Shades of Water

Originally published on Tangible Virtual Water on 04/12/2016.

Water is available on Earth in various forms and sources: oceans, lakes, rivers and streams, snow, glaciers, precipitation, fog, wetlands, underground aquifers…

This post is an opportunity to investigate a little, and clarify the terminology which categorises different types of water and virtual water, to understand how they are affected from human use.

Part of the range of terms attributed to water are divided in colours which somewhat reflect the state of the water in question and are typically attributed to different sources, kinds and uses.

These are: blue, green, grey and black water.


Blue water

Rockström et al. refer to blue water as liquid water in rivers and aquifers, in addition to groundwater, as considered by Hoekstra et al., and lakes and dams, according to Falkenmark et al.


Green Water

Rockström et al. explain green water is “naturally infiltrated rain, attached to soil particles and accessible to roots”.

Blue and green water are closely linked in two ways, mainly: the moisture present in the soil percolates restoring the underlying aquifer, and blue water can be used to supply the lack of green water through irrigation (Rockström et al.)

There are two water complementary flows: the blue water flow through rivers, wetlands and underlying aquifers or groundwater and the green vapour water.

The green water flow is from natural systems (crops, forests…), it evaporates back into the atmosphere and comes back in form of precipitation.

The cycle can then start again.


Grey Water

Jefferson et al. define grey water as arising “from domestic washing operations. As such sources include waste from hand basins, kitchen sinks and washing machines, but specifically exclude foul or black water sources (toilet, bidets and urinals).” […] usually generated by the use of soap or soap products for body washing and as such, varies in quality according to, amongst other things, geographical location, demographics and level of occupancy.”

Grey water is collected from sinks, showers, baths, washing machines, dishwashers and can be distributed with different means, such as distribution of water directly from the sink into the toilet as flushing water, or by treating it and making it suitable for irrigation.

In addition, grey water as its own footprint, which the water footprint website defines as “The volume of freshwater that is required to assimilate the load of pollutants based on natural background concentrations and existing ambient water quality standards. It is calculated as the volume of water that is required to dilute pollutants to such an extent that the quality of the water remains above agreed water quality standards.”

Black Water

Black water is water which has come into contact with fecal matter, which contains harmful bacteria and pathogens.
Unlike grey water, coming into contact with this type of waste means that the water is not able to be reused, for example in irrigation, without the risk of contamination.

Waste water has its quality affected due to human use, from domestic use (grey and black water) to industrial or commercial production.

As mentioned before, we are living within the context of  a water crisis: using as little water and as efficiently as possible is vital.

Water-efficient solutions are available and at times in place.

The image below is an example of a greenhouse village which shows the potential of what can be achieved already.
It is decentralised from an energy and water supply and with a waste and water treatment. This means it is an independent, closed loop system where there is no waste or entropy: everything is a valuable input.

Water is supplied by collecting rain water and is kept in a cycle by treating grey water from the home, which is used for irrigating the greenhouse, itself is a source of energy; black water waste gets treated too and provides soil conditioner.

This introduction to different types of water will be useful when I delve into the cost of meat, in my upcoming post.

In the meantime, more information on types of water, water footprint, virtual water and more and can be found from the water footprint website.


How do you manage your home’s water use?

Do you know of other ways to minimise water loss?


Plastic and water-saving law strikes again!

Originally posted on Tangible Virtual Water – Thursday, 24 November 2016


After my post about legislation as a way to regulate the use of water, and my thoughts on the importance of bottom-up pressure in order to support effective legislative change, an instance of the success of new law implementation came to mind.

In October 2015 a new law was implemented in England.
It requires “large shops in England to charge 5p for all single-use plastic carrier bags.”

Such a simple, straight-forward law, already in place in many nearby countries such as Ireland, Wales and Scotland, was viewed as a potential source of chaos and angered customers by some, but one year on, the results have been very promising.

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Individual vs. Legislative Approaches to Use of Water – Part 2

(Continued from part 1)

After consulting a variety of documents I read through DEFRA‘s (Department for Environment, Food and Rural Affairs) report from March 2016, “Enabling resilience in the water sector” added on Water UK’s website.
In relation to the deregulation plan, point 73 is centred on promoting markets, and water is considered as an asset delivering benefits, improving incentives and facilitating markets.

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Individual vs. Legislative Approaches to Use of Water – Part 1

As you can tell by my previous post as part of blog on the water cost everything has, I believe in everybody’s power to make the most at having their voice heard.

Many people feel that what they can do when it comes to climate change or environmental depletion may be worthless, however I am of the opinion that when each person’s initiatives and actions are combined, the results can be truly meaningful and an aid to spur positive change in mindset, which can result in a lower virtual water footprint.

At the same time, my eyes and mind remain wide open: all it takes is one conversation to challenge my views and encourage me to think differently.

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Your Clothes’ Water Footprint

Aside from needing to fuel ourselves every day with food which includes a very changeable amount of virtual water, another of our quotidian actions consists of wearing some sort of clothing. A couple of recent extracurricular activities shifted my attention back to virtual water within this context.

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What is virtual water, and how can it be tangible?

At the start of the academic year, I looked for a selective module which would include climate change and which would have a more practical approach to learn differently and combine it with last year’s theory.
I selected a module from the Geography department, Global Environmental Change.

In the past months I’ve been learning about global changes our planet is experiencing from a more scientific approach. I really enjoyed that, and it made my mind take a glance at the memories of studying geography in a small classroom that smelled of pencil sharpenings and had a map which read “Jugoslavia”.

As part of this module, each student created a blog on a topic of choice.
I chose mine to be about virtual water, the water which is indirectly needed to make everything we use: from extraction processes, to servicing, to growing food for us or animals that some of us eat. It’s funny that I first got to know about it 5 years ago now, and wrote about it on this blog then.

For my uni module I wanted to bring home the concept of virtual water by making it more concrete, so I called it Tangible Virtual Water.

I will post the articles I wrote for it here too. This was the first post.


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What’s in Your Toothpaste? Different Types of Animal-Free Toothpaste

What’s in your toothpaste?

Ever since starting to eat vegan food, I’ve been on a learning curve of progressive knowledge absorption, finding out so many products I din’t consider to have any animal ingredients, in fact, may have (sweets, alcohol…).

Except from food, I have also been choosing health&beauty products that are vegan, such as face creams, deodorants, body lotions, shower gels, soaps and toothpaste.

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