Further Reading:
For those interested in learning more about water quality, filtration, and access, here are trusted external sources:

• PubMed – Scientific research on water, health, and filtration
  https://pubmed.ncbi.nlm.nih.gov/
• Drinking Water Inspectorate – UK tap water quality regulations    
  https://www.dwi.gov.uk
• Water.org – Global clean water access initiatives       
  https://www.water.org