Levees can fail because of different types of mechanisms: external erosions, internal erosions, instabilities. These mechanisms can act separately or in a more complex failure scenarios, leading to a breach, a failure of the levee system, and the flooding of inhabited areas. Usually, more than one mechanism can be involved in a breach. As an example, the collapse of a protection revetment can lead to external erosion of the impervious upstream slope of a levee, which can lead to seepage and internal erosion, which can then lead to the breach. In this paper we present methods used in France for failure mode analysis and performance assessment of levees in regard to the main failure scenarios. Our failure mode analysis is briefly presented, as well as three methods for estimating the safety of levees. One of these methods, based on the use of indexes is presented in detail. This index-based method allows to use many different type of data and to combine them in different steps using expert-knowledge based rules: raw data is combined into status indicators representative of geotechnical characteristics of levee segments components, status indicators are combined into functional criteria which represent the performance of a geotechnical function, functional criteria are combined into performance indicators which represent the safety of the levee relatively to a failure scenario.