Executive Summary: Sector SY4 9 vs Sector SW1A 1
Comparing tap water mineral concentration between Sector SY4 9 (Severn Trent Water) and Sector SW1A 1 (Thames Water) reveals a water hardness difference of 115 PPM. Sector SY4 9 has softer water at 160 PPM (Moderately Hard) compared to Sector SW1A 1 at 275 PPM (Hard).
Limescale risk and boiler heating efficiency vary based on these mineral levels. Households in Sector SW1A 1 experience higher heating element degradation and kettle scale accumulation due to elevated calcium carbonate density (275 PPM vs 160 PPM).
For home appliance setup, Bosch dishwasher water softener settings should be calibrated accordingly: Sector SY4 9 requires setting H02 whereas Sector SW1A 1 recommends setting H04.