Affinity Water Water Hardness
The UK's largest water-only supply company delivering 950 million litres daily to 3.8 million customers. Discover network-wide PPM ratings, chalk aquifer vs reservoir water sources, and local appliance calibration guidelines.
Is Affinity Water Water Hard or Soft?
Yes, Affinity Water delivers some of the hardest tap water in Great Britain, averaging 290 to 325 PPM (20.3° to 22.8° Clark). Over 65% of supply is drawn directly from deep chalk aquifers beneath Hertfordshire, Buckinghamshire, and Surrey.
Primary Abstraction: Water is abstracted from deep boreholes in the Chiltern Hills and North Downs chalk beds, with additional surface water blended from the River Thames and lowland Essex rivers.
Where Does Affinity Water Water Come From?
Water hardness across Affinity Water's licensed territory is strictly determined by regional hydrogeology. Rainwater is naturally soft when it falls from clouds, but absorbs dissolved minerals as it percolates through soil and rock layers before municipal abstraction.
Major population centers served by Affinity Water include: Woking, St Albans, Watford, Luton, Hemel Hempstead, Stevenage, Harlow. If your water bill comes from Affinity Water, your tap water is certified by the Drinking Water Inspectorate (DWI) and adheres to all British potable safety standards.
DWI Technical Reference
- Supplier Codeaffinity-water
- Typical Range280 – 340 PPM (mg/L CaCO3)
- Source Classificationchalk groundwater
- Coverage RegionCentral (Herts, Bucks, N London), Southeast (Surrey), and Eastern (Essex)
Appliance Care & Heating Compliance for Affinity Water Customers
Descale every 2–3 weeks with citric acid crystals. Never let calcium crust bake permanently onto heating bases.
Calibrate to H05 or H06 on Bosch/Neff, or Level 4 on Beko. Do not run appliances without salt.
Mandatory scale reduction on boiler cold feeds under Building Regulations Part L (>200 PPM).
Affinity Water Network Postcode Outcodes (146)
Search and explore official DWI water hardness readings across all postal districts supplied by Affinity Water.
Living in a Hard Water Zone (WD99 averages 290 PPM)? Compare Approved Local Installers
Get up to 3 free, no-obligation quotes from WRAS-approved water softener installers and heating engineers serving Affinity Water Service Area.
Frequently Asked Questions: Affinity Water Water Hardness
Is Affinity Water tap water hard or soft?
Affinity Water tap water is classified as very hard, averaging between 280 and 340 PPM. Over 65% is abstracted from natural chalk aquifers beneath Hertfordshire, Buckinghamshire, and Surrey.
What is the water hardness in Woking?
Woking (GU21/GU22) averages 290 to 310 PPM (very hard). Sourced from Surrey greensand and chalk boreholes blended with Thames water, it forms scale in kettles within days.
What dishwasher salt setting should I use for Affinity Water?
Set your dishwasher water softener dial to H05 or H06 on Bosch/Siemens, or Level 4 on Beko. Running appliances without salt leads to cloudy glasses and heater burnout.
Does Affinity Water cause combi boiler scale?
Yes. Untreated Affinity Water causes a 1.2mm scale layer to accumulate within two years, increasing annual gas bills by £130 to £190 under BS 7593 guidelines.