Water Hardness
What causes hard water? Rainwater is naturally soft. As it passes through the soil and rocks it dissolves calcium and magnesium salts. These salts are the cause of water hardness. Water passing through chalk or limestone areas is harder than water passing through peaty soils or more insoluble rocks such as granite.
There are two types of hardness, temporary and permanent. Temporary hardness is easily removed when water is boiled. It usually leaves a scum on the top of the water. Permanent hardness cannot be removed by boiling.
What problems can hard water cause? Hard water can cause water pipes and appliances such as kettles, boilers and washing machines to scale up. It can also be found around taps and showerheads. If scale collects on heating elements it can shorten the life of the appliance.
Hardness also makes it difficult to produce a lather from soap and washing powders and can lead to the formation of ‘tide marks’ around the rims of sinks and baths.
Occasionally you will see a film appearing on the surface of hot drinks. This is caused by hardness salts being released from the water when it is boiled and is perfectly harmless.
How is hardness measured? Hardness is expressed as the equivalent amount of calcium carbonate (CaCO3) in milligrams per litre (mg/l) or parts per million (ppm). This indicates the amount of scale that will from if all the hardness is precipitated out of the water.
It can also be expressed in a number of other units which are commonly used in appliances such as dishwashers. These are degrees of hardness in Clarke, German or degrees French.
There are no Regulatory limits for hardness. The table below gives an indication of the equivalent levels of calcium and calcium carbonate and the relative degrees of hardness. Water supplied by the Company is classed as moderately hard.
Table 1 Drinking water hardness
| Ca mg/l | CaCO3 mg/l | Degrees Clarke | Degrees French | Degrees German | Hardness |
|---|---|---|---|---|---|
| <30 | <75 | <5.3 | <7.5 | <4.2 | Soft |
| 30 – 60 | 75 – 150 | 5.3 – 10.5 | 7.5 – 15 | 4.2 – 8.4 | Moderately Hard |
| 60 – 120 | 150 – 300 | 10.5 – 21 | 15 – 30 | 8.4 – 16.8 | Hard |
| >120 | >300 | >21 | >30 | >16.8 | Very Hard |
Key: < less than; > greater than; mg/l milligrams per litre.
The table below is a guide to water hardness levels in the South Staffordshire Water area of supply.
To identify which zone you live in:
- 1. Open our Water Quality Zones PDF Document
- 2. Find the code for your area by looking up your nearest town on the list.
- 3. Use the code to find Water Quality Hardness for that area.
| Zone | Zone Name | mg/l or ppm CaCO3 | Degrees Clarke | Degrees French | Degrees German |
|---|---|---|---|---|---|
| BB | Barr Beacon | 245.4 | 17.2 | 24.5 | 13.7 |
| BB1 | Barr Beacon 1 | 240.0 | 16.8 | 24.0 | 13.4 |
| BUR | Burton | 233.2 | 16.3 | 23.3 | 13.1 |
| CH | Cannock High 1 | 208.0 | 14.6 | 20.8 | 11.6 |
| CW | Cawney Hill | 183.1 | 12.8 | 18.3 | 10.3 |
| GLA | Glascote | 242.1 | 16.9 | 24.2 | 13.6 |
| HG | Hayley Green | 173.3 | 12.1 | 17.3 | 9.7 |
| HW | Hopwas | 225.2 | 15.8 | 22.5 | 12.6 |
| RCL | Rugeley Cannock Low | 195.1 | 13.7 | 19.5 | 10.9 |
| SGD | Sedgeley Darlaston | 180.3 | 12.6 | 18.0 | 10.1 |
| SP | Springsmire | 212.3 | 14.9 | 21.2 | 11.9 |
| SU | Sutton Coldfield | 233.2 | 16.3 | 23.3 | 13.1 |
| SV | Shavers End | 188.4 | 13.2 | 18.8 | 10.5 |
| SV2 | Shavers End 2 | 188.5 | 13.2 | 18.8 | 10.6 |
| UTT | Uttoxeter | 253.5 | 17.7 | 25.4 | 14.2 |
| WA | Walsall | 190.2 | 13.3 | 19.0 | 10.7 |
| WA1 | Walsall 1 | 190.3 | 13.3 | 19.0 | 10.7 |
| WB | West Bromwich | 182.4 | 12.8 | 18.2 | 10.2 |
| WIN | Winshill | 284.7 | 19.9 | 28.5 | 15.9 |
|