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First flush diversion protects your rainwater quality by minimising the volume of suspended and dissolved fine particles that end up in the water you harvest.
A vital part in any Rain Harvesting system, first flush diverters channel, capture and isolate the most contaminated rainwater from your roof in special diversion chambers. You can then manually empty this water or automatically release it into stormwater or your garden.
Generally speaking, the more water you divert, the better the quality of the rainwater that ends up in your tank. However, diverting more rainwater than necessary can lead to volume shortages, so it’s important to calculate your diversion needs, and divert water accordingly.
The following formulas offer general guidelines for calculating how much water you should divert:
This calculation will allow you to determine what length and size pipe or pipes you need for your diversion chambers.