UK Water Quality Report • 2026 Data

Water Hardness in TW12

Water supply analysis across 4 postcode sectors in TW12 (Thames Water).

Outcode Avg Hardness275 PPMHard Water
Regional Quality Overview

Water Supply Analysis: Outcode TW12

Analyzing water quality disclosures across all 4 postcode sectors in outcode TW12 reveals an average water hardness of 275 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 TW12. The lowest mineral concentration is recorded in sector TW12 1 at 275 PPM, whereas sector TW12 9 experiences higher mineral levels reaching 275 PPM.

Due to the hard water (275 PPM) in TW12, 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 TW12

Lowest mineral concentration

Softest
Sector TW12 1163 Postcodes • Hard
275 PPM19.3 °Clark

Hardest Sector in TW12

Highest mineral concentration

Highest Hardness
Sector TW12 920 Postcodes • Hard
275 PPM19.3 °Clark

All Postcode Sectors in TW12

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