Parts of an Aboveground Gravity Culvert Cistern

A) Header box (for flat roofs): Metal collector to collect rainwater from roof drain/ canale/ scupper and direct it to rainhead screen

B) Rainhead screen: 1/8” screen mesh catches leaves and other roof debris, screen slopes at a 45 degree angle so that debris falls away

C) First flush diverter (optional): Wall-mounted pipe sized to catch the dirtiest water- the first 1% of roof runoff at the start of each storm

D) First flush end cap: Pipe ends at elbow with threaded cleanout cap, with irrigation tube run to vegetation nearby to slowly empty first flush pipe after storms

E) Inflow pipe: Rainfall enters either directly from rainhead screen or once first flush diverter is filled. Typical pipe is painted plastic and sized based on expected rainwater flow calculated from roof area

F) Pitched metal lid: Includes interior foam gasket to ensure tank remains free of algae, bacteria, and insects

G) Observation port: Latched door to allow easy visual access to your stored rainwater at any time

H) Vent: Ensures airflow, prevents a vacuum effect in heavy rain

I) Screws: Lid is secured on tank

J) Overflow pipe: ABS pipe in the tank interior, directs water away when the tank is full during a storm

K) Interior tank sealant: The concrete floor, edge of culvert, pipe connections, and steel seams are coated with a potable-rated liquid rubber formulated for water storage

L) Supply line: Interior 1” PVC pipe extends 4” above the floor of the cistern to avoid sourcing sediment settled on the tank floor

M) Spigot: A full-port (3/4” opening) ensures maximum gravity pressure. The supply line can also be extended to provide spigots in various parts of the yard, or to a pump for greater pressure/ longer distances

N) Concrete foundation: We use a circular form to minimize concrete use, which extends 6” from the culvert on all sides. The culvert is set into the concrete while it is wet, and supported on bricks above a reinforcing steel mesh in the pad

O) Backwater valve: On the end of the overflow pipe, this one-way flap valve ensures that water can exit but nothing can enter the tank

P) Mulched, vegetated basin (recommended): Overflow should be used as a resource, and directed to an area with the capacity to accept predicted cistern overflow and native plants to use it efficiently