Background to the project


In 2006 CIRIA published guidance document C635 Designing for exceedance in urban drainage – good practice. In 2013, through CIRIA Research Project RP991 Managing urban flooding from heavy rainfall – encouraging the uptake of designing for exceedance, the project investigated the reasons why uptake of the approach has been slow and resources have been developed to help encourage designing for exceedance.


Project outputs

A number of outputs were developed during the CIRIA project to support and encourage practitioners and decision makers to design for exceedance. These were based on extensive consultation with those in the industry, collated case studies and a comprehensive literature review. The outputs are:


Recommendations and summary (CIRIA C738a)


Lessons learnt and success factors (CIRIA C738b)


Collection of case studies (CIRIA C738c)*


Literature review

*Individual case studies can be found here


Please note: this guidance is free to download, but you must sign in to the CIRIA website. 

To complement these outputs a PowerPoint presentation with speaker notes has been produced and can be downloaded here. We also have a number of videos of presentations and interviews providing an overview of drainage exceedance and some case studies, these can be viewed here.

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