What we throw away at home — oils, detergents, chemicals, medications — doesn't just vanish: it ends up in rivers, lakes, and aquifers that, sooner or later, come back to us. In Mexico, water pollution is not just an industrial problem. When it rains, water carries waste accumulated on streets, sidewalks, and drains — oils, trash, metals, and chemicals — and channels them directly into rivers and lakes. It is also domestic. That is, we pollute not only from our homes but also from public spaces. An action that seems individual and consequence-free — throwing away oil, pouring chemicals, disposing of products without control — becomes a collective problem that impacts health, the environment, and access to water. But here's the most important part: this is a problem we can begin to solve from our daily routines. Not pouring oil down the drain is a simple yet powerful action. We turn on the tap, empty the sink, pull the plug... and assume the problem is solved. In Mexico, there are 2,872 municipal wastewater treatment plants, a relevant infrastructure, but still insufficient given the scale of the challenge and the diversity of contaminants the drainage system receives. The cost of this pollution is not minor either. Discussing the issue with family, teaching children that water is not infinite nor immune to our actions, and understanding that every decision counts. Water management does not depend solely on large-scale projects or government decisions. Many of these compounds reach treatment plants, but not all are completely removed. The National Autonomous University of Mexico (UNAM) has warned that when disposed of in drains or landfills without prior treatment, used oil contaminates water and soil and can even damage land fertility and the food chain. The same applies to detergents, solvents, paints, chlorine, degreasers, or expired medications. The clearest example is cooking oil. Millions of homes every day contribute small amounts of waste that, when accumulated, generate a huge impact. Storing it in containers and taking it to collection centers prevents it from reaching the water. In reality, it's only the beginning. The drain is not the final destination. A common practice is to pour it down the sink after cooking, without considering that a single liter of oil can contaminate up to 40,000 liters of water, according to the Ministry of the Environment of Mexico City. That oil not only clogs pipes. The National Institute of Statistics and Geography (INEGI) reported that in 2023 alone, the cost associated with the depletion of groundwater and the degradation of surface water amounted to 102 billion 29.4 million pesos, equivalent to 0.32% of GDP. And there is something even more alarming: in cities, the drainage system and rain function as a single transport network. It is a transit point. Specialist in environmental management and sustainability. There is a misconception we have normalized for years: thinking that what goes down the drain disappears. In bodies of water, it forms a film that prevents oxygenation, directly affecting fish and other organisms. It starts with the basics: in the way we use and care for the resource every day. The same applies to chemicals: opting for biodegradable alternatives, reducing their use, or disposing of them responsibly can make a significant difference. It is also essential to raise awareness at home. But no.
