UK Water Quality Report • 2026 Data

Water Hardness in SL5

Water supply analysis across 5 postcode sectors in SL5 (Affinity Water).

Outcode Avg Hardness290 PPMHard Water
Regional Quality Overview

Water Supply Analysis: Outcode SL5

Looking for water hardness metrics in SL5? Water supplied by Affinity Water in this outcode registers a baseline average of 290 PPM across 5 distinct postcode sectors.

Water chemistry can fluctuate across supply zones in SL5. The lowest mineral concentration is recorded in sector SL5 0 at 290 PPM, whereas sector SL5 9 experiences higher mineral levels reaching 290 PPM.

Due to the hard water (290 PPM) in SL5, 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 SL5

Lowest mineral concentration

Softest
Sector SL5 0187 Postcodes • Hard
290 PPM20.3 °Clark

Hardest Sector in SL5

Highest mineral concentration

Highest Hardness
Sector SL5 9241 Postcodes • Hard
290 PPM20.3 °Clark

All Postcode Sectors in SL5

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