When it comes to rainwater harvesting systems, modifying barrels and determining overflow options are important factors to consider to fit different sized properties. One interesting statistic is that a 1,000 square foot roof can collect approximately 600 gallons of water from just one inch of rainfall. To modify rainwater harvesting systems, it is important to consider the size and layout of the property, as well as the amount of rainfall in the area. Overflow options can vary depending on the number of rain barrels used and the placement of the barrels. It is recommended to elevate the first rain barrel higher than the second and so on for better flow. Additionally, connecting multiple rain barrels near the top using intake and overflow holes can also improve the flow of water. Modifying the system to fit personal needs can involve adjusting the placement and number of rain barrels, as well as using different types of overflow hoses to prevent overflowing and to lead water away from the home's foundation.