South East Water Water Hardness
Supplying top quality drinking water to 2.3 million customers across south east England. Discover network-wide PPM ratings, chalk aquifer vs reservoir water sources, and local appliance calibration guidelines.
Is South East Water Water Hard or Soft?
Yes, South East Water delivers hard to very hard tap water, averaging 270 PPM (18.9° Clark). Three-quarters of supply is pumped from deep underground chalk and greensand aquifers across the North Downs and Weald.
Primary Abstraction: 75% of drinking water is abstracted from underground chalk boreholes, while 25% comes from surface water reservoirs like Bewl Water and Arlington Reservoir.
Where Does South East Water Water Come From?
Water hardness across South East 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 South East Water include: Maidstone, Basingstoke, Tunbridge Wells, Ashford, Wokingham, Eastbourne. If your water bill comes from South East Water, your tap water is certified by the Drinking Water Inspectorate (DWI) and adheres to all British potable safety standards.
DWI Technical Reference
- Supplier Codesouth-east-water
- Typical Range260 – 310 PPM (mg/L CaCO3)
- Source Classificationchalk groundwater
- Coverage RegionKent, Sussex, Surrey, Hampshire, and Berkshire
Appliance Care & Heating Compliance for South East Water Customers
Descale monthly using food-grade citric acid powder to dissolve calcium crust before it flakes.
Set machine hardness dial to Level 4 or H05. Maintain coarse granular salt in the reservoir.
Inline scale reducers or whole-house softeners are required under Building Regulations Part L for all new boiler installations.
South East Water Network Postcode Outcodes (84)
Search and explore official DWI water hardness readings across all postal districts supplied by South East Water.
Living in a Hard Water Zone (TN9 averages 270 PPM)? Compare Approved Local Installers
Get up to 3 free, no-obligation quotes from WRAS-approved water softener installers and heating engineers serving South East Water Service Area.
Frequently Asked Questions: South East Water Water Hardness
Is South East Water hard or soft?
South East Water delivers hard to very hard drinking water across Kent, Sussex, Surrey, and Berkshire, averaging 270 PPM (18.9° Clark).
Why is water so hard in Kent and Sussex?
The South East sits atop ancient Cretaceous chalk strata and the Wealden Greensand. Rain absorbs high volumes of calcium and magnesium as it filters into regional aquifers.
What dishwasher setting should I use for South East Water?
Calibrate your machine to Level 4 or H05. Always ensure the salt chamber is charged to prevent cloudy mineral film on glasses.
Does South East Water cause limescale damage?
Yes. High mineral density causes rapid limescale encrustation on boiler heat exchangers, shower valves, and immersion elements without approved scale protection.