Official Supplier Data: Severn Trent Water • DWI & BS 7593 Standards

Water Hardness in ST7

Official water quality verdict for outcode ST7: classified as Moderately Hard Water (121.7 PPM), supplied and treated by Severn Trent Water across 6 sectors.

Rating: Moderately Hard Water121.7 PPM • 8.5° ClarkSupplier: Severn Trent Water-39% below UK average
Outcode Mean Hardness121.7 PPM8.5° Clark • Moderately Hard Water12.2°fH • 6.8°dH
Outcode ST7 Household Water Quality Verdict & Practical Advice

Domestic tap water in outcode ST7 is officially classified as moderately hard water, averaging 121.7 PPM (mg/L CaCO₃) or 8.5° Clark, supplied and treated by Severn Trent Water across all 6 postcode sectors (1,356 postcodes). Readings range from 45 PPM (ST7 2) to 160 PPM (ST7 9), showing a local disparity of 115 PPM.

☕ Kettle & Tea Quality:

Gradual chalky ring forms in kettles over 2–3 months. Descale quarterly with citric acid crystals to keep heating elements clean.

🚿 Skin & Bathing:

Moderate mineral content is generally gentle on skin, producing normal lather with everyday soaps and shampoos.

🍽️ Appliances & Salt:

Set dishwashers to H02 – H03 to avoid cloudy glassware, and check boiler inhibitor levels at your annual service.

Local Installer Quote Network

Protect Your Heating & Appliances in ST7 (121.7 PPM): Compare Local Specialists

Connect with certified local plumbers for limescale management and British Standard BS 7593 heating system protection in Severn Trent Water.

Verified Against British Standard BS 7593
WRAS-Approved Water Softeners
100% Free & No Obligation Quotes
vs. UK Benchmark-39% Softervs 200 PPM national average
Boiler Heat Loss4% – 7%Est. thermal heating drag
Kettle DescalingQuarterlyAppliance maintenance cycle
Comprehensive Sector Data Aggregation

Outcode ST7 Water Quality & Mineral Profile

Statistical distribution across all 6 postcode sectors and 1,356 delivery points under Severn Trent Water's catchment monitoring:

Analyzed Sectors61,356 postcodes
PPM Spread (Min - Max)45 – 160Variance: 115 PPM
Predominant ZoneModerately Hard Water0% hard/very hard
Regulating AuthoritySevern Trent WaterDWI Regulated Supply
Hydro MetricOutcode ST7 LevelUK National ReferenceRegional Status
Mean Mineral Density121.7 PPM (8.5 °Clark)200 PPM (14.0 °Clark)-39% below baseline
French & German Scale12.2 °fH / 6.8 °dH20.0 °fH / 11.2 °dHEuropean standard conversion
Catchment UniformityVariable (115 PPM disparity)Regional blending standard6 Sub-catchments
Dishwasher Salt CalibrationH02 – H03Bosch H03 / Beko Level 2Salt required
Regional Hydro-Geological Overview

Water Hardness Breakdown: Outcode ST7

Water hardness isn't identical across every street in ST7—there is a 115 PPM variance between neighborhoods. Residents in sector ST7 2 enjoy the softest water at 45 PPM, whereas taps in sector ST7 9 register the highest mineral load at 160 PPM. This localized disparity occurs because Severn Trent Water blends supplies from different boreholes, rivers, and storage reservoirs depending on elevation and seasonal demand.

Supplies across ST7 are managed by Severn Trent Water through a balanced mix of lowland river abstraction and regional storage reservoirs. Water hardness fluctuates moderately between wet winter periods and dry summer months, averaging 121.7 PPM across all 1,356 local postcodes under strict Drinking Water Inspectorate (DWI) compliance.

Estimated Annual Household Financial Impact

Limescale & Appliance Operating Costs in Outcode ST7

Based on 121.7 PPM mineral saturation (Moderately Hard Water), operating heating appliances across ST7's 1,356 households carries distinct annual economic consequences:

Extra Combi Boiler Gas Cost£40 – £80

Negligible heat exchanger limescale layer; boilers maintain optimal seasonal fuel efficiency.

Dishwasher Salt Requirement4 – 8 kg

Soft water requires minimal or zero softener regeneration salt, cutting annual consumable costs.

Heating Element Degradation4% – 7% thermal drag

Minor scale accumulation over 3–5 operating years.

Regional Comparison

Curious how outcode ST7 compares?

See how the hardest sector in ST7 (ST7 9) compares against central London water metrics.

Compare vs London (SW1A 1)

Softest Sector in ST7

Lowest mineral concentration

Softest
Sector ST7 2361 Postcodes • Soft
45 PPM3.2 °Clark

Hardest Sector in ST7

Highest mineral concentration

Highest Hardness
Sector ST7 95 Postcodes • Moderately Hard
160 PPM11.2 °Clark

Frequently Asked Questions: Water in Outcode ST7

Q: What is the average water hardness in outcode ST7?

Tap water across outcode ST7 averages 121.7 PPM (mg/L), which equals 8.5° Clark, 12.2°fH, or 6.8°dH. It is officially classified as moderately hard water water supplied by Severn Trent Water.

Q: Is water in ST7 harder than the UK national average?

The UK baseline average is approximately 200 PPM. At 121.7 PPM, water in outcode ST7 is 39% softer than the national benchmark.

Q: What dishwasher salt setting is recommended for ST7?

For Bosch, Siemens, and Neff dishwashers in outcode ST7 (121.7 PPM), the recommended softener setting is H02 – H03.

Q: Who manages the municipal water supply in outcode ST7?

Public tap water infrastructure across all 6 sectors in outcode ST7 is distributed and monitored by Severn Trent Water.

All Postcode Sectors in ST7

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