Reverse osmosis forces water through a fine membrane, removing a broad range of contaminants — heavy metals, nitrates, forever chemicals, disinfection leftovers, and microplastics. Its trade-off is stripping out magnesium and calcium, leaving mineral-free water. The exposure-reduction case is strong where real contamination exists and minerals are replaced; the longevity payoff remains plausible but unproven. (Full Review)

Protocol

System

Under-sink RO

Multi-stage point-of-use unit for drinking and cooking water

Certification

NSF/ANSI 58

Preceded by sediment and carbon pre-filtration

Remineralization

Post-membrane stage

Restores calcium and magnesium after filtration

Time to effect

Contaminant removal

Immediate

Filtered from the first glass after install and flush

Health benefit

Years

Accrues as cumulative exposure falls

Benefits

High: Reduces lead and toxic heavy metal exposure; reduces nitrate exposure

Medium: Reduces PFAS exposure; reduces microplastic and nanoplastic ingestion; reduces disinfection byproduct exposure

Low: Reduces waterborne pathogen risk; improves taste, encouraging adequate hydration

Speculative: Cumulative longevity benefit from lifetime exposure reduction; reduced endocrine-disruptor body burden

Contraindications

Documented magnesium or potassium deficiency

Advanced chronic kidney disease (eGFR under 30)

Infants fed formula reconstituted with demineralized water

Reliance on fluoridated water as sole caries protection

Key Interactions

Magnesium- and potassium-depleting medications (thiazide and loop diuretics such as hydrochlorothiazide, furosemide; proton pump inhibitors such as omeprazole; some chemotherapy agents)

Over-the-counter proton pump inhibitors and certain laxatives

Whole-house water softening

Risk & Side Effects

High: Removal of magnesium and calcium

Medium: Corrosivity and metal leaching from low-mineral water

Low: Microbial regrowth in poorly maintained systems; fluoride removal and dental caries risk

Speculative: Trace element and iodine depletion; electrolyte imbalance with extreme intake

Monitoring

Marker	Target	Why
RBC magnesium	5.0–6.5 mg/dL	Detects magnesium depletion from mineral-free water and diet
Serum magnesium	2.0–2.5 mg/dL	Screens for overt magnesium shortfall
Blood lead level	Below 1.0 µg/dL	Confirms reduced heavy-metal exposure over time
Urinary arsenic (speciated)	Below 10 µg/L inorganic	Verifies reduced arsenic intake, especially for well users
Serum ionized calcium	4.6–5.3 mg/dL	Tracks calcium status alongside magnesium

Cadence: Product-water total dissolved solids monthly; mineral biomarkers at 3–6 months after switching, then every 6–12 months; source and product contaminant re-testing every 6–12 months

Qualitative Assessment

Taste and water intake — whether cleaner-tasting water increases voluntary daily fluid consumption
Energy and muscle symptoms — cramps, fatigue, or palpitations signaling magnesium or potassium shortfall
Digestive comfort — tolerance of the switch to very low-mineral water
System performance cues — changes in flow rate or taste indicating a membrane or filter needs service

Reverse Osmosis Water Filtration for Health & Longevity

Protocol

Benefits

Risk & Side Effects

Monitoring

Qualitative Assessment