19 February 2022

BFG002: greywater bathroom system

Simple tweaks to existing bathroom features that, because they play such a prominent role in our lives, could significantly improve the way we use water.

• The sink basin drain plug is closed by default, and there is a lever that opens the drain for the duration of the time it’s depressed. When you turn on the tap, the basin fills with water that you can use for washing, shaving, wetting hair, etc. Afterwards, you depress the button and the sink clears. You rinse the basin with the drain open to keep it clean.

  Most contemporary sink drains are open by default. This design nudges us to leave the tap running while we use them, and to use only fresh water. These behaviors are often unnecessary and wasteful, and the above design nudges us in the opposite direction.

• When you turn on the shower, fresh water initially fills up a recirculation system that sends water through the shower head, collects it from the drain, and filters and heats it before sending it back through the head. The shower has an additional lever that you can depress to indicate that fresh water should be used and the recirculation system should be bypassed. When the tap is turned off, this lever automatically resets to use the recirculation system, and that system is drained.

  A lot of our time in the shower is spent washing or just standing under hot water. The above design allows you to use recirculated, lightly filtered water for these activities. Then, just before you leave the shower, you can depress the lever to rinse off with fresh water.

• Wastewater from both the sink and shower is stored and used to flush the toilet.