A key provider of sanitation services

SIAAP- the greater Paris Sanitation Authority- was established in 1970. It transports and treats wastewater for nine million people in and around Paris, along with stormwater and industrial water, contributing to a thriving natural environment in the Seine and Marne rivers.

SIAAP covers four French departments : Paris, Hauts-de-Seine, Seine-Saint-Denis, and Val-de-Marne, along with 180 municipalities in the Val d’Oise, Essonne, Yvelines and Seine-et-Marne departments, which have signed an agreement with the SIAAP.

The SIAAP board comprises 33 local councilors from the four founding departments.

SIAAP has an annual budget of 1,3 billion euros to provide public services in and around Paris, the European city with the highest population density.

SIAAP and its 1,800 employees manage and operate 440 km of pipes, six treatment plants and 12 stormwater retention basins.

Contributing towards improving the quality of the Seine and Marne rivers

The SIAAP’s main mission is to process the waste water from the Paris urban area to contribute towards reaching the good condition targeted by the framework directive on water (DCE). The achievement of this mission can realized with an optimal capacity of the Seine to accept larger or smaller quantities of pollutants, notably depending on its flow. To optimize the quality of purification of the water produced, the SIAAP is developing and implementing a quality prediction model for the Seine.

36 species of fish recorded in the Seine (compared to 3 in 1970)

Key numbers

public service employees

wastwater treatement plants in the Paris region

2,5 million cubic metres
of wastewater treated each day

440 kilometres
underground wastewater transport system

cubic metres stormwater storage capacity


2 rue Jules César,
75589 Paris CEDEX 12

Tél : 01 44 75 44 75


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The SIAAP’s strategy for an ecological transition towards sustainable development

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