Private Water Supplies

There is recent evidence of the ever-increasing impact of climate change on the sustainable supply of water for homes and businesses in Scotland. The use of private water supplies may indicate a less centralized approach which would reduce stress on the national infrastructure.

Water is an essential element for human life which we take for granted in modern life. The public infrastructure which supplies clean drinking water is complex and requires significant investment and maintenance which is funded through the Scottish Water charge in the domestic council tax bill and business rates.

But there are many locations in Scotland where there is no suitable access to the public water main network. Historically, such locations relied upon natural springs or wells for their water to access the natural reserves of ground water.

In Scotland, the natural environment is shaped by water – you are never very far from a river or loch. However, these resources are subject to the risk of contamination so taking drinking water from them could be harmful to health. A better solution is below ground where water has been naturally filtered through the soil and rock strata. But to access it requires some effort and expense.

There is about an 85% chance that a location will have a useable reserve of water beneath ground, but it is often difficult to accurately predict how far you will have to go down to reach it. This presents some financial risk as the deeper you go, the greater the cost.

A modern drilling rig can be used to drill a narrow diameter borehole which can be anything from 30m to 200m deep depending on where the natural ‘aquifer’ is found. An Aquifer is water below ground which is contained between layers of rock, so to get to the water in it you must drill through the rock above it.

As the borehole is drilled it is lined with lengths of permeable tubing to prevent soil or gravel falling into the newly drilled hole. Once the aquifer is reached, a pump is lowered into the borehole to pump the water to the surface.

The quality of the water in an aquifer depends upon the minerals which exist in the rocks around it. A sample of water is taken from the new supply and sent for testing to determine the level of these various minerals. Small traces are not harmful – the ‘mineral’ water available from the supermarket will contain certain quantities which might give it a distinctive taste.

However, large traces of certain minerals could be harmful to health or may damage the building’s pipework or sanitary fittings. For example, high levels of iron in water will cause red staining – rust – and can give an unpleasant metallic taste to the water.

Once the supply has been tested, the necessary pumping, storage, metering and filtration equipment is installed in a small shed or cabinet at the wellhead. Annual maintenance is required so that the system operates correctly.

It is worth considering the advantages and disadvantages of a private water supply:

  • There are many chemicals, such as chlorine, which are added to the supply from Scottish Water to ensure public health safety, even though chlorine has been found to present an increased risk of cancer and heart disease. Remember that the public water supply comes from naturally occurring open reservoirs and pumped through miles of pipework, so contamination is unavoidable and must be treated. However, a private water supply from a borehole will contain no chemicals.
  • The Scottish Water supply to some rural locations is subject to wide variations in pressure due to demand, so this might require a storage tank and pump to be installed in a remote dwelling to ensure adequate pressure for correct operation of modern plumbing systems.
  • A private water supply is not subject to the water supply charge in the council tax bill or business rates.
  • There is no requirement for Planning consent or Building Warrant approval for a private water supply.
  • The user is responsible for the maintenance and periodic testing of your supply.
  • An electrical supply is required at the wellhead to power the borehole pump and achieve the required pressure for your plumbing and heating system, so any power cut will leave you without water. An alternative could be to use a solar panel and battery.
  • The cost of installing a private supply is significant and should be compared against the cost of connecting to a public main if this is available. There is an element of risk involved as not all locations will have access to a viable private supply and the required depth of the borehole cannot be accurately predicted.
  • The cost can be shared between a number of house plots if there is sufficient flow available from the private supply, and this would reduce the cost to each house of installation and ongoing maintenance and servicing. Where more than one house is connected to the supply, individual flow meters are installed to apportion annual costs appropriately.
  • The use of a private water supply has benefits for sustainability and the environment – it reduces the demand on the public water supply infrastructure, utilises water which is naturally filtered, and is less subject to seasonal weather variations than surface water resources.

Useful Links

https://dwqr.scot/private-water-supplies/installers-or-suppliers-of-pws-equipment/

https://www.highwaterscotland.co.uk/

https://dwqr.scot/private-water-supplies/technical-guidance-and-information/private-water-supplies-technical-manual/

https://www2.bgs.ac.uk/groundwater/waterResources/ScotlandsAquifers.html