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Murky waters – what counts as good water quality?

Murky waters – what counts as good water quality?

Flo Bullough discusses the meaning of good and bad water quality, what’s in our tap water and what policies control the content of drinking water.

Pressure on water supply and quality has been high on the public and media agenda over the last 18 months. The widely publicised drought in early 2012, recent reports that we are due to run out of clean water in this generation and the controversy around potential contamination from fracking and the water industry itself have got a lot of people talking about good and bad water quality.

Water is the most important, interesting and unique compound on the planet. In addition to its necessity for all life, it also plays a fundamental role in industry and agriculture. For this reason the provision of reliable supplies of water of an adequate quality is imperative for health and for the economy. Geoscientists and hydrogeologists are involved at many stages in the water provision process, including characterising the geology and geochemistry of groundwater and surface water systems, identifying contaminants and the development of materials for the remediation of polluted drinking water.

Water_cycle BIG

Water carries the signature of the many parts of the water cycle it has passed through and so is never as simple as H2O. Source – USGS, Wikimedia Commons

What’s in our water?

For a water scientist, the purity of water is considered differently depending on its intended use. For the purpose of this post, I’ll be looking at what’s required to make drinking water ‘fit for use’ which applies to all water intended for human use. 100% pure water is the compound H2O, but in nature, however, this doesn’t exist as water acts as the universal solvent and is often a much more complex and heterogeneous mixture of dissolved salts, inorganic and organic compounds and bacteria. This is due in part to the extremely variable nature of the geology and soil that water interacts with. Water is as unique and variable as the geological strata through which it passes creating a fingerprint of the local geology.

The dissolved minerals in water such as magnesium and calcium bicarbonate is what clogs up our kettles! Source -

The dissolved minerals in water such as magnesium and calcium bicarbonate is what clogs up our kettles! Source – Julo, Wikimedia Commons.

It is the impurities it collects along the way that make the difference between hard and soft water; hard water contains more calcium and magnesium bicarbonate (leading to that nasty build up in your kettle!) but has no negative impact on health. Many of these impurities are either completely harmless or exist at concentrations below those posing a risk to health.

Some of these components create better tasting and higher quality water such as a balanced amount of magnesium, potassium, calcium and silica – chlorine, on the other hand, often ruins the taste of water. In addition to the compounds and chemicals that enter the water system in the environment, many water companies also add certain chemicals to drinking water. At the disinfection step, chlorine is often added to remove harmful bacteria, and some of this chlorine remains in the water until the point of consumption to ensure the water remains fresh as it makes its way through the pipe network. An issue of long-standing controversy is the addition of fluoride to drinking water. Fluoride is typically added to reduce tooth decay but its wider impacts have been debated extensively. Fluoride is a complex issue in that it can have beneficial health impacts at low concentrations (0.5 – 1 parts per million (ppm)) but acts as a contaminant at slightly higher doses. The threshold set by the World Health Organisation (WHO) guidelines is currently 1.5 ppm. The intense debate around this has led many countries to stop artificial fluoridation of their drinking water.

Areas with groundwater fluoride concentrations above 1.5ppm. Source - Eubulides, Wikimedia Commons.

Areas with groundwater fluoride concentrations above 1.5ppm. Source – Eubulides, Wikimedia Commons.

It is largely not practiced in Europe with the exception of Ireland, Spain, Switzerland and the UK, where approximately 5.8 million people receive artificially fluoridated water.  This variability in the UK is accounted for by the differing regional policies on fluoridation.

How do we define contamination and where do contaminants come from?


Some water contamination is very colourful and visible such as Acid Mine Drainage seen here in Rio Tinto, Spain. Source – Carol Stoker, NASA, Wikimedia Commons.

Contamination can occur in many forms. It may or may not be visible to the naked eye and it can occur at very low concentrations (in the parts per billion range) or at much higher concentrations. This has implications for the wider public and policy-makers in communicating and understanding the issues around water contamination and decontaminating drinking water since the presence of contamination is often far from obvious. Contamination in drinking water is assigned by threshold values: since at least trace amounts of most elements are found in drinking water due to reasons discussed above. It is only when the concentrations of these chemicals exceed an assigned threshold that there is cause for concern. Contamination is normally defined by comparing concentrations in freshwater to a set of pre-determined evidence-based threshold limits that protect humans, flora and fauna from harmful levels of certain chemicals. These contaminants can come from a wide range of sources: acute spills associated with point sources such as industry, acid mine drainage and landfill – often coined anthropogenic sources – but also natural sources, where contamination is geogenic is origin, i.e. naturally present at elevated of harmful concentrations. Geogenic sourced contaminants can be unleashed through the drilling of wells for groundwater as seen in the arsenic crisis in Bangladesh.

What are the current policies covering water quality and its improvement?


