Building

Green, clean and fresh – WC without the flush

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Objectives

• Provide some alternative solutions, such as transformation of toilets with septic tanks into dry toilets, including recycling of brown, yellow and grey water.

Green Value indicator

• CO2 savings
• Eco footprint
• Energy intensity
• Water Consumption by Sector
• Water abstraction rates and water stress

For example, centralized wastewater systems such as sewer systems or septic tanks have high carbon footprints, therefore alternative technologies such as dry toilets which require less drinking water and generate less wastewater can significantly increase carbon savings
According to Sustainable Sanitation Alliance (SuSanA), “to qualify as sustainable sanitation, a sanitation system has to be economically viable, socially acceptable, technically and institutionally appropriate, and protect the environment and natural resources.”

Explanation

In today’s world, you can get a flush restroom experience practically in every office building (although, according to “The United Nations world water development report 2015”, 35,8 % of the world’s population still lacks access to any proper sanitation facilities). However, conventional sanitation systems have their limitations - standard flush toilets are very energy intensive (the use of clean water for the flushing of toilets is the largest form of water waste in domestic consumption and it is estimated that human beings flush away approximately 70 litres of freshwater per person per day through toilet use (Branstrator, 2014; Zaied, 2018)) and have a negative environmental impact.

There are three main reasons to use dry toilets instead of flush ones:

• to reduce water consumption and water waste;
• to prevent the contamination and pollution of surface water, groundwater (potentially affecting drinking water quality), and soil;
• to enable reuse of the human excreta and wastewater as a soil conditioner and fertilizer.

Dry sanitation systems or dry toilets do not use water to treat or transport human excreta – they operate without flush water and without a connection to a sewer system or septic tank. There is a variety of different types of dry toilets. If appropriately designed, these toilets can produce fertiliser without any chemical or other treatment harmful for the environment or human health, as human excreta contain valuable plant nutrients. The yellow water can be reused as a fertilizer if it is collected separately, as it contains the most nutrients among the wastewater. As the soil degradation caused by human activities is alarming worldwide, reuse of brown water as soil conditioner, since it, unlike synthetic fertiliser, contains organic matter preventing soil erosion, must become an everyday practice.

Some practical actions to stimulate the transformation to dry toilets:

• provide general information about sustainable sanitation – benefits of dry toilets for both the environment and human health, as well as how to use them, how they look and that they don’t smell;
• raise awareness on the importance of using dry sanitation systems to reduce water usage through promotional campaigns;
• get informed about the dry toilet producers in your local area and contact them – explore the possibilities of transforming the sanitation system in your office.

PROS/CONS of the action

Pros:

• positive environmental and health effects
• reducing the inefficiency, expensiveness and energy intensity of the widely used flush sanitation systems
• lower water consumption and significantly lower bills in the long term – low operating costs
• generating demand for greener products and services

Cons:

• more planning and potential higher costs at the start of the investment (although in the long term, costs related to dry toilets are significantly lower than the flush ones)
• tackling socio-cultural perceptions and prejudices about handling the human excreta and social representation of dry toilets
• no standard guidelines on dry toilets

Certified

Not Certified

Link to useful sources

Making composting toilets desirable: Tackling resistance to sustainable sanitation practices https://www.lse.ac.uk/

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Demonstration of a new biocide dry toilet with improved functionalities for three specific markets https://cordis.europa.eu

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The world needs more toilets – but not ones that flush https://theconversation.com

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World Toilet Day https://www.worldtoiletday.info/

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KAKIS positive sanitation - introduction video https://youtu.be/Rnk20TQ3SlM

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Resource management sanitation https://cgi.tu-harburg.de

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Sustainable Sanitation Alliance https://www.susana.org

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How Gray Water Reclamation Works https://science.howstuffworks.com

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