3" First Flush Device for Downpipe First Flush Diverter Valve – Rainwater Harvesting (WDS99)
The 3" First Flush Device (WDS99) is a vital component of any rainwater harvesting system, designed to divert the first runoff from your roof, which typically contains the highest concentration of dirt, dust, bird droppings, and debris. By isolating this “first flush,” the device protects your tank water quality and reduces sediment buildup.
This diverter is installed at the bottom of a standard 3” vertical downpipe (pipe supplied by others). As rain begins to fall, the device fills with the initial dirty water. Once full, cleaner water is allowed to continue into the storage tank. The unit can be manually flushed as needed between rain events.
Product Details
Key Features
Diverts Contaminated First Rainfall from Entering the Tank
Installs at Base of 3” Vertical Downpipe (pipe by others)
Manual Flush Port for Easy Cleaning
Simple, Reliable, and Maintenance-Friendly
Improves Water Quality and Protects Filtration System
Compatible with Residential and Commercial Systems
Specifications
Part Number: WDS99
Pipe Size Compatibility: 3" Schedule 40 or DWV (pipe not included)
Material: UV-Stabilized Plastic
Mounting: Vertical inline installation
Discharge Type: Manual flush valve
Capacity: Holds first flush volume based on pipe length (typically 1–3 gallons depending on system design)
Application: Rainwater harvesting, roof runoff control, tank protection
Dimensions
Height: ~18 inches (varies based on pipe length)
Diameter: 3 inches (fits standard 3” pipe)
Weight: Approx. 1.2 lbs (without pipe)