[5] On July 18, 1912, "Obras Sanitarias de la Nación" (OSN) was established by Law 8,889 as part of the first Sanitation Plan of 1909 under the presidency of Roque Sáenz Peña.

After Perón was deposed by the Revolución Libertadora in 1955, the investments decreased abruptly, leaving the preventive maintenance behind.

Since the 1960s, OSN associated with local cooperative companies that supply services to small cities (less than 50,000 people each), decentralising operations.

In 1973, under the Héctor Cámpora administration, a plant was built in General Belgrano to supply areas of the Buenos Aires south region.

The contract set a term of 20 years of concession, then extended during the government of Fernando de la Rúa.

[12] After having found fraudulent invoices for non-existent works carried out and false addresses given,[13] the contract was revoked by the Néstor Kirchner administration in March 2006.