You are Luz Marina Becerra Sanabria, manager of the public-utility company of San Joaquín del Río, a town of 9,200 people in Boyacá, Colombia. The aqueduct's water is not safe, the regulator has given you until October and, before you choose a plant, you have to set how much water the system will be designed for.
The situation
On Monday 13 April 2026 the latest sample leaves the water-quality risk index (IRCA) at 18.7%, medium risk. In February the national utilities regulator gave the town until October to bring it below 5%; if not, rising fines will follow and, at worst, the company will be taken over. A technical audit has already concluded that rehabilitating the 1998 plant is not enough. On 15 July you must hand the technical package to the regional water programme, the Plan Departamental de Agua.
The town sits at about 2,400 metres in a temperate climate: 6,400 people live in the urban core and 2,800 in fourteen rural districts, or veredas, and the population grows about 1.4% a year. The river intake is rated at 18 litres per second (L/s) but delivers 15.2 L/s firm. In March, at the height of the dry season, the peak hour reached about 38 L/s and the urban core was rationed for the first time in six years.
Three figures set the size of everything else. Users receive on average about 135 litres per person a day; for this climate and altitude, the sector's technical regulation (RAS 2017) sets a cap of 130. Non-revenue water (IANC), the water produced and never billed, stands at 38%; the standard allows a design at 25% if there is a credible plan to reduce losses. And the regulation takes a design horizon of 25 years as its reference. The Plan Departamental co-finances up to 60% of the package if the design complies with RAS; the town and the company can put in at most COP 2,400 million of their own.
The mayor, Wilson Ávila Cárdenas, wants the works running before the October 2027 elections. Councillor Hernán Rojas Pinzón has already said he will ask where the loss reduction will come from. Fidelina Suárez, who chairs the community board of Vereda Alta, reminds everyone that 480 uphill households are due to connect in 2027. At 7:40 the phone rings: the mayor wants to know which plant you will propose. In your flow spreadsheet, the demand cell is still blank.