Is a water well or borehole water safer than mains water?
A surprising number of people and businesses are not connected to the public water mains in the UK and rather use water wells, boreholes or springs for drinking water. Reasons range from environmental, financial or simply because they live in an area that is not connected to the water mains. Many people are concerned about chemicals added to water by the public utilities such as fluoride chlorine and phosphates and believe that spring water, well water or borehole water is safer and better for you. Often, however a private water borehole will receive little regulation and provide water that fails tests for wholesomeness and are contaminated with a range of nasty impurities, pathogens and chemicals.
Off-grid lifestyle
Over the last decade there has been a growing popularity in ‘living off-grid’, disconnecting from utilities, connecting with nature and reducing stress. Other drivers such as the cost-of-living crisis are encouraging more people to disconnect and have more control on their financial situation. For many people off-grid living is not a luxury but a necessity due to the location of their property. While there are many modern solutions for heating homes and generating electricity that can be achieved easily, access to safe potable drinking water requires more care and attention. For homes not connected to the public mains provided by the water companies requires establishing a private supply. This requires either access to a spring or water well or drilling a borehole.
In 2023 about 33,000 private supplies provide water to 1.5% of the UK a significant population of nearly 840,000 people. These supplies do not just provide water to domestic users but also commercial properties such as farms and other businesses. To protect public health water produced privately from boreholes, springs or wells is regulated in much the same way as public water provided by the water companies. While it is expected that water delivered from the public mains or a borehole should have the same quality this is often not the case. Alarmingly the drinking water inspectorate (DWI) has found evidence for faecal contamination in nearly 5% of water samples taken from private water supplies compared to 0.01% of tests conducted on public mains.
The right water source
Surface water, such as river water, rainwater, springs or even a water well can be easily contaminated and hence requires careful water treatment and should be regularly tested. Unless you are lucky enough to have a spring on your land, you will need to dig to reach a source of groundwater. A water well with a bucket on a rope is probably the first image that people will think of when asked about extracting water from underground. This traditional technique for producing a source of drinking water requires the well to be dug into porous rock such as limestone or sandstone. These rocks have a structure containing many small gaps and spaces that allows water to filter through it. Surface water passes through the soil and the spaces within the bedrock until it reaches a saturation zone, the water table. In some areas the water level is close enough to the surface that a relatively shallow well can be dug by hand to reach it. Depending on the amount of rainfall and type of rock the depth of the water table can vary during the course of the year and over time, often requiring older water wells to be eventually dug deeper. Climate change and the impact of commercial land use make traditional groundwater wells less reliable and have led to a rise in popularity of borehole water supplies.
Depending on the rock type and grain size, water will be filtered naturally to produce clear water. However just because the water is no longer cloudy or discoloured this does not mean it is automatically safe to drink. A private water well is typically not very deep and can easily be contaminated by surface water. Most famously it was the water well on Broad Street in Soho that was the source of 1854 Cholera outbreak. Using a shallow well therefore requires careful consideration of water treatment to make sure clean water is delivered.
A water borehole provides the same function as a water well but differs in its construction method. Rather than digging by hand (or mechanically), borehole drilling uses a rotary drill to penetrate deep enough to reach groundwater. Although drilling for extraction of oil and gas has been extensively used for generations, the production of water boreholes is relatively new starting only in the 1960s. Large rotary drilling machines are used to produce boreholes that can be up to 1 km deep. In the UK water boreholes range from 6m to 200m to reach groundwater, depending on local hydrology. It is typically a slow process for water to reach an underground aquifer, which allows harmful bacteria to die off providing much higher water quality. When properly lined and maintained the much deeper water boreholes provide cleaner water, free from surface contamination.
Legal requirements
When used for human consumption, water boreholes, wells, and springs are regulated in much the same way as public water mains. For private supplies the system relies on self-regulation by the owners and water testing and inspections are carried out by the local authority. The environmental health staff at the local authority have duty to carry out water quality risk assessments and keeping records. This system aims at making sure safe drinking water is delivered and keeps the user well informed of any potential problems. The DWI scrutinises this process each year providing further diligence and oversight of the system. While local authorities carry out over 200,000 tests annually, nearly 5-fold increase from 2010 that is still much less than would be expected given the number of private supplies in the UK.
You should register your private water supply with the local council’s environmental health department. The supply must be registered if the water borehole or well supplies a rental property, 50 or more people, is part of commercial activity or produces more than 10 m3 of water a day.
Waterborne diseases
Data from local authority testing of water boreholes, water wells and springs used for human consumption have shown an increase in the number of tests containing E. Coli (5%) and Enterococci (6%). These nasty pathogens are evidence of faecal contamination of the water supply, representing a danger to human health. Most worryingly 13% of tests came back positive for coliform bacteria indicating that the water is contaminated from the surrounding environment. Coliform bacteria exist widely in the environment and represents a ‘canary in the mine’, indicating a problem from surface water runoff into the supply, dirt in the water tank or muck in the taps and pipes.
Although correctly maintained water boreholes will be free from surface related contamination, the ground water itself contain contaminants depending on the local geology. High concentrations of uranium and arsenic have been detected in borehole water samples, which breach WHO limits on concentrations. It is therefore critically important that ground water is not just tested for biological contamination, but also a range of chemical elements that can be present. Water testing has shown that the pipework and fittings are responsible for a large number of samples containing elevated concentrations of lead (3%) and nickel (4%).
Making sure the water is safe to drink
Before embarking on installing your own water supply it is advisable to seek professional help. Companies that provide drilling services to produce a deep borehole offer a complete package including a site visit by a geologist to assess the location, the drilling, water treatment and pumping and environmental monitoring. If you have a water source on your land already such as a spring, water well or stream and are thinking of using it as a private supply there are several steps you will need to take. Due to the higher risk associated with faecal contamination, surface water sources such as a water well requires additional actions to prevent pathogens entering the water. These include regular inspection of the source and septic tanks, prevent livestock and manure to be within 50 m of the water source. Other engineering measures also should be considered to limit prevent surface water entering the well or spring collection chambers. These steps are also important to avoid chemical contamination of the water. However, it is important to contact the environmental health department at the local council and have a full risk assessment of the supply. This will also be important for establishing the correct treatment system and monitoring procedures. Treatment can include water filtration, UV disinfection treatment and chemical dosing. The exact treatment that is required will depend on the water source but regular sampling and analysis is critical to monitor the effectiveness and to make sure the water is safe and wholesome.
Deep boreholes will provide safe and clean drinking water but must be carefully installed and maintained. For many people they are the only solution in areas that are not connected to mains water providing a safe and cost-effective solution. A private supply requires continuous vigilance for the quality of the water, something which is taken for granted with mains water.
The Bottom Line
Private water supplies, such as boreholes, wells, and springs, provide an alternative to mains water for many in the UK, driven by factors like off-grid living, cost concerns, and geographical necessity. However, these sources often carry higher risks of contamination, including harmful pathogens and chemicals, due to less stringent regulation and maintenance. While deep boreholes generally offer safer water by avoiding surface contamination, proper installation, regular testing, and effective treatment are essential to ensure safety. For those relying on private water, professional guidance, adherence to local regulations, and continuous monitoring are vital to maintaining a clean and reliable supply.
