Water hardness
Why some water is hard
If your water comes from underground limestone or chalk rocks, or contains a proportion of groundwater, then the chances are that it is hard. The hardness is caused by the presence of minerals dissolved from the ground and rocks by the water.
If your water is hard you will notice that your kettle and other water heating appliances become furred up with a white scale. You may also find this scale in your bath, sink and shower. It isn't harmful but can be a bit of a nuisance. Hard water can also affect appliances like washing machines, dishwashers and steam irons. Northumbrian Water is compliant with the appropriate regulations and has no plans to introduce softening to hard water areas. Please find below a PDF document of the water hardness for the Northumbrian Water area, along with the measurement of hardness in degrees Clarke, for use with dishwashers and washing machines.
Water hardness by treatment area
This document gives you information on our water hardness broken down by zones, each zone takes its name from the major area supplied. Water hardness does not vary very much, it is relatively constant, the information below is from samples taken in 2010.
Hardness value table
| Description | Hardness in mg/l as calcium (mg/l Ca) |
Hardness in mg/l as calcium carbonate (mg/l CaCO3) |
|---|---|---|
| Soft | 0 - 20 | 0 - 50 |
| Moderately soft | 20 - 40 | 50 - 100 |
| Slightly hard | 40 - 60 | 100 - 150 |
| Moderately hard | 60 - 80 | 150 - 200 |
| Hard | 80 - 120 | 200 - 300 |
| Very hard | Over 120 | Over 300 |
The conversion factors for dishwasher manufacturers are:-
| Total hardness (as mg/l Ca) | x 2.5 = calcium carbonate (CaCO3) mg/l |
|---|---|
| x 0.174 = Degrees Clarke | |
| x 0.25 = French Degrees | |
| x 0.142 = German Degrees |
Northumbrian Water - water hardness zones
| Document | |
|---|---|
| Northumbrian Water - water hardness zones |  |
Northumbrian Water is responsible for supplying a reliable source of safe, clean, drinking water. The majority of the company supply area is soft to slightly hard, and as such we do not change the natural hardness of the region’s water through treatment, it is left to the customer, either domestic or commercial, to decide whether artificial softening is the right choice for them.
There are efficient softening devices available for domestic installation from reputable companies. Most of these work by altering the chemical composition of the water, the calcium and magnesium are substituted with sodium. Northumbrian Water strongly advises that customers keep at least one mains-fed tap in the property for drinking and cooking purposes. This is particularly important for bottle-fed infants and anyone on a sodium-restricted diet*.
Northumbrian Water also advises that any water softening devices are installed and operated in strict accordance with the manufacturers instructions. Further independent advice concerning water softeners and filtration devices can be obtained by contacting British Water at 1 Queen Anne’s Gate, London SW1H 9BT or by visiting their website at www.britishwater.co.uk.
* Many water softeners work by exchanging the calcium and magnesium in the water for sodium.
Contact us to find out more or view the water quality webpage for further information.