater Manchester network.

The Permo-Triassic Sherwood Sandstone beneath south Liverpool is a productive aquifer carrying moderately hard, sulphate-enriched groundwater from the sandstone cement and Keuper Marl gypsum beds at 50–120 m depth beneath the Mersey lowland. United Utilities distributes both the Thirlmere soft-aqueduct supply and the local Triassic groundwater through the south Liverpool network, with the Garston supply sub-zone drawing a notably higher proportion of the harder, more mineralised Triassic groundwater compared with the Thirlmere-dominant Speke zone.

At 161 mg/L Garston's water is moderately hard and limescale management is a regular domestic task. Kettles benefit from descaling every four to five weeks with a citric acid tablet. Shower screens develop steady calcium spotting requiring regular white vinegar treatment. Washing-up liquid must be used in moderate amounts. Combi-boilers benefit from inline scale inhibitor protection. Garston's south Liverpool dockland-heritage character — the Victorian Garston Docks, the South Liverpool railway and the Mersey river front — is combined with the harder Triassic sandstone water supply that flows from every household tap in this south Liverpool supply sub-zone.