Grout is the substance used to fill the gaps between wall or floor tiles -- to provide stability for the surface and to add flexibility to the design. When you are grouting it is necessary to use a fair amount of water, both for mixing the grout as well as for rinsing the area clean once you have finished. If you do not dispose of the wastewater correctly but allow it to run off into your yard or the street, it may soak through the ground into the water table. This can have a significant impact on the quality of your groundwater.
Tile grout contains the same ingredients as concrete -- namely cement, water and aggregate. Concentrations of the ingredients differ, however, which gives grout more flexibility than concrete. The cement contains a mixture of powdered lime, clay and minerals such as chromium, barium and calcium carbonate, some of which can be harmful to both humans and animals.
Contaminants such as tile grout enter groundwater by several methods, including rivers and rainwater runoff. The most common method is leaching, which is the passage of a dissolved substance through the soil into the water table. The concentration of the contaminant that reaches the water table depends on the original strength of the substance, its persistence and solubility. Contaminants that dissolve easily in water are less likely to encounter resistance on their way through the soil and therefore more likely to reach the groundwater. The persistence of a contaminant depends on how long its chemical properties take to break down.
Tile grout is mildly toxic, based on its cement content and mineral ingredients. Limestone is not toxic for ingestion but does have dermal toxic qualities, which means that it burns the skin. This is evident by the concrete burns sustained by construction workers exposed to cement powder and uncured concrete. Chromium, although a naturally occurring element, is harmful in certain concentrations. For example, continued exposure to chromium produced synthetically can cause a variety of symptoms including vomiting, diarrhea, ulcers, kidney or liver damage, convulsions and death.
The effect of tile grout on groundwater, therefore, is to make the groundwater unsafe for consumption and other uses. Groundwater often mixes with residential water supply facilities through the movement of rivers and excess rainwater, and these facilities provide the water that supplies homes. Although the water goes through an intensive purification cycle before reaching your household, the process is unable to remove all contaminants. Both barium and chromium contaminants are inorganic chemicals found in drinking water in the United States, according to the U.S. Environmental Protection Agency.
- Mine-Engineer.com: Cement, How it is Produced
- Toxicology and Industrial Health: The Dermal Toxicity Of Cement
- U.S. Geological Survey: Water Science for Schools -- Groundwater Quality
- University of Arizona Agricultural Extension: Water Quality and Use -- Sources and Mechanisms of Groundwater Contamination
- Cleary Material Safety Data Sheet: Limestone F
- National Library of Medicine: Tox Town -- Chromium
- U.S. Environmental Protection Agency: Drinking Water Contaminants
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