Water Hardness and Quality in Sevenoaks
Supplied by Thames Water · Swanley (SLE38)
Sevenoaks has very hard water with quality that meets all UK drinking water standards.
Check a specific postcode in Sevenoaks
Water Quality Scorecard
Total Hardness
Guideline: 150+ mg/l is considered hard
327mg/l CaCO₃
UK Average: 197.72 mg/l CaCO₃Well Above Average
LowAverageHigh
pH Level
UK Standard: 6.5 – 9.5
7.2pH units
UK Average: 7.43 pH unitsWell Below Average
LowAverageHigh
Free Chlorine
Guideline: below 1 mg/l
0.45mg/l
UK Average: 0.45 mg/lAverage
LowAverageHigh
Nitrate
UK Standard: max 50 mg/l
37mg/l
UK Average: 16.9 mg/lWell Above Average
LowAverageHigh
Lead
UK Standard: max 10 µg/l
0.9µg/l
UK Average: 1.08 µg/lAbove Average
LowAverageHigh
Fluoride
UK Standard: max 1.5 mg/l
0.11mg/l
UK Average: 0.19 mg/lAverage
LowAverageHigh
Water Hardness in Sevenoaks
Hardness is the most searched water quality metric. It affects limescale buildup in kettles, boilers, and pipes.
327mg/l CaCO₃Very Hard
Soft
Mod. Soft
Slightly Hard
Mod. Hard
Hard
Very Hard
Sevenoaks has hard water at 327 mg/l. You will likely experience significant limescale buildup in kettles, boilers, and on bathroom surfaces. Many residents in your area use water softeners or anti-limescale products.
Water Source Information
- Water Company
- Thames Water
- Supply Zone
- Swanley (SLE38)
- Source Type
- River
- Treatment Works
- Swanley Treatment Works
- Last Tested
- 2025-12-31
- Data Source
- Thames Water
Frequently Asked Questions
Is the water hard in Sevenoaks?▾
Yes, Sevenoaks has hard water at 327 mg/l CaCO₃. This is classified as "Very Hard" on the standard scale. You may notice limescale buildup in kettles and on taps.
Is Sevenoaks tap water safe to drink?▾
Yes, tap water in Sevenoaks is safe to drink. It is treated and tested by Thames Water and meets all UK Drinking Water Inspectorate standards. All tested parameters are within regulatory limits.
What is the water hardness in Sevenoaks?▾
The water hardness in Sevenoaks is 327 mg/l CaCO₃, which is classified as "Very Hard". This is above the UK national average of 170 mg/l.
Who supplies water to Sevenoaks?▾
Water in Sevenoaks is supplied by Thames Water, which serves the London and Thames Valley region. The water comes from river sources and is treated at Swanley Treatment Works.