Proper hydration is a fundamental pillar of health. While the need to drink water is universal, determining the “best” type of water is complex, depending on the source, processing, and individual health requirements. Ideal drinking water balances purity, taste, and the presence of beneficial compounds without posing a risk from contaminants. Understanding the differences between common water sources and water quality metrics is the first step toward making an informed choice.
Regulatory Differences: Tap Water vs. Bottled Water
The primary distinction between tap water and bottled water lies in their source and regulatory oversight. Public tap water, or municipal water, is regulated by the Environmental Protection Agency (EPA) under the Safe Drinking Water Act (SDWA). The EPA mandates frequent and rigorous testing for over 90 contaminants, and public water systems must share annual Consumer Confidence Reports detailing water quality.
Bottled water is classified as a packaged food product and falls under the jurisdiction of the Food and Drug Administration (FDA). Federal law requires the FDA’s standards to be at least as protective as the EPA’s, often adopting the same contaminant limits. A significant difference is that the FDA does not require bottlers to test as frequently as municipal systems, nor do they mandate public reporting of test results, resulting in less transparency.
The belief that bottled water is inherently purer is often a misconception, as up to 64% of bottled water can originate from treated municipal sources. Tap water is frequently tested for bacteria several times a day, while bottled water testing frequency can be less stringent. Ultimately, both sources are regulated for safety, but the oversight process and public reporting requirements differ substantially.
Key Metrics of Water Quality: Minerals, pH, and Total Dissolved Solids
Water quality is defined by several measurable physical and chemical properties beyond the absence of contaminants. Total Dissolved Solids (TDS) measures the combined content of all inorganic and organic substances dissolved in water, including minerals, salts, and metals. TDS is a primary factor in taste, with the EPA suggesting an aesthetic guideline of 500 milligrams per liter (mg/L) for optimal palatability.
An elevated TDS level can indicate the presence of harmful heavy metals like lead or arsenic, requiring further specific testing. Conversely, a very low TDS can result in a “flat” or bland taste due to a lack of beneficial minerals. Ideal TDS levels generally fall between 250 and 500 mg/L, providing a refreshing taste while retaining mineral content.
The pH of water measures its acidity or alkalinity on a scale of 0 to 14, with 7 being neutral. The EPA recommends public water systems maintain a pH between 6.5 and 8.5, primarily to prevent corrosion in plumbing systems. Water that is too acidic (below 6.5) can leach toxic metals like copper and lead from pipes, indirectly affecting health.
Minor variations in water pH have little effect on the body’s overall health because the body tightly regulates blood pH at a near-neutral 7.4. Essential minerals, specifically calcium and magnesium, are beneficial for health and contribute to the taste of water.
Evaluating Home Water Filtration Systems
Home filtration systems offer an effective solution for consumers looking to improve their drinking water.
Activated Carbon Filters
Activated carbon filters, found in pitcher and under-sink units, use adsorption to trap contaminants. These filters are effective at removing chlorine, improving taste and odor, and reducing certain volatile organic compounds (VOCs). Carbon filters are a simple, cost-effective choice for municipal water that is safe but has an unpleasant taste.
Reverse Osmosis (RO) Systems
RO systems provide comprehensive purification by forcing water through a semi-permeable membrane (0.0001 microns). RO is excellent for removing virtually all Total Dissolved Solids, including heavy metals, nitrates, and fluoride, with 90-99% efficiency. This technology is also effective for removing emerging contaminants like per- and polyfluoroalkyl substances (PFAS). RO systems require more maintenance and waste a significant amount of water—up to four gallons for every gallon purified—as the membrane flushes contaminants down the drain.
Ultraviolet (UV) Treatment
For households concerned about bacteria, viruses, or cysts, especially those using well water, an ultraviolet (UV) treatment system may be necessary. UV light uses a germicidal wavelength to disrupt the DNA of microorganisms, rendering them unable to reproduce and cause illness, without adding chemicals to the water.
Specialized Water Types and Health Claims
Several specialized types of water are marketed with specific health or purity claims.
Distilled water is produced by boiling water into steam and condensing it back into liquid, removing nearly all dissolved solids and minerals. While exceptionally pure and used for medical equipment, drinking only distilled water is not recommended for long-term hydration because it contributes no beneficial minerals to the diet.
Alkaline water has a higher pH, generally between 8 and 10, achieved through electrolysis or added minerals. Proponents claim it can neutralize body acid and improve health, but scientific evidence supporting these broad claims is limited. Small studies suggest alkaline water may help deactivate pepsin, an enzyme involved in acid reflux, offering a potential benefit for those with digestive issues.
Spring water and mineral water are sourced from underground formations and contain naturally occurring dissolved solids, including calcium and magnesium. Mineral water must contain a specified level of these dissