At the same time Belgrand began rebuilding the water distribution and sewer system under the streets. In 1852 Paris had of sewers, which could carry only liquid waste. Containers of solid waste were picked up each night by people called "vidangeurs", who carried it to waste dumps on the outskirts of the city. The tunnels he designed were intended to be clean, easily accessible, and substantially larger than the previous Parisian underground. Under his guidance, Paris's sewer system expanded fourfold between 1852 and 1869.