It is well known that the majority of Britain’s population lives in ‘hard water’ areas. These are mostly in the southern half of the country and as this contains London and its hinterland, as well as Birmingham, it may come as little surprise that this accounts for 60 per cent of the UK water supply.

A key difference, of course, is that while people in the north get most of their water from reservoirs amongst the high moors and mountains, further south a lot more comes from groundwater. This is not just about having less rainfall on gentler topography; the uplands of southern England include a lot of chalk downs, adding dissolved calcium to the supplies emerging from your taps.

If ever proof was needed of the benefits of using water softeners in Berkshire, a survey by Scaleguard has found the places with the hardest water of all. Berkshire was second only to Bedfordshire on a county-by-county analysis, while the league table of towns and cities with the hardest water put Reading and Slough among the top eight.

Perhaps surprisingly, the latter list put Bristol top, followed by Bath, even though adjacent Gloucestershire was just seventh on the county hard list and Somerset not at all. This suggests those cities are hard water hotspots – literally so with Bath’s thermal springs – while Berkshire has a more general hard water issue.

As Southern Water states, 70 per cent of the water supply in the south east comes from chalk aquifers, with 23 per cent from rivers and just seven per cent from reservoirs. However, this differs significantly from one location to another. For example, while Andover and Brighton use 100 per cent groundwater, 79 per cent of Hastings’ supply comes from reservoirs.

This is why, even within a hard water region, there are differences in hardness between cities, towns and counties.