At a Glance
Innovative onsite wastewater treatment helps advance policy that opens the door for more sustainable water infrastructure on Bainbridge Island.
Designed in 1968 by noted mid-century modern architect, Hal Moldstad, the Loom House is a 2,000-square foot property on Bainbridge Island, an area where groundwater provides the only source of drinking water. Overlooking the Puget Sound, the property was originally comprised of a main and guest residence (known as the South House and the North House) linked by an outdoor patio. When the homeowners wanted to update the property and add a carport, they did so with a bold ambition: create a home that would restore the land it sits upon and become the first residential remodel to meet the requirements of the Living Building Challenge (LBC), the world’s most rigorous performance standard for buildings. They also wanted to do so affordably, using practices that could be replicated by others.
As the water consultant on a design team led by the Miller Hull Partnership, Biohabitats, developed strategies to ensure that the site’s water infrastructure would respect the existing hydrology of the site while operating within a defined water budget. After developing a site water balance and collaborating closely with the client and design team, Biohabitats developed three separate water systems. First, the site would have a rainwater to potable system that utilizes water collected on the North and South House roofs, sending it to an underground cistern. Water from the cistern is then filtered and disinfected in a mechanical room in the South House and pressurized for distribution throughout both buildings for all water demand (drinking, bathing, laundry and toilet flushing). Second, there is a rainwater harvesting system on the carport roof that directs rainwater into two above ground cisterns, making this water available for watering the adjacent garden. Third, there is an onsite wastewater treatment system that collects and treats all of the wastewater from the North and South Houses. The treatment system provides advanced treatment, using a recirculating textile filter, creating a high quality effluent that is distributed into the site landscaping, through a subsurface drip dispersal system.
The LBC requires that a building treat its own blackwater on site, but City policy required buildings within the sewer service area, like the Loom House, to connect to the sewer main. Undaunted by this challenge, and joined by members of the International Living Future Institute, the organization behind the LBC, the design team met with City officials and asked them to consider changing the policy. They shared plans for a modified septic system, designed by Biohabitats, which would provide additional treatment through a recirculating textile filter before dispersing effluent to a drainfield via drip irrigation. The City responded by passing an ordinance allowing for onsite blackwater treatment, which not only enabled the project to move forward, but opened the door for others on Bainbridge Island to employ an onsite wastewater treatment practice that could help replenish the aquifer, lessen the burden on the municipal sewer system, and ultimately, help protect the Puget Sound.
Coastal, Infrastructure, Water
Todd Vogel and Karen Hust
Bainbridge Island, Washington, United States
- Miller Hull Partnership
- Anne James Landscape Architecture LLC