Claim Verification: "You need to drink at least 8 glasses of water daily for optimal health regardless of thirst." — Disproved

Automated fact-verification of the claim: "You need to drink at least 8 glasses of water daily for optimal health regardless of thirst." Verdict: DISPROVED Key Findings Three independent authoritative sources were verified that directly reject the claim (threshold: 3 required; 3 confirmed). A 2002 peer-reviewed systematic review in American Journal of Physiology (Valtin) found "rigorous proof for this counsel appears to be lacking" (B1). The National Academies of Sciences, Engineering, and Medicine (the body that sets US Dietary Reference Intakes) explicitly states that healthy people "adequately meet their daily hydration needs by letting thirst be their guide" (B2). Tufts Medical Center clinical dietitian guidance confirms the 8-glasses rule is not a universal requirement: individual needs differ for everyone (B3). Adversarial search found no major health authority (WHO, CDC, NHS) that endorses the "8 glasses regardless of thirst" rule. > Note: 2 of 3 citations (B2, B3) come from domains not yet classified in the credibility registry (tier 2 — unclassified). B1 is a peer-reviewed article indexed on PubMed (tier 5 — government domain). See Source Credibility Assessment in the audit trail. Files proof.py — Re-runnable Python verification script proof.md — Structured proof report proof_audit.md — Full verification audit trail proof_narrative.md — Plain-language summary proof.json — Machine-readable structured data Generated by Proof Engine v1.3.1.