Crawley Water Hardness & Quality Report (2026)
Water Hardness
14.3°Clark20.5°fH11.5°dH
Source
mixed
pH Level
7.8
neutral = 7.0
Lead
0.002 mg/L
✓ Below action level
TDS
457.6 mg/L
Est. Daily Cost
£0.46
energy & soap waste
Source: DWI Data Portal · Updated 2026
0–60
mg/L
Soft
61–120
mg/L
Moderately Hard
121–180
mg/L
Hard
180+
mg/L
Very Hard
Appliance Damage Report
In Crawley, your appliances are currently losing 27% efficiency due to mineral buildup.
| Appliance | In Crawley | Soft Water City | Efficiency Loss |
|---|---|---|---|
| Kettle | 2.9 yrs | 8.5 yrs | -66% |
| Washing Machine | 6 yrs | 12 yrs | -50% |
| Water Heater | 7.4 yrs | 15 yrs | -51% |
Regional Water Comparison
How Crawley compares to its nearest neighbours
| City | Hardness | Clark° | Risk | Source |
|---|---|---|---|---|
| ▶ Crawley, South East | 204.5 mg/L | 14.3° | 🔴 Very Hard | mixed |
| Broadfield, South East | 259 mg/L | 18.2° | 🔴 Very Hard | mixed |
| Horley, South East | 329.5 mg/L | 23.1° | 🔴 Very Hard | mixed |
| Reigate, South East | 219.5 mg/L | 15.4° | 🔴 Very Hard | mixed |
| Redhill, South East | 222.5 mg/L | 15.6° | 🔴 Very Hard | mixed |
National Benchmark
How Crawley compares to the United Kingdom average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ Crawley | 204.5 mg/L | 🔴 High |
| United Kingdom National Avg | 183 mg/L | 🔴 High |
| Livingston Top Rated | 8.5 mg/L | 🟢 None |
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What Makes Crawley's Water Unique?
Local geology and source profile
Crawley, the new town in West Sussex established in 1947 south of Gatwick Airport, is supplied by Southern Water. Supply is drawn from a blend of surface water from the River Mole and River Ouse catchments in the Low Weald — rivers that drain the Wealden greensand and clay plain of Sussex — and groundwater from the Chalk Aquifer of the North Downs and South Downs. Southern Water's supply network in West Sussex serves Crawley from its Weir Wood and Darwell reservoir system in the High Weald, blended with chalk borehole contributions. The Crawley new town development from the 1950s onward required substantial water infrastructure investment in the southern Home Counties, now managed by Southern Water's Sussex operational area. Water is treated before distribution to the Crawley and Gatwick area.
Crawley's hardness of 204.5 mg/L (14.3°Clark) reflects the blend of Wealden surface water and chalk groundwater contributions in the Southern Water supply zone. The Low Weald rivers draining into Weir Wood Reservoir carry water from Hastings Beds and Wadhurst Clay catchments, which contribute moderate dissolved calcium. This is blended with chalk borehole contributions from the North Downs or South Downs flanking the Weald, where Cretaceous Upper Chalk groundwater carries higher calcium concentrations. The blend is classified as moderately hard to hard by the Drinking Water Inspectorate (DWI).
Limescale is a regular household concern in Crawley. At 204.5 mg/L, limescale forms in kettles within three to four weeks and monthly descaling is advisable. Combi-boiler heat exchangers accumulate limescale deposits steadily — annual servicing with a limescale check is important, and fitting an in-line scale inhibitor is recommended. Showerheads, taps, and bathroom surfaces develop consistent limescale deposits requiring monthly attention. Washing-up liquid lathers moderately. Using Calgon monthly in the washing machine and maintaining a regular descaling routine is appropriate for Crawley's moderately hard supply.
Geology & Source: Supplied by Southern Water from the Low Weald catchment and North Downs Chalk Aquifer — Crawley sits on the Wealden Plain between the South Downs chalk and the North Downs, drawing on a blend of surface water and chalk groundwater to produce moderately hard water at 204.5 mg/L (14.3°Clark).