Background: Water hardness varies depending on the source, treatment procedures, and pipeline conditions among others, though not of immediate concern in water quality control but may have significant health, infrastructural, or industrial effects.
Aims and Objectives: This study quantified, classified, analyzed, and compared hardness of tap water samples from household and commercial faucets across the six legislative districts of Manila City, Philippines through complexometric titration.
Materials and Methods: Tap water samples were collected through stratified random sampling, and the hardness was subsequently measured through complexometric titration.
Results: Using the United States Geological Survey Water Quality Information ordinal classification scheme, tap water samples have fluctuating values from soft to very hard qualitative description of the water hardness.
Conclusion: Despite fluctuations in values, water hardness nonetheless passed the 2007 Philippine National Standards for Drinking Water.
Key words: Water Hardness; Complexometric Titration; Manila City, Philippines; Water Quality