The process of collecting and using roof runoff, which is also referred to as rainwater harvesting, has been a noteworthy topic among urban planners and water managers over the last couple decades. A study, conducted by Drexel University’s environmental engineers, indicates that if homeowners had a way to collect and store the rain falling on their roofs, they could flush their toilets often without having to use a drop of municipal water. When rain cannot infiltrate into the ground it causes the sewer to overflow, which leads to a discharge of untreated wastewater into local streams and rivers. The research surmised that capturing rainwater can help to reduce the demands on the water treatment system and ensure that it will still function properly even during heavy rainfall events.
Philadelphia would see the largest percentage of runoff reduction if rainwater-harvesting systems were installed in residences citywide. This is because the average roof size in Philadelphia is smaller than the other cities evaluated, equaling less runoff to manage from a single roof. The study also took into consideration the cities’ annual rainfall patterns and residential population. The conclusion was that with enough water storage capacity (a little more than a standard 1,000-gallon home storage tank), an average-sized family would have enough water to cover over 80 percent of its flushes throughout the year.
Philadelphia, looking for though-provoking conversations? Why not attend one of the Initiative seminars at National Mechanics? The next event will discuss changes to the topography of Philadelphia’s surface streams and how they have been channeled underground and incorporated into the city’s 3,000 mile sewer system. ‘Tapping our Watershed’ is a monthly science café in Philadelphia that brings lovers of water science together for conversations with top experts in the field. You can expect to hear engaging talks ranging from water and sewer policy and management to the effect pollutants have on the environment. A Q&A will be included after each presentation.