UK Water Quality Report • 2026 Data

Water Hardness in SL3

Water supply analysis across 6 postcode sectors in SL3 (Thames Water).

Outcode Avg Hardness275 PPMHard Water
Regional Quality Overview

Water Supply Analysis: Outcode SL3

Analyzing water quality disclosures across all 6 postcode sectors in outcode SL3 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 SL3. The lowest mineral concentration is recorded in sector SL3 0 at 275 PPM, whereas sector SL3 9 experiences higher mineral levels reaching 275 PPM.

Due to the hard water (275 PPM) in SL3, 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 SL3

Lowest mineral concentration

Softest
Sector SL3 0162 Postcodes • Hard
275 PPM19.3 °Clark

Hardest Sector in SL3

Highest mineral concentration

Highest Hardness
Sector SL3 9171 Postcodes • Hard
275 PPM19.3 °Clark

All Postcode Sectors in SL3

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