Harmaavedellä

Harmaavedellä is a Finnish term that translates to "grey water" in English. It refers to wastewater generated from domestic activities such as washing dishes, laundry, and bathing, but specifically excludes toilet wastewater, which is known as black water. Grey water is generally less contaminated than black water and typically contains fewer pathogens and pollutants.

The composition of grey water varies depending on the source and the products used in cleaning. For instance, grey water from dishwashing may contain food particles and grease, while laundry grey water can contain detergents, fabric softeners, and lint. Bathing water often contains soap, shampoo, and body oils.

In many parts of the world, particularly in regions with water scarcity, grey water recycling systems are implemented. These systems collect, treat, and reuse grey water for non-potable purposes such as irrigation of gardens, flushing toilets, and laundry. This practice can significantly reduce a household's overall water consumption and the amount of wastewater discharged into sewage systems or septic tanks.

The treatment of grey water typically involves filtration and settling to remove solid particles, followed by disinfection if necessary, depending on the intended use. While grey water is generally considered safe for reuse in certain applications, direct consumption or use in food preparation is not recommended due to the potential presence of contaminants and pathogens. The regulatory framework and acceptable uses for grey water vary by location.