The restriction of pharmaceuticals in drinking water could incur high financial and energy costs. Source – LadyofProcrastination, Wikimedia Commons.

Substances which pose a risk to the aquatic environment are regulated in the Water Framework Driective at EU level and member states are requried to control these substances and prevent concentrations exceeding the threshold limit. There are currently over 50 standards to which drinking water is compared and these are listed by the Drinking Water Inspectorate (DWI) in the UK. The job of the DWI is to ensure that private water companies are producing water to the standards outlined in law. These health-based standards derive from those outlined by the EU in 1998 (with the exception of a few national limits), themselves based on strict guidelines outlined by the WHO. A recent inquiry carried out by the UK Government Science and Technology Committee investigated water quality threshold limits and the potential addition of new chemicals to the list of controlled substances. The main concerns were the inclusion of pharmaceutically-derived products to these legal thresholds, the extent of damage they cause, and the financial and energy costs of treating wastewater to remove them.

Problems with threshold limits

Clearly, the protection and decontamination of drinking water is of high importance in the context of a growing population and environmental change. However, adherence to current limits – which can be prohibitively low – and extension of the controlled substances list has complicated implications. Firstly, threshold limits can be extremely low, sometimes sitting at or below the levels which can be measured with current instrumentation. This can make the monitoring of contaminants both difficult and expensive, particularly in developing coutnries where sophisticated analysis instruments may not always be available. Additionally, many people argue that threshold limits are too low due to their basis on risk-derived limits and the lack of clear or ample toxicological or epidemiological studies to aid in deriving the standard value.

As issues of water and energy provision continue to converge in a difficult economic climate, knock-on impacts to intensive water remediation will only become a more important consideration for decision makers. The challenge now is to effectively communicate and manage the intensifying water issues associated with water security and quality in the light of economic factors, feasibility and the rising cost of energy.

Four degrees: Discussions on climate change, policy, environmental geochemistry and sustainability

As we enter the 400ppm world for the first time in a good chunk of geological history, issues of environment, sustainability and climate change are, more than ever, a source of discussion – and often heated dispute – in the media. As these issues are debated by governments and policy-makers, hardly one day goes by without a series of news articles on topics such as shale gas, warming climate, deforestation or renewable energy, to cite but a few.

View from the Mauna Loa observatory in Hawaii. Photograph distributed under a CC-BY 2.0 license.

View from the Mauna Loa observatory in Hawaii, where atmospheric CO2 concentrations exceeding 400 parts per million were recorded in May 2013. Photograph by Nula666.

According to the recent 2012 World Bank report, some of the consequences of a world 4°C warmer would include extreme summer heat waves, sea level rise which would impact vulnerable coastal states such as Madagascar or Bangladesh, stressed agricultural and water resources and displaced populations. The international community has vouched to limit future warming to 2°C but uncertainties are still large: uncertainties in climate model predictions and in ecosystem response, though the consensus is pretty clear among environmental and climate scientists that humans are driving much of the observed changes, but also uncertainties in what actions leaders will take to meet this aim.

A number of recent environmental policy issues are being debated in governments around the world and have had much coverage in the media: The Keystone XL project has seen a flurry of recent discussion and has been tagged a defining decision in Barack Obama’s environmental legacy. The plan to rescue the European Union’s carbon trading scheme was rejected by the EU commission in April 2013 but might yet be open for another vote. Carbon Capture and Storage, or CCS, is considered an important technology to put in place if carbon emissions are to be slowed down while maintaining fossil fuels as energy sources. Yet, action is slow in Europe and the UK.

While all of these discussions and debates are taking place, scientists around the world continue to carry out their

The Larsen ice shelf in Antarctica, viewed from NASA's DC-8 aircraft. Photograph by Jim Ross for NASA, distributed under a  CC-BY 2.0 license.

The Larsen ice shelf in Antarctica, viewed from NASA’s DC-8 aircraft. Photograph by Jim Ross for NASA.

research and to publish their findings in the scientific literature. Sometimes, such as with climate model research and estimates, publications are quickly picked up by the media and policy-makers and incorporated into the wider discussion. In other cases, it seems that policy-making and scientific research follow parallel routes without much interaction. So where do these issues fit in with the current geo-scientific research?

Four degrees aims to explore topical issues in environmental geoscience and climate change research and consider current themes in environmental policy from an inter-disciplinary perspective. The blog will discuss ideas and concepts from the fields of climate change, policy, environmental geochemistry and sustainability, mixing discussions on the latest developments in scientific research, the scientific concepts behind environmental geoscience and how geoscience problems relate to big environmental issues and feed into politics, policy and governance.

So welcome to Four Degrees. Four degrees of geoscience, four degrees of warming and hopefully a thousand degrees of discussion. We hope you will enjoy it and look forward to your comments!

Flo and Marion