Water access and availability is becoming an increasing problem throughout the world. However, many places on earth have little to no access to clean drinking water, while other places in the world are wasting clean water. A colleague of mine has just finished her thesis on the achievability of access to clean drinking water in a rural Indian city. In order to achieve this worldwide, the water soft path is proposed as a general pathway to increase water availability and by simply decreasing the demand.
The water soft path is described as the path to managing and reducing the demand side of water in ultra-efficient manners while managing the supply-end at small, regional scales. The water hard path manages water on the supply end on very large scales using capital-intensive methods. There are essentially two actions that can be done on the demand side of water (particularly fresh water) in order to reduce it, such that supply will be able to meet it: 1. Increase efficiency of water use and 2. Reduce consumption.
Firstly, increasing the efficiency of water use would involve several policies and programmes designed to reduce the quantity of water needed to achieve a given task as well as to change the nature of the task to conserve water. These types of policies and programmes could promote the use of low-flow shower heads or sprinklers, measures to plant native vegetation in a given area that therefore, it would not need to be watered other than by natural precipitation. For example, California has adopted different demand-side technologies that have been shown to be cost-effective when compared to the cost of different measures required to increase water supply (the water hard path). Since 80% of the cost of running municipal wastewater systems is associated with the collection and transportation of water, a lot of money can be saved by just using less water to complete the same tasks. California currently has serious issues with water supply due to chronic drought, therefore, taking measures to increase water supply would not only be extremely expensive, but would likely have serious environmental repercussions.
Increasing efficiency is not the only thing that must be done to promote the sustainable use of water. The reduction of consumption is a key measure that must be taken in order to achieve sustainability. There are many things that we use potable water for that lower-quality water can easily do. Approximately, fifty litres of water per person-day are typically needed for an adequate life style, but this amount does not have to be satisfied with high-quality drinking water. For example, flushing the toilet does not need to use potable water, simply because no one is actually drinking it. The sole purpose of using water to flush the toilet is to push the waste down the drain. There are at least two alternatives to toilet flushing that will drastically reduce high-quality water consumption. The first is the use of gray water to flush toilets. This is actually being done at the University of Waterloo in the Environment 3 building. Secondary quality water is being used to flush the toilets, then it is being run through the artificial wetland just outside the building and then through the living wall inside the building. These act as natural filters for the water. Once the water has been filtered, it returns (as secondary quality, non-potable water) to the building to flush the toilets. Gray water can have many other uses, such as: watering lawns, plants or gardens and irrigation of crops. A second alternative to using potable water to flush the toilet is the installation of composting toilets. This is not something new, I have actually seen these used at my summer camp over 10 years ago. I discovered that the reason why they decided to install composting toilets because the sole water source for the camp was one single lake. With thousands of people using this lake year-round, it was crucial to not only reduce water consumption, but also to maintain the quality of the lake and surrounding environment. Nutrient loading of the lake from the use of non-biodegradable soaps and from what went down the toilet was beginning to become a problem before the camp installed composting toilets. At the worst point, while I was there, the lake had its highest levels of blue-green algae and we were told to be careful not to swallow any water while swimming. The next year I returned to the camp to experience these composting toilets and heard about the camp’s reasoning behind their installation. Since then, upon returning to the camp for several years proceeding this, I have not heard of or experienced any significant water quality issues in the lake. From this, it is easy to see how toilets do not need to use any water (directly) at all. These are just two examples from my experience of how wastewater can be used to reduce the demand for high-quality water.
Another issue that I would like to address is that we are taking all these measures to reduce consumption and promote sustainable use of water to achieve a “preferred future water economy.” The question here is: preferable for whom? Clearly, the answer is: for humans. Many of the natural resource commodities are not valued for themselves (inherent value) but because they provide us with services that we want/need as individuals in a society. A system does not really “care” what state it is in, and just like that, the Earth doesn’t “care” what the water supply to humans is in a given area only humans care about this. In the current state of the Earth, the amount of water available in an area has little to do with the demand of the local human population. Therefore, for all humans to have access to potable water, reduction in demand plays a large role, but so does the modification of the water cycle. When I visited the coast of Lima, Peru with Dr. Jeffrey Mackenzie, who specializes in groundwater flow in the Peruvian Andes, I was shown that this area is supposed to be a desert, there is not supposed to be grass and thousands of acres of passionfruit and potato farms. It never actually rains in this area, but still, an immense amount of water is being consumed everyday. This water is coming primarily from the ground as well as glacial meltwater. Excessive/unsustainable groundwater extraction is a large issue in many parts of the world. The groundwater in Lima is likely mostly fossil groundwater since it doesn’t currently seem to have a large recharge rate since there is no rain. An aquifer’s groundwater footprint (GF) is the area required to sustain all current services and ecosystem services . The GF describes the use of the aquifer not its actual size. If the GF/Aa (area of aquifer) is greater than 1, then the aquifer is not being used sustainably and is at risk for saline intrusion and contamination from nearby human activities. Therefore, the preferred water economy being created has a lot to do with the way we modify local ecosystems to meet demand for our desired activities.
In conclusion, the water soft path promotes sustainable water use, which is necessary for the future and for the goal of achieving water security for all. Despite the fact that we are modifying the water cycle in order to achieve water security, the water soft path is way of reducing the impact of our water needs on the planet.
Brooks, D. B., & Holtz, S. (2009). Water soft path analysis: from principles to practice. Water International, 34(2), 158–169. https://doi.org/10.1080/02508060902839940
Gleeson, T., Wada, Y., Bierkens, M. F. P., & van Beek, L. P. H. (2012). Water balance of global aquifers revealed by groundwater footprint. Nature, 488(7410), 197-200. doi:http://www.nature.com/nature/journal/v488/n7410/abs/nature11295.html#supplementary-information