Charlton Water Hardness & Quality Report (2026)

Thames Water supplies Charlton in the Royal Borough of Greenwich in south-east London near Woolwich, via the Thames Water south London ring main drawing from Bough Beech Reservoir in the Eden Valley of west Kent. At 314 mg/L (22.0°Clark) and a TDS of 903.7 mg/L, Charlton's water is extremely hard — among the most mineralised supplies anywhere in Greater London — placing it firmly in the cluster of south-east London zones with TDS values approaching or exceeding 900 mg/L, alongside Forest Hill (327 mg/L, TDS 967.3), Ladywell (316.5 mg/L, TDS 917), and Crofton Park (316 mg/L, TDS 915.6).

The south-east London supply corridor in Thames Water's distribution network — spanning the boroughs of Lewisham and Greenwich from Catford to Woolwich — is characterised by an extraordinary cluster of extremely hard supply zones with TDS values far exceeding the 600–700 mg/L range typical of other Thames Water London zones. The Bough Beech chalk supply from the North Downs is routed through specific distribution infrastructure in south-east London that delivers a very concentrated chalk mineral fraction to the Charlton, Greenwich, and Lewisham supply zone — an unusual geographical concentration of extreme hard water within London.

At 314 mg/L, limescale is a severe and persistent household problem in Charlton. Kettles must be descaled weekly to prevent rapid element failure. The combi-boiler faces very high risk of premature breakdown without a properly fitted, annually replaced scale inhibitor and regular professional servicing. Washing-up liquid barely lathers without generous quantities of product. Taps, shower heads, and all basin fittings develop heavy chalk encrustation within days; at minimum a weekly descaling with white vinegar or a proprietary product is essential. A whole-house water softener is very strongly recommended for all Charlton households.