Walmart Launches Passive Irrigation System to Save Water
Walmart reports that they are reducing water use in their garden centers by up to 99 percent in some locations by installing WaterPulse capillary mats. The company estimates that it was using 20,000 to 30,000 gallons of water per day in some stores and will be reducing that to around 400 gallons per day with the new technology.
WaterPulse had been growing their presence steadily in individual Walmart since 2013. This past July, the retail giant announced that it planned to implement the mats in all of its 3,700 garden centers across the U.S. To date, more than 500,000 mats, in excess of 7.3 million square feet, have been delivered to Walmart and installed in more than 3,000 locations.
WaterPulse estimates that a typical retail garden store using watering wands consumes up to 4,000 gallons of water a day, which adds up to 730,000 gallons in a 180-day season. By switching to WaterPulse, the company says that garden stores can reduce that amount to 400 gallons a day or approximately 70,000 gallons over a 180-day season—resulting in a 70 percent reduction in water use and saving 650,000 gallons of water.
The WaterPulse capillary mat is designed to lie beneath soft pots or any pot with holes in the bottom, up to 10 gallons in size. Water flows from a connected hose into emitter tubes embedded in the mat, designed to spread water across the mat evenly. When water comes into contact with the pots and soil, it triggers the process known as capillary action, which is what you witness when water spills onto a napkin and immediately starts spreading. In a similar fashion, soil absorbs water from the mat and makes it available to plant roots. As the plants drink, the soil becomes dry and absorbs more water from the mats. The connected hose can be set on a timer to replenish the mats on a regular schedule.
In a 1995 article in GeoJournal, Gurdev Khush explains that deep roots make for healthy plants that are more efficient at supplying nutrients. WaterPulse believes that watering from below helps create deep roots. “In nature, the roots want to move toward the water source, which is beneath them, so the roots grow downward,” says WaterPulse representative Ryan Croy. “When you water from the top of the soil, you can get roots growing laterally or upwards, which leads to a weaker plant.” Retailers sell plants before they become root-bound, so theoretically, deeper or downward-growing roots in this early part of a plant’s life will set the stage for healthier growth as the plant matures in the end customer’s environment.
The ability to automate the watering of the mats is an additional benefit for Walmart, which will help them reduce the amount of labor spent on manual watering, “Implementing the WaterPulse irrigation mats in our garden centers will help us save millions of gallons of water, improve plant quality, and enable our associates to spend more time where they are needed—helping our customers,” said Marybeth Hays, senior vice president of Outdoor Living and Home for Walmart.
Home gardeners can use WaterPulse mats as well: You can purchase three sizes (starting at $57) at Greenhouse Megastore. To add a degree of automation without having to set up a timed control system, home growers can poke a pin-sized hole in the bottom of a 5-gallon bucket and place it atop a WaterPulse mat. When filled, the bucket will act as a reservoir, with water flowing through the pinhole and spreading across the mat to the soil as needed by the plants.