Quantifying the first flush phenomenon

Brett Martinson, T. Thomas

Research output: Contribution to conferencePaperpeer-review

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Removing the first millimetres before rainwater is diverted to a store is a much-used method for ensuring high water quality in rainwater harvesting systems. Such first-flush systems rely on the initial rain to partly wash the roof before runoff water is allowed in the store. While there is almost universal acceptance that this is beneficial, there is no agreement on just how much water should be diverted or indeed whether the diversion should be based on volume, depth or rainfall intensity. This paper presents an analysis of first-flush based on theory used for calculating dirt loads in urban drainage. The first flush-phenomenon is found to match that theory, which results in the rule-of-thumb contamination is halved for each mm of rainfall flushed away.
Original languageEnglish
Number of pages7
Publication statusPublished - Nov 2005
Event12th International Rainwater Catchment Systems Conference - New Delhi, India
Duration: 1 Nov 2005 → …


Conference12th International Rainwater Catchment Systems Conference
CityNew Delhi
Period1/11/05 → …


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