How does a borehole work?
For businesses looking to manage their water supply and become self-sufficient, a borehole is one of the obvious propositions.
It enables savings on annual water bills compared to the mains business water supply. A borehole is an excellent investment for businesses consuming large quantities of water regularly.
Here’s how the process of implementing a borehole supply works:
The pre-drilling survey:
Before drilling takes place – a pre-drilling survey must be undertaken. The survey is carried out to cover the following aspects:
- Review the composition of the ground
- Check the ground can be drilled through
- Check if water is present in the ground
- Review the waters depth, quantity, and quality of the water
- Review the possibilities drilling and lining
If the survey is successful, the next step is the drilling and lining process.
Drilling and lining
The drilling and lining stage consists of the following steps:
- A local check for underground utilities.
- Drilling an eight-inch borehole down to the water table.
- Depending on the ground composition, you will need to install a temporary steel casing to prevent collapse during drilling. Then five-inch plastic or steel casing will be slotted to the bottom of the hole.
- Now, you will backfill the gap between the screen you’ve put in place and the borehole walls with recycled glass gravel.
- Finally, you will cement the gap between the pump chamber and walls at the top of the borehole.
Once the initial drilling and lining have taken place, it’s time to test the water quality.
Testing the water quality.
Testing determines your requirements for both the water quality and the correct pump setup. This is done by using a submersible pump to test the flow of water.
The checks include the natural water level, the recharge rate and the quantity of water. It enables you to work out the correct pump size you will need to ensure water is pumped efficiently into your property.
Ensuring the water is tested adequately at this stage is essential. The water from boreholes is usually safe to drink; there are, however, sometimes dissolved minerals and impurities in the water.
To test the water, samples are sent to a UKAS laboratory to establish the purity and existence of minerals and other substances present in the water. After the results from the lab – you will begin to look at the water treatment systems to ensure you comply with UK water regulations allowing you to provide a pure potable water supply.
Once this is achieved, you can move on to designing and testing the water pump system.
Design and test the pump system.
This is a critical element of ensuring that your borehole functions correctly – it is what brings the water to the surface and needs to run efficiently and reliably.
Pumps for boreholes generally range from four to six-inch submersible stainless-steel pumps. Or, high powered circulation pumps and pressure sets can also be used, depending on your circumstances.
An underground well chamber will then be installed above the borehole to protect the equipment – this is a requirement of the private water supply regulations. The submersible well pump is installed into your borehole, deep down into the water chamber.
Depending on your current setup on your premises, there may be a need to install another water tank, with the sizing based on the estimate of daily water usage. These tanks can range up to 20,000 litres.
The treatment of water
Finally, you will need to consider the treatment of the water supplied by the borehole. Usually, the water extracted is perfectly safe to drink; as mentioned above, you need to comply with the UK’s national drinking water regulations – therefore, a water treatment system is required.
Based on the sample received and tested by the UKAS laboratory, a water treatment system will be developed to deal with any irregularities in water content to ensure you have a potable water supply for your business.
The water treatment system will generally include the following:
- UV sterilisers
- Iron and manganese filtration units.
- Reverse osmosis filters
What are the costs to consider when using a borehole as your primary source of water?
The initial costs for a water borehole depend on numerous factors, including the size of the borehole, the quantity, the quality of the ground, and the daily water supply limit.
In setting up a borehole supply source, your business will incur initial costs for:
- Survey – the cost is dependent on the size and quantity of water required.
- Drilling – the cost of a groundwater well is based on a per meterage charge for drilling. These are dependent on:
- Diameter to be drilled
- Depth to be drilled to
- Ground conditions
- Lining and packing the water well – The charge per metre for the supply and installation of the well casing, screen and filter pack is determined by the diameter and materials used for the borehole.
- Wellhead – It’s a requirement for the private water supply regulations, and for a commercial water system, the cost of a wellhead is around £1250.
- Pump system – The cost of your pump system essentially depends on the following:
- Depth of the borehole
Flow of water
- The pressure requirements
- The distance the water has to travel to reach the property.
- Labour – the labour cost depends on the size of the borehole project and how many people you need, and the specialists to implement.
- Water analysis – Water analysis testing costs vary depending on requirements.
- Water treatment – depending on what the water analysis comes back with, you will then alter and build a specific system to manage and filter any impurities in your water supply.
The costs of mains business water rates increase each year. By installing a borehole, your business will avoid paying these rates saving money over the long term. A well-maintained borehole is a cost-effective asset that will pay for itself in reduced water bills over the long term.