Greywater systems utilize and treat domestic wastewater from kitchen, laundry, bath, etc. mainly all wastewater excluding sewer (i.e., waste from toilet that contains fecal matter) for beneficial reuse purposes such as irrigation of landscape plants on a residential scale. Depending upon the scale and complexity of the system, the initial cost and installation of a Greywater System could be as high as around USD $4000, however these systems offer great return of investment particularly with regards to the consumption of water and the amount of water returning to wastewater treatment facilities being reduced which eventually decreases water bills. Greywater systems are designed based on the layout of the site, the number of consumers, and the necessity of the consumers. In other words, what is the purpose of the consumer behind the greywater system installation, if it’s only a secondary means of water supply to the lawn or if it needs to be used for flushing and laundry purposes in which case it would require a more complex plumbing connection. The hot arid temperature conditions in the UAE coupled with population growth, industrialization is putting increasing pressure on supplies of water. Concurrently, a paradigm shift is observed particularly with regards to consideration of ‘waste’ to a ‘resource’ in the water sector when it has been recovered and reused. Greywater treatment offers a creative solution that involves reuse of water that would otherwise be wasted after a single use. Countries such as the UAE receive around 50% of the water production from energy-intensive desalination water treatment plants and the remainder comes from groundwater. Although there is availability of groundwater, it is not substantial and a reliable source of water for the future. Alternative solutions need to be developed to conserve water. Greywater treatment offers a simple and elegant solution to tackle basic water necessities such as cleaning and toilet flushing. Some of the major advantages of greywater include:
- Effective water treatment
- Reduced use of ground and surface water resources for landscape irrigation
- Reduced use of energy and chemicals for water and wastewater treatment
- Improved plant growth
- Reclamation of nutrients (also, reduction of wastewater disposal in rivers/oceans is a significant reduction as a source of pollution)
- Increased awareness of natural cycles and personal water usage
- Landscape irrigation source in preparation for potential future drought irrigation restrictions.
Greywater recycling is an economical method to help consumers reuse wastewater generated at home and thus facilitate water conservations. This episode provides some of the best practical examples of greywater systems available in the market today thus demonstrating its significance as a sustainable solution to the emerging water crisis in UAE. It is the fourth part of a series titled “Residential Greywater Series” by SaniWater. Sani Water has been at the forefront of providing their customers with the latest products and advanced water treatment technologies available in the drinking water industry. With “Residential Greywater Series”, Sani Water aims to educate and inform their customers about the fundamentals of residential greywater, its environmental reuse benefits, and some of the most popular methods of residential greywater reuse available in the market today.
CASE STUDY EXAMPLES OF RESIDENTIAL GREYWATER SYSTEMS
1.Irrigating Vegetables with Laundry Greywater
Figure below shows a picture of greywater harvested tomatoes. These tomatoes were grown using a laundry to landscape the greywater system. After the first growing season with greywater irrigation the owner reported that the vegetables were of great quality. The goal was to replace freshwater irrigation with greywater, give more water to the garden, and save time.
This single-family home has an accessory dwelling unit in the backyard. The house and the secondary unit share a common washing machine. They do up to 6 loads a week. The system irrigates two lemon trees, and two raised veggie beds in the backyard and one fig tree and Japanese maple tree in the front.
Fixtures and output: One top-loading washing machines, about 40 gallons/load, about 6 loads a week= 240 gallons/week
Cost: about $200
2.Planning for Sustainability
The owners of the Cedar Springs Apartments in La Verne, California consider sustainable building practices as an important and integral part of the overall development strategy that includes more than forty properties in and around Los Angeles. Hence, they worked with Biohabitats, an ecologically focused design firm, on a new affordable housing community. The firm recommended an AdvanTex AX-Max unit for the job of treating greywater from residents’ bathroom sinks, tubs, and showers. The high-quality effluent is then reused for toilet flushing and drip landscape irrigation. The housing complex consists of 36 one-, two-, and three-bedroom apartments. Start-up for the property’s AX-Max treatment system was in early 2016, and the unit can handle an average daily flow of 2,660 gpd (10 m3 /day), with a peak design flow of 3,000 gpd (11.4 m3 /day). If the owners ever want to expand the development, another AX-Max can easily be installed to accommodate the increased flows.
- Kobayashi, Y., Ashbolt, N. J., Davies, E. G., & Liu, Y. (2020). Life cycle assessment of decentralized greywater treatment systems with reuse at different scales in cold regions. Environment international, 134, 105215.
- Godfrey, S., Labhasetwar, P., & Wate, S. (2009). Greywater reuse in residential schools in Madhya Pradesh, India—A case study of cost–benefit analysis. Resources, Conservation and Recycling, 53(5), 287-293.
- World Health Organization. (2006). Overview of greywater management health considerations (No. WHO-EM/CEH/125/E).