Musselburgh Water Hardness & Quality Report (2026)

Musselburgh, the historic East Lothian town on the Firth of Forth at the mouth of the River Esk east of Edinburgh — the oldest municipality in Scotland and home of golf — is supplied by Scottish Water from the Pentland Hills reservoir system. The primary sources are Glencorse, Loganlea and Threipmuir Reservoirs in the Pentland Hills south-west of Edinburgh, fed by drainage from the Silurian and Ordovician greywacke, mudstone and greywacke grit moorland of the Pentland Hills. The Pentland Hills form a compact range of 500–600 m hills draining west-facing moorland — classic upland terrain that generates very soft, peaty, low-mineral runoff. Scottish Water treats the supply at Glencorse Water Treatment Works before distribution through the Edinburgh and East Lothian network. At 18.5 mg/L with TDS 31.5 mg/L, Musselburgh's water is among the softest in Scotland and in the whole of the UK — essentially mountain-rainfall quality, as mineral-poor as high alpine spring water.

The Silurian and Ordovician greywacke and mudstone of the Pentland Hills are ancient compressed marine sedimentary rocks entirely lacking in calcium carbonate. These calcium-poor formations generate rapid, slightly peaty moorland runoff with virtually no mineral content. The Glencorse and Loganlea catchments above 300 m on the Pentland watershed drain these impermeable, silicic formations, accumulating precipitation of near-distilled quality into the reservoirs. At TDS 31.5 mg/L the Musselburgh supply is slightly harder than Arbroath (TDS 19.7) but barely mineralised by any normal standard — a characteristically ultra-soft Edinburgh/Lothian supply.

At 18.5 mg/L Musselburgh's water is exceptionally soft — essentially limescale-free in every household context. Kettles can run for months without descaling. Shower screens remain crystal clear. Washing-up liquid froths with a single drop. Combi-boilers and appliances have effectively zero scaling risk. Musselburgh's position on the North Sea coast at the edge of Edinburgh's urban fringe means every household benefits from the extraordinary Pentland Hills water quality — far removed from the hard chalk experience of East Anglian or South East English towns of similar size.