Rainwater Collection, Usage and Recycling to Meet the LBC Water Petal
The Living Building Challenge’s (LBC) Water Petal is focused on redefining how we think about “waste” and to realign how we use water. The petal requirements demand that a project has net-zero water, meaning one hundred percent of a project’s water must be supplied by captured precipitation or other closed loop water systems, or by recycling used project water. The water also must be appropriately purified in order to make it acceptable for human consumption.
Here’s how rainwater will be collected, treated, used and recycled in the Brock Environmental Center in order to help meet the net-zero water requirement.
Rainwater Collection and Treatment System
Rainwater will first be collected in a continuous gutter system attached to the low side of the sloped roof and diverted into a large wooden rainwater collection cistern. The rainwater is then sent to a “vortex filter,” which uses a whirlwind-like motion to separate the clean rainwater from large particulates such as leaves and debris. The rainwater that contains debris is sent directly to the rainwater gardens, while the filtered rainwater is sent into two separate storage tanks.
Once the rainwater is in the storage tanks, the water is circulated through an Ozone Generation system. This process serves to ensure that microbial agents are removed from the water. After this pre-treatment is complete, the water is pumped through a treatment system consisting of filters, ultraviolet lighting and chlorine to make it suitable for human consumption.
In the last stage of this process, the water is transferred to pressurized storage tanks where it is kept until needed by a plumbing fixture such as a sink or water fountain. This entire process requires the Chesapeake Bay Foundation (CBF) to acquire a license from the State to operate a “drinking water” system and also employ and maintain a licensed operator of the system.
As mentioned above, the unfiltered water containing debris from the gutter and cistern system is collected in the multiple “rainwater gardens” located around the perimeter of the building. The gardens are comprised of native and natural vegetation and serve as a collection point for the excess rainwater to pool and evaporate back into the atmosphere.
The rainwater collection and treatment system, as well as the “rainwater gardens” will contribute to meeting the requirements of the LBC’s Water Petal. The next blog will investigate and detail the function of the composting toilets, grey water systems and their critical contribution to the net-zero waste certification of the facility.