Your concern about water runoff is very common and important for successful urban gardening. The good news is, yes, there are excellent urban planter boxes specifically designed with built-in drainage trays or integrated drainage systems to solve this exact problem.
These modern planters address runoff in two main ways. The first and most common type features a removable drip tray or a fixed reservoir at the base. This tray catches excess water that drains through the soil, preventing it from staining your balcony, patio, or indoor floor. You simply empty the tray periodically. The second, more advanced option is the self-watering planter box. These have a built-in water reservoir at the bottom, separated from the soil by a platform. The soil draws water up through capillary action (wicking), which drastically reduces surface runoff and provides consistent moisture to your plants.
Using such planters offers key benefits. They prevent messy water stains and potential damage to surfaces, protect plant roots from sitting in constantly soggy soil which causes root rot, and promote healthier plant growth by ensuring efficient water use. For the best results, always use a high-quality potting mix in these containers and check the drainage tray regularly, especially after heavy watering or rain. This simple solution allows you to enjoy a vibrant, green space in the city without the worry of water runoff.