South Downs Water
Natural mineral water from a 420 ft artesian well at Windsor House, Southbourne, near Emsworth, on the Hampshire and West Sussex border. Defra’s register lists it as “South Down Natural Mineral Water”, source “Windsor House Spring”. The producer and Companies House share that address, so this is the registered source. The producer says the well was opened in 1918 for the Ministry of Defence and the Windsor family began bottling on 7 April 1990. Will Windsor has owned and run it since 2013. Southdowns Water Co Ltd, incorporated May 2013, is controlled by William Thomas Gregory Windsor (Companies House, 75% or more since April 2016). Goodwood’s own release dates its water partnership to 2018.
Mineral composition
| mg/L | |
|---|---|
| Calcium | 91 |
| Magnesium | 2 |
| Sodium | 9 |
| Sulfate | 5 |
| Chloride | 17 |
| Bicarbonate | 214 |
Compositions can vary by season and source. Read our methodology.
Mineral character
A chalk water: hard, calcium-bicarbonate, with almost no magnesium and little sulphate. Per litre: calcium 91.0 mg, magnesium 2.3 mg, sodium 8.7 mg, bicarbonate 214.0 mg, sulphate 4.5 mg, chloride 17 mg, nitrate 12.5 mg. Hardness is about 237 mg/L as CaCO₃, pH 7.5. Calcium outweighs magnesium about 40 to 1; only Hildon (about 48 to 1) is higher in our database. The analysis is undated and covers the whole range. The published ions don’t fully balance: anions, counting nitrate, are about 16% below cations. That may be rounding or an unlisted ion.
Use-case suitability
- CoffeeNot used in any current coffee recipe, but hardness 237 mg/L sits within the 9–266 mg/L range typical for these targets.
- TeaNot used in any current tea recipe. Hardness 237 mg/L is above the 37–59 mg/L range of these targets.
- BrewingNot used in any current brewing recipe, but hardness 237 mg/L sits within the 26–922 mg/L range typical for these targets.
- BakingNot used in any current baking recipe, but hardness 237 mg/L sits within the 46–390 mg/L range typical for these targets.
- AquariumNot used in any current aquarium recipe. Hardness 237 mg/L is above the 35–212 mg/L range of these targets.
- HorticultureNot used in any current horticulture recipe. Hardness 237 mg/L is above the 12–54 mg/L range of these targets.
Where to buy
UK
Producer webshop (England and Wales), Producer delivery round (Sussex, Hampshire, Surrey, London), Regional drinks distributors, On-trade (Goodwood Estate and others)
£13.78 per 12 x 1.5 L; £14.58 per 24 x 500 ml (producer webshop, 2026-10-14) per litre
Sold on the producer’s webshop (England and Wales), its own delivery round across Sussex, Hampshire, Surrey and London, regional distributors and the on-trade. Webshop prices on 14 October 2026: 12 × 1.5 L still £13.78, 24 × 500 ml still £14.58, 24 × 500 ml sparkling £15.34, 24 × 330 ml still £14.24. Also glass, cans and cooler bottles. The stockists page (last changed January 2024) shows logos including The Southern Co-operative and Majestic; we haven’t checked those listings.