UK Water Quality Report • 2026 Data

Water Hardness in TW18

Water supply analysis across 5 postcode sectors in TW18 (Affinity Water).

Outcode Avg Hardness290 PPMHard Water
Regional Quality Overview

Water Supply Analysis: Outcode TW18

Analyzing water quality disclosures across all 5 postcode sectors in outcode TW18 reveals an average water hardness of 290 PPM (Hard Water). Public water supply across this area is managed by Affinity Water, responsible for treating and delivering water to residential households.

Water chemistry can fluctuate across supply zones in TW18. The lowest mineral concentration is recorded in sector TW18 1 at 290 PPM, whereas sector TW18 9 experiences higher mineral levels reaching 290 PPM.

Due to the hard water (290 PPM) in TW18, 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 TW18

Lowest mineral concentration

Softest
Sector TW18 1203 Postcodes • Hard
290 PPM20.3 °Clark

Hardest Sector in TW18

Highest mineral concentration

Highest Hardness
Sector TW18 929 Postcodes • Hard
290 PPM20.3 °Clark

All Postcode Sectors in TW18

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