Many people are unaware that an effective rainwater harvesting system shouldn't cost much to maintain once installed, and can help to save money by recycling rainwater for irrigation or greywater use while protecting buildings and engineered structures from water damage.
In cities, rainwater harvesting can be incorporated into rainwater drainage projects, so although a cost is incurred at the outset, over time, recycling and reusing rainwater, e.g. for irrigating parks and green areas, save huge amounts of money — especially when compared to the damage caused by flash flooding and overwhelmed treatment plants.