The water petal of the Living Building Challenge envisions a future whereby all buildings are designed to harvest sufficient water to meet the needs of occupants, while respecting the natural hydrology of the site, the water needs of neighbors, and the ecosystem it inhabits. With this design approach, the Bullitt Foundation’s new office building has a net-zero water balance and will become the first commercial scale Living Building located in the Pacific Northwest.
We assisted the Bullitt Foundation in meeting the two Water Imperatives of the Living Building Challenge. This integrated design provides the “closed loop” water system required by Imperative 5 and 6 of the Living Building Challenge.
The rainwater falling on a membrane roofing surface is being collected, stored in a cistern, and treated before being pumped to water fixtures to meet the overall water demand. Rainwater collected on-site will supply the building with water for indoor uses and outdoor irrigation. Harvested rainwater is pumped from the cistern, filtered and passed through a ultra-violet disinfection system before reaching the potable fixtures such as bathroom sinks, showers, and kitchenettes. Rainwater intended for non-potable uses (i.e. foam-flush toilets and irrigation) is filtered, but not disinfected, before entering the non-potable water fixtures. Blackwater from the foam-flush toilets, and waterless urinals is treated in basement composting units. The composting units produce a dehydrated, condensed solid. Biosolids may be used as a nutrient rich fertilizer. Greywater is collected in basement holding tanks before treatment. The greywater is treated in a constructed wetland in the building’s 3rd floor green roof area. Following treatment, the treated greywater provides irrigation value and infiltrates into native soils below.