TDS (Total Dissolved Solids) measures the total concentration of minerals and other dissolved substances in water, indicating its overall purity. A higher TDS level suggests more impurities.
pH measures the acidity or alkalinity of water on a scale from 0 to 14. A pH of 7 is neutral, while values below 7 are acidic, and values above 7 are alkaline. pH doesn't directly measure water purity but can affect taste and the ability to corrode or scale plumbing.