Water Hardness and Quality in Guildford
Supplied by Thames Water · Guildford North & SW (G1)
Guildford has hard water with quality that meets all UK drinking water standards.
Check a specific postcode in Guildford
Water Quality Scorecard
Total Hardness
Guideline: 150+ mg/l is considered hard
206mg/l CaCO₃
UK Average: 197.72 mg/l CaCO₃Average
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
0.48mg/l
UK Average: 0.45 mg/lAverage
LowAverageHigh
Nitrate
UK Standard: max 50 mg/l
21mg/l
UK Average: 16.9 mg/lAbove 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
0.13mg/l
UK Average: 0.19 mg/lAbove Average
LowAverageHigh
Water Hardness in Guildford
Hardness is the most searched water quality metric. It affects limescale buildup in kettles, boilers, and pipes.
206mg/l CaCO₃Hard
Soft
Mod. Soft
Slightly Hard
Mod. Hard
Hard
Very Hard
Guildford has hard water at 206 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
- Guildford North & SW (G1)
- Source Type
- Groundwater
- Treatment Works
- Guildford North & SW Treatment Works
- Last Tested
- 2025-12-31
- Data Source
- Thames Water
Frequently Asked Questions
Is the water hard in Guildford?▾
Yes, Guildford has hard water at 206 mg/l CaCO₃. This is classified as "Hard" on the standard scale. You may notice limescale buildup in kettles and on taps.
Is Guildford tap water safe to drink?▾
Yes, tap water in Guildford 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 Guildford?▾
The water hardness in Guildford is 206 mg/l CaCO₃, which is classified as "Hard". This is above the UK national average of 170 mg/l.
Who supplies water to Guildford?▾
Water in Guildford is supplied by Thames Water, which serves the London and Thames Valley region. The water comes from underground aquifers and is treated at Guildford North & SW Treatment Works.