Water Hardness and Quality in Marlborough
Supplied by Thames Water · Marlborough (S9)
Marlborough has very hard water with quality that meets all UK drinking water standards.
Check a specific postcode in Marlborough
Water Quality Scorecard
Total Hardness
Guideline: 150+ mg/l is considered hard
302mg/l CaCO₃
UK Average: 197.72 mg/l CaCO₃Well Above Average
LowAverageHigh
pH Level
UK Standard: 6.5 – 9.5
7.3pH units
UK Average: 7.43 pH unitsBelow Average
LowAverageHigh
Free Chlorine
Guideline: below 1 mg/l
0.59mg/l
UK Average: 0.45 mg/lWell Above Average
LowAverageHigh
Nitrate
UK Standard: max 50 mg/l
41mg/l
UK Average: 16.9 mg/lWell Above Average
LowAverageHigh
Lead
UK Standard: max 10 µg/l
1.2µg/l
UK Average: 1.08 µg/lWell Above Average
LowAverageHigh
Fluoride
UK Standard: max 1.5 mg/l
0.07mg/l
UK Average: 0.19 mg/lWell Below Average
LowAverageHigh
Water Hardness in Marlborough
Hardness is the most searched water quality metric. It affects limescale buildup in kettles, boilers, and pipes.
302mg/l CaCO₃Very Hard
Soft
Mod. Soft
Slightly Hard
Mod. Hard
Hard
Very Hard
Marlborough has hard water at 302 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
- Marlborough (S9)
- Source Type
- Groundwater
- Treatment Works
- Marlborough Treatment Works
- Last Tested
- 2025-12-31
- Data Source
- Thames Water
Frequently Asked Questions
Is the water hard in Marlborough?▾
Yes, Marlborough has hard water at 302 mg/l CaCO₃. This is classified as "Very Hard" on the standard scale. You may notice limescale buildup in kettles and on taps.
Is Marlborough tap water safe to drink?▾
Yes, tap water in Marlborough 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 Marlborough?▾
The water hardness in Marlborough is 302 mg/l CaCO₃, which is classified as "Very Hard". This is above the UK national average of 170 mg/l.
Who supplies water to Marlborough?▾
Water in Marlborough is supplied by Thames Water, which serves the London and Thames Valley region. The water comes from underground aquifers and is treated at Marlborough Treatment Works.