UK Water Quality Report • 2026 Data

Water Hardness in KT18

Water supply analysis across 3 postcode sectors in KT18 (Thames Water).

Outcode Avg Hardness270 PPMHard Water
Regional Quality Overview

Water Supply Analysis: Outcode KT18

Analyzing water quality disclosures across all 3 postcode sectors in outcode KT18 reveals an average water hardness of 270 PPM (Hard Water). Public water supply across this area is managed by Thames Water, responsible for treating and delivering water to residential households.

Water chemistry can fluctuate across supply zones in KT18. The lowest mineral concentration is recorded in sector KT18 6 at 260 PPM, whereas sector KT18 7 experiences higher mineral levels reaching 275 PPM.

Due to the hard water (270 PPM) in KT18, limescale build-up can occur on heating elements, shower heads, and boilers. Setting your dishwasher water softener to the correct level (e.g. Bosch setting H04) is strongly recommended to prevent cloudy glassware and internal scale accumulation. Review the individual postcode sectors below to get precise dishwasher salt settings and limescale recommendations.

Softest Sector in KT18

Lowest mineral concentration

Softest
Sector KT18 699 Postcodes • Hard
260 PPM18.2 °Clark

Hardest Sector in KT18

Highest mineral concentration

Highest Hardness
Sector KT18 7188 Postcodes • Hard
275 PPM19.3 °Clark

All Postcode Sectors in KT18

Select a postcode sector below to view exact water softener salt settings, limescale protection guides, and appliance recommendations.