According to the SDWA, what temperature and duration is required to test TDS by drying a sample to constant weight?

Testing Total Dissolved Solids (TDS) via the drying method requires specific conditions to ensure accurate and reproducible results. According to the Safe Drinking Water Act (SDWA) guidelines, the method specifies that a sample should be dried at a temperature of 180 degrees Celsius for a duration of 1 hour. This temperature is high enough to effectively evaporate the water while minimizing the degradation of any solids present, allowing for precise measurement of the remaining solids once the sample reaches a constant weight.

When the sample is dried under these conditions, the objective is to achieve a state where no further weight changes occur, signaling that all volatile materials have been removed. This step is crucial for ensuring that the measurement reflects only the dissolved solids without interference from residual moisture. Thus, following this guideline provides reliability in the assessment of water quality with regards to TDS levels.