The new requirements — and how they came about — have developers worried. Arlington’s Department of Environmental Services will require developers to use tools such as water storage tanks to ensure new homes can retain at least 3 inches of rain, which will affect applications submitted after Sept. 13, 2021. Currently, developers are only on the hook to improve the quality of water runoff, using rain gardens, planters, permeable driveways and tree cover. DES staff tell ARLnow the new system will manage more water, protect downhill properties, reduce plan approval times, and give homeowners stormwater facilities that are feasible to maintain. In a statement, staff said the change “reflects future-focused and balanced responsiveness to a diverse customer base that includes downhill neighbors, property owners, and builders.”