Solids in Water|| Water Quality Index || Environmental Engineering || Standards

The term solids in water quality in environmental engineering means the solid matters that can be either suspended or dissolved in water or waste water. The presence of these solids in water in undesirable amounts is unacceptable. 

The Best Levels or Maximum Levels of TDS are different throughout the world and for what application you are using it for. Drinking-Water is basically the same or at least very close to the same no matter the Country because of the standards established by EPA and the (WHO) World Health Organization.

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The solids in water can be:

1. Total Solids'
2. Filterable Solids or total suspended solids
3. Non-Filterable Solids or total dissolved solids

The total solids or total residue in water is the material that is left in a dish after the evaporation of given sample of water and its subsequent drying at a specified temperature. Generally, the drying temperature is between 103 to 105 degrees in oven.

This total solids residue is a combination of total suspended solids (TSS) and total dissolved solids (TDS). TSS in water can be filtered and are also called as filterable solids. While, TDS cannot be filtered and are called as Non-Filterable Solids.

Fixed residue is the residue that is left behind after igniting the total residue for 1 hr at a temperature of 550 ± 50 degrees. The difference between total solids and the fixed solids gives the volatile solids. The solids that are volatized during the process of ignition is called as volatile solids. Volatile solids are generally the organic matter present in water.

As per IS Specification IS: 10500-2012 for water supply the acceptable limit of total solids is 500 mg/l and allowable limit is 1000 mg/l. 

According to EPA, the limit for (TDS) Total Dissolved Solids for Drinking Water in the United States is 500 ppm (Parts Per Million) but normal acceptable Levels range between 300-500 ppm. TDS Listed by EPA as Secondary Contaminants, that may affect how water tastes, and in some cases, cause disease.

Also Read: 

1. Stages of Water Supply System