Greywater Recycling

Of all the water available on Earth, only 3% is freshwater — which we use for everything from drinking to sanitation to farming. Moreover, about two-thirds of that freshwater is locked in glaciers and ice caps, leaving only around 1% of the Earth’s water for us to actually use (Molles, 2016, p.159). Yet, as countries continue to develop and industrialize, the world’s demand for freshwater has increased from about 700 billion m3 in 1901 to 4 trillion m3 in 2014 — a nearly a six fold increase (Our World in Data). Additionally, the amount of freshwater resources per capita — for both the US and the world in general — have been steadily decreasing since 1962 due to our greater use of freshwater and our increasing population’s need of that freshwater (Our World in Data). Because of this, it is crucial to find efficient ways to use the water we have left.

Water storage and preservation has become a concern for architects and urban planners in recent years. Because cities are mainly comprised of impermeable surfaces (i.e. roads, sidewalks, parking lots, and the buildings themselves), only 15% of the precipitation is able to return into the groundwater supply; the majority of the rest runs off into rivers, streams, and oceans, often washing city pollution into these streams as well, illustrated in the figure below (EPS, Protecting Water Quality from Urban Runoff).

However, water that collects from precipitation on the roofs of buildings can be captured and stored in underground tanks or surface ponds so that it can be reused (Acomb and Clark, 2008). It is important to note that although this water can be reused, it is not suitable quality for human consumption since the water isn’t treated. Luckily, the American Institute of Architects (AIA) points out that 95% of commercial water demands are for non-drinkable water uses, so the water that is stored can still be used for supplying water to toilets or for watering plants (Design for Water). By using a mix of recycled water and water from the main system, commercial buildings can reduce their water demand by up to 70% (ESB, Water Recycling Animation).

Therefore, using underground water storage tanks for commercial buildings not only helps to reduce the amount of urban runoff into water reservoirs, but also provides an immediate use of that readily accessible water without relying on the treated, drinking-quality water.

Sources:

Washing dishes is a necessary chore in keeping a home clean. When washing the dishes, many people leave the faucet on throughout the duration of the cleaning process. While this may leave dishes completely spotless, it also wastes a lot of water. On average, hand washing one load of dishes uses 20 gallons of water (Water Footprint Calculator). If you hand wash dishes for three meals every day, you use 60 gallons of water each day washing dishes alone. Annually, this adds up to 7,300 gallons of water. A more efficient way to wash dishes is to use a dishwasher appliance. Not only can dishwashers wash more dishes and silverware at once, water- and energy-efficient dishwaters use as little as 4.5 gallons  per load (Water Footprint Calculator). In comparison to hand washing dishes, dishwashers can wash all of the dishes for the day at once for less than five gallons of water. Using a dishwasher can add up to only 1,642.5 gallons of water per year. On average, this saves 5,657.5 gallons of water each year.

If you do not own a dishwasher and prefer/cannot afford to purchase one, you can still save water while washing the dishes. To do so, be conscious of how much water that is being used. Turn off the faucet after filling up a basin of water to use to clean the load of dishes.

According to the chart above from the Fairview Oregon Official Site, dishwashers only make up 1% of the average household’s water usage. Faucets, on the other hand, make up 19%.  Dishwashers are more water efficient than hand washing dishes, as they use and waste less water. Without the constant running of the faucet, an efficient dishwasher uses only the amount of water necessary to clean dishes. On a domestic level, using a dishwasher to wash dishes can save a significant amount of water.

References:

“Saving Water Indoors.” Saving Water Indoors | Fairview, OR – Official Website, fairvieworegon.gov/492/Saving-Water-Indoors.

“Saving Water While Washing the Dishes.” Water Footprint Calculator, 17 Apr. 2020, www.watercalculator.org/posts/dish-washing/.

Teirstein, Zoya. “Dishwash vs Hand Wash: Which Method Is Better for the Environment?” Grist, 12 Nov. 2020, grist.org/climate/science-dishes-out-an-answer-on-the-old-handwashing-vs-dishwasher-debate/.

Agriculture is one of the most significant users of fresh water in the entire world.  In most countries, agriculture accounts for 70% of the freshwater that is used while in the United States it accounts for approximately 80% of the freshwater used (World Bank, 2017).  With the human population growing at approximately 83 million people each year, the necessity for agriculture and farming increases due to heightened pressures on food supplies (Roser, 2013).  In addition, water is becoming even more scarce throughout the world with about one-fifth of the population lacking safe drinking water.  In conjunction with such immense amounts of water being diverted to the agriculture sector, old and inefficient irrigation systems such as flood irrigation result in large amounts of water being wasted through evaporation (Wired, 2017).  Therefore, more efficient irrigation systems are necessary to reduce water waste and water usage.

One possible improved method of irrigation would be drip irrigation systems.  Drip irrigation systems utilize spray heads and rotors that reduce water output.  The ability of these systems to precisely target areas that need to be irrigated reduce water that is lost to evaporation.  According to Irrigation and Green Industry, drip irrigation systems can save between 30-65% more water than traditional irrigation system.  These systems measure water output in gallons per hour as opposed to traditional systems that measure water output in gallons per minute.  This highlights how great of a water conserver these systems truly are.  Drip irrigation is also considered to be 90-95% efficient than traditional irrigation systems (Irrigation and Green Industry Magazine, 2004).

Drip irrigation systems due however have some downsides.  The reason that they are not readily being implemented is because they are costly to install.  What many do not know though is that their effectiveness at reducing water usage in the longer term is considered to be more cost efficient than traditional systems (Vineyard Team).  While these drip irrigation systems may have their short-term economic downsides, the long-term environmental and economic benefits that these systems provide appear to prove worthwhile.

Works Cited

“Chart: Globally, 70% of Freshwater Is Used for Agriculture.” World Bank Blogs, blogs.worldbank.org/opendata/chart-globally-70-freshwater-used-agriculture.

Drip Irrigation Problems and Solutions, www.vineyardteam.org/projects/Drip-Irrigation-Problems-and-Solutions.php.

“Drip Irrigation:A Water Conserving Solution.” Irrigation and Green Industry Magazine, igin.com/article-218-drip_irrigationa_water_conserving_solution.html#:~:text=When%20used%20to%20water%20plant,percent%20compared%20to%20traditional%20systems.

Roser, Max, et al. “World Population Growth.” Our World in Data, 9 May 2013, ourworldindata.org/world-population-growth.

Staff, WIRED. “Farms Waste Much of World’s Water.” Wired, Conde Nast, 4 June 2017, www.wired.com/2006/03/farms-waste-much-of-worlds-water/.