Alternative water supply options; boreholes are back in vogue!

Until recently, only non-domestic customers in Scotland and very high-level consumers in England and Wales could switch their water supplier to save money or to hope to improve the level of service they receive.

This situation changed in April this year when the water market was deregulated to allow for greater competition in England. About 1.2 million customers are now able to choose their water provider, in the same way as they do for electricity and gas, based on cost and customer service. An objective of deregulation is for (new) suppliers to buy water in bulk from existing major suppliers, and then to sell it on. In such a market, companies might go a step further to offer other utilities, to include gas, electricity, and perhaps telecoms.

Experience from deregulation of the electricity and gas market shows us that there is a lot of inertia involved and that many will take their time to evaluate options before making a significant move.

Scotland deregulated its water in 2008, with customers benefiting from discounted water charges in addition to higher levels of service to help with monitoring and efficiency of water consumption. The latter points are possibly the most important; resulting in greater attention being paid to the value of water, its’ efficient use and consideration of alternative sources of supply – including heightened interest in the very significant cost and other benefits of a borehole water supply.

For consideration of a (borehole) groundwater supply, the main points for consideration include:

  • How much water do you use or need?
  • Would the underlying geology at your site support a borehole water supply?
  • Would the Regulator* of groundwater allow you to consume that amount of water?
  • For your particular process, is groundwater quality directly usable or economically treatable?
  • What maintenance, monitoring and ongoing requirements might there be?
  • How much will this cost, and is there a pay-back?

(*The Regulators are Environment Agency in England, Natural Resources Wales, Scottish Environmental Protection Agency and Department of Environment Northern Ireland).

The first is the easier to answer. A borehole supply should be sized by taking account of average daily and peak-rate consumption (this governs borehole and pump diameters). This information can be ascertained from your existing water supply bills and by monitoring and logging your consumption, ideally at a frequency of 15-minute intervals for at least a week – preferably longer. It goes without saying that in all cases, the primary step is to minimise consumption by implementing widely available efficiency and water-saving devices and processes.

An assessment of underlying geology should be obtained from a professional hydrogeologist with proven experience of providing borehole ‘prognosis’ reports for commercial applications. Their report should include the potential for providing all, or a percentage of, your average daily consumption, the quality of that water and its applicability to your process. For example, not all processes require a quality as high as mains water. The prognosis report should also review the potential drilling risks at your particular location. These might include obvious hazards such as tunnels or old mines – or more complex issues such as the presence of historical contaminants, saline water or artesian flow. With all this information in place, the report should conclude with an outline borehole design, an initial indication of capital cost, predicted running costs and a simple evaluation of pay-back when compared to continued mains water supply.

The cost of a prognosis report will commonly depend on the amount of water to be produced by the borehole – and the worth of that water. For instance a bottled water source would place a far higher value on water compared to, say, water for a farmyard. Should the prognosis prove to be positive and the project proceeds, then further elements of design, specification and tender for a suitable contractor would be required.

For any borehole intended to produce more than 20m3 per day (in England); meeting the requirements of the regulatory process is a significant undertaking requiring the specialist input of a professional hydrogeologist. The objective is to obtain a licence to operate your borehole. This is a valuable document giving you protected, time-limited, legal rights to abstract water. The entire regulatory process from obtaining initial drilling consent to final licensing of your borehole would typically be 9 – 12 months, including the drilling works.

A licence to abstract will be granted on a time-limited basis. The first period will be perhaps 6 – 10 years, depending on the particular catchment the borehole is within. At the end of this period the licence will be renewed for a further 12 years provided there is a proven continued need for water, and the water is used efficiently. Not all areas (catchments) within the UK have ‘new’ water available for consumption due to existing users abstracting the available annual resource. However, in these areas it is sometimes possible to arrange a trade of water rights from an existing licence holder to a new borehole owner.

The quality of water produced by a borehole depends entirely on the underlying geology and characteristics of the aquifer (an aquifer being the porous, permeable rocks that contain the groundwater). Groundwater chemistry and microbiology varies widely as a result of groundwater slowly flowing through the aquifer rocks and ‘absorbing’ minerals specific to that aquifer.

The minerals impart a unique character to that water. Most groundwaters also contain a low level of naturally occurring, harmless bacteria. A ‘Natural Mineral Water’ comes from a registered borehole or spring source and has a chemical (mineral) signature that cannot be changed or treated prior to bottling. Such a water can be highly valuable as a bottled water brand.

Groundwater commonly contains a high concentration of dissolved metals such as iron and/or manganese derived from the rock matrix. Although rarely harmful to health; treatment to reduce the level of iron and manganese is often required prior to using the water for most industrial processes or potable consumption. Industrial and agricultural activity over the last century has added other components to groundwater chemistry that can add to the need for treatment. For example, nitrate is widespread as a result of agriculture, as are a wide range of herbicides, pesticides and industrial chemicals.

Modern water treatment technologies are capable of changing the chemistry or microbiology of a groundwater from its natural state to any desired end point, although the larger number of treatments, or the greater the treatment complexity adds to capital and running costs.

Once your borehole is constructed, tested, licensed and commissioned it will become a vital part of the infrastructure of your business. A borehole is indeed ‘a hole on the ground’ but it is cannot be ignored or put out of mind. In common with all items of infrastructure it requires a level of ongoing planned maintenance and monitoring.

  • Your abstraction licence will require a certain level of monitoring such as water flow rate, totalised volume and depth of water in the borehole.
  • Consistency of water chemistry and microbiology by sampling and laboratory analysis.
  • Monitoring of pump characteristics to forecast potential failure
  • Inspection of the borehole wellhead, chamber, pipeline, valves, sensors for operability and leaks
  • Occasional inspection of the borehole by CCTV (perhaps every 3 – 5 years)

Capital and running costs of boreholes are heavily dependent on required flow rate and the nature of the underlying geology. A borehole located on a good aquifer, and within a catchment with available water, can be shown to pay-back in as little as 2 years when compared to ongoing mains water costs. Extensive treatment plant and/or complex drilling requirements might increase this figure.

Boreholes are now just as often used for access to renewable heating and cooling at all scales – but more detail on this aspect is for another article. A well-designed and constructed borehole might provide continuous service for 50 – 100 years. As a long term, cost saving alternative supply of water; a borehole is certainly worthy of serious consideration.

Written by John Findlay, Director, Carbon Zero Consulting Ltd Tel: 01572 729510