Silica
Cities measured
87
Detected in
87 / 87
Highest
22.4 mg/L — Addis Ababa
Overview
Dissolved silica dissolves from silicate rocks — the dominant mineral family in Sweden's granite bedrock. It is among the most abundant dissolved substances in Stockholm's soft water. At drinking water concentrations, dissolved silica is chemically inert.
Health Relevance
Dissolved silica is not a health concern in drinking water. Some preliminary research suggests silica-rich water (> 30 mg/L) may reduce aluminium bioavailability, potentially offering modest protection against Alzheimer's disease pathology.
Regulatory Limits
Drinking Water Directive 2020/2184
No EU regulatory limit.
Controversy & Contested Science
A 2009 French cohort study (PAQUID) found significantly lower dementia incidence in people drinking high-silica water over 15 years. A 2013 study showed drinking one litre of high-silica mineral water daily for 12 weeks significantly reduced urinary aluminium in Alzheimer's patients. The proposed mechanism — silica binds aluminium in the gut, preventing absorption — is plausible, but the aluminium-Alzheimer's hypothesis itself remains contested. Mainstream Alzheimer's research does not list water silica among priority interventions, and the epidemiological associations have not been confirmed in randomised trials.