Liquid Waste & Botanical Treatment

Course competency

On completing this course you can design, build, plumb, commission and maintain interior and exterior botanical cells that treat greywater and blackwater on site, reuse treated greywater to flush toilets, and pass conventional plumbing inspection while doing it.

Why this course exists

Course 8 showed a regenerative building using half the fresh water of a conventional one. Nearly half of that saving - 13.68 of 29 gallons per person per day - came from a single line: the toilet flushes with treated greywater instead of drinking water.

This course is how that line becomes true.

That is the honest framing. The water system and the waste system are one system seen from two ends. Design them separately and the numbers in Course 8 do not hold. And the payoff is larger than flush water: a building that treats its own waste needs no municipal sewer connection and no functioning leach field to be habitable, which is what makes housing possible on land that conventional servicing would price out of reach.

The principle that makes this permittable

This system does not replace conventional plumbing. It is added to it.

Every botanical cell sits inside a loop created by valving. Every loop can be bypassed entirely, sending flow straight to a conventional septic tank and leach field. The drain layout, pipe sizes and slopes are ordinary. The system as outlined meets International Building Code.

That is the sentence to lead with in a permit office. Your plumber sees what they expect to see; any locally licensed plumber can install it and pull the permit. The botanical cells are an addition the building can run without - which is exactly why an inspector can approve them.

How the system works

Sinks, showers, tubs
   │
   ├─[3-way diverter]──────────────► conventional leach field (bypass)
   │
   ▼
INTERIOR BOTANICAL CELL  (greywater)
   │  rock bulb · plants · roots · bacteria · oxygenation
   │  peat moss filter → well at the deep end
   │
   ├─ recirculation pump ──► back to the reception box
   │
   ├─ priming pump ──► gWOM ──► charcoal filter ──► TOILET FLUSH
   │
   └─ overflow ──► 3" septic line
                      │
                      ▼
              SEPTIC TANK / PRE-TREATMENT CELL
                      │
                      ├─[3-way diverter]──► conventional leach field (bypass)
                      ▼
              EXTERIOR BOTANICAL CELL  (blackwater)
                      │
                      ├─ priming pump ──► tWOM ──► LANDSCAPE IRRIGATION
                      │
                      └─ overflow ──► septic line or a further cell

Water is used four times: once at the fixture, again through the interior cell's plants, again in the toilet, and again through the exterior cell's plants before reaching the landscape. After the exterior cell, the water tests below measurable nitrate levels.

Course structure