Rainwater Drainage Systems

Getting hands-on experience with prototyping has made me pay closer attention to the systems that surround us every day. One that is often overlooked is rainwater collection and filtration. In cities like Boston, rainwater collection systems are designed to channel water off the streets and sidewalks into drains that eventually lead to rivers, harbors, and other natural bodies of water. That system works most of the time, but during periods of heavy rain or overflow, the pipes can flood. When that happens, rainwater mixes with sewage in the same underground system, and the combined waste gets dumped into the environment.

The problem doesn’t stop there. When rainwater runs into drains it is rarely clean. As it travels over asphalt, sidewalks, and rooftops, it picks up whatever is in its path. That can include debris like leaves, sand, or litter, but also chemicals from road salt, oil and grease from cars, fertilizers from lawns, pesticides, cleaning products, and even microplastics. All of these contaminants ride the water straight into drainage systems and eventually into Boston Harbor or nearby rivers. Because there are so many different possible contaminants, it is incredibly difficult to fully control what ends up in natural waterways.

It would be extremely difficult to solve the problem of rainwater mixing with sewage without a large-scale initiative to create new legislation that would set aside funding for remodeling the entire sewage system, but the issue of debris being channeled into the drains by rainwater can be addressed. 

Filters installed in rainwater systems could help capture the larger debris before they ever enter the drainage pipes. The idea of filtering out large debris may have its challenges, but having done some research on the concept, I am personally interested in the topic. To address some of the most common types of debris, designs need to be well thought-out and creatively planned. There are many different variables that need to be addressed.

Macro scale debris: Leaves, trash, and plastics are some of the easiest things to intercept with physical barriers or mesh systems. 

Smaller particles: Sand and sediment could be slowed and settled in catch basins, allowing cleaner water to continue through. 

Micro scale contaminants: For chemicals and smaller contaminants, more advanced filtration materials might be necessary, such as activated carbon layers that can absorb pollutants or biofilters that use plants and soil to naturally treat the water. 

Prototyping these kinds of solutions requires creativity, since filters have to be effective without clogging or demanding constant maintenance. Over time debris may stack up and even block drainage areas, and some designs may need to be replaced or refitted over time.

My Own Experiments 

When I was learning about filtration for rainwater systems, I started thinking about how the natural properties of water could be used to improve designs. One idea I had was to use surface tension and fine mesh materials to let water pass through while holding back other liquids or contaminants. I set up a series of small experiments to see how this could work. While I didn’t land on a perfect solution, it was fascinating to watch how water behaved on different mesh patterns and how oils and other substances separated out instead of blending in. Even without strong success, the process showed me that experimenting with simple concepts can reveal surprising insights. It reminded me that innovation often comes from trial and error, and every test brings you a little closer to a new approach.

Urban water systems may not be the most glamorous part of city life, but they play a huge role in public health and environmental protection. Designing and testing new rainwater filtration methods is one way to address the challenges that come with modern infrastructure. By limiting the amount of debris and contaminants that reach natural water bodies, cities like Boston could reduce pollution, protect ecosystems, and make their urban environments more sustainable. Hands-on experimentation with these systems shows that even small design changes can make a meaningful impact.