Bolivia is one of the poorest countries in South America, and the lmost lacking in sewage treatment plants.
Untreated water flows from houses and factories to the Choqueyapu, Cotahuma and Orkohauira rivers, which extend from La Paz to the southern agricultural centre of the country.
For farmers, the high cost of safe water necessitates the use of untreated wastewater in the cultivation of their crops.
"I know it's dangerous, even for our health, but we have to tend to our fields or else we'll starve," says farmer Richard Mamani Valencia, south of La Paz.
The Environment and Water Ministry says it hopes to change this with the construction of the city's first water treatment plant, but for the time being, most of the products that arrive in the early morning at the markets in La Paz are often contaminated.
"12.5 percent of agricultural products were acceptable; 25 percent were mildly acceptable; and 62.5 percent were rejectable." said a 2013 environmental report by Bolivia's comptroller general.
There are no specific studies available indicating the impact on the health of the population, but the National Institute of Health Laboratories says that 70 percent of acute diarrheal diseases are associated with contaminated food, including vegetables.