Purification

"Treatment of water (or sewage) to remove harmful or undesirable physical properties and any harmful and undesirable chemical substances and living organisms." (United Nations Publications, 2013) 

Sources

United Nations Publications. "Glossary of Shared Water Resources (English-Arabic): Technical, Socioeconomic and Legal Terminology." (2013). DOI:https://dx.doi.org/10.18356/70b462ce-en