South West Water Water Hardness Report
Supplying 1.8 million residents and millions of seasonal visitors across England's South West peninsula. Discover network-wide PPM ratings, chalk aquifer vs reservoir water sources, and local appliance calibration guidelines.
Is South West Water Water Hard or Soft?
Approximately 85% of South West Water customers receive soft water (30–65 PPM) sourced from Dartmoor and Bodmin Moor granite catchments. Plymouth has some of the purest soft water in England (34 PPM), while East Devon (Honiton, Sidmouth) receives moderately hard groundwater (180–210 PPM).
Primary Abstraction: West Devon and Cornwall draw from high moorland reservoirs (Burrator, Roadford, Stithians). East Devon relies on Otter Valley sandstone and greensand boreholes.
Where Does South West Water Water Come From?
Water hardness across South West 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 West Water include: Plymouth, Exeter, Torquay, Truro, Barnstaple, Penzance. If your water bill comes from South West 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-west-water
- Typical Range30 – 190 PPM (Split between granite moors and East Devon)
- Source Classificationupland granite
- Coverage RegionDevon, Cornwall, and small parts of Dorset & Somerset (Pennon Group)
Appliance Care & Heating Compliance for South West Water Customers
In Plymouth and Cornwall, descaling is rarely needed. In East Devon (EX10, EX14), descale monthly.
Set to Level 1 in Plymouth, Exeter, and Truro. Set to Level 3 in Honiton and Axminster.
Combi boiler scale protection under Part L is only necessary in East Devon. All homes must maintain BS 7593 inhibitor levels.
South West Water Network Postcode Outcodes (113)
Search and explore official DWI water hardness readings across all postal districts supplied by South West Water.
Soft Water Zone Detected (DT7 averages 40.4 PPM): Pure Water Solutions
Because your water is naturally soft, you do not need an expensive salt softener (£1,200+). Explore DIY drinking water filters or compare local specialists for boiler care.
Good News: Your Water in DT7 is Naturally Soft (40.4 PPM) — You Don't Need an Expensive Salt Softener!
Unlike hard water regions, you won't suffer from rapid limescale buildup. However, many residents in South West Water Service Area install targeted under-sink filters for chlorine and microplastics, or schedule British Standard BS 7593 anti-corrosion heating maintenance.
Under-Sink Activated Carbon Filter
Removes chlorine taste, odours, lead and microplastics directly at your kitchen tap while preserving healthy natural minerals.
- DIY installation in 15–20 minutes
- No wastewater or electricity needed
- 6 to 12-month cartridge lifespan
Lead-Free Inox 304 Drinking Tap
Dedicated drinking water faucet forged from food-grade 304 stainless steel, preventing heavy metal leaching from older pipework.
- 100% lead-free SUS 304 stainless steel
- Drip-free ceramic disc valve cartridge
- Standard 1/4" push-fit pipe compatibility
KDF-55 Shower Chlorine Filter
Neutralises harsh municipal chlorine and heavy metals that trigger dry itchy skin, scalp irritation, and eczema in soft water areas.
- KDF-55 + Calcium Sulfite media
- Universal 1/2" thread screws onto any shower
- Maintains full water flow and pressure
Prefer professional installation or boiler protection in South West Water Service Area?
Frequently Asked Questions: South West Water Water Hardness
Is South West Water tap water hard or soft?
For the vast majority of Devon and Cornwall, tap water is naturally soft (35–65 PPM). Only localized areas in East Devon (Honiton, Axminster) experience moderately hard water from sandstone boreholes.
Why is Plymouth water so soft?
Plymouth's supply comes from Burrator Reservoir on Dartmoor, where rain falls over ancient impermeable granite tors, absorbing almost zero calcium carbonate.
Do I need a water softener in Devon or Cornwall?
In Plymouth, Exeter, Torbay, and Cornwall, no. You only need to consider a water softener if you live in the East Devon groundwater zone (EX10, EX12, EX14).
What dishwasher setting should I use in Exeter?
Exeter averages 50 PPM (soft). Set your dishwasher to Level 1 or H01 to prevent unnecessary salt consumption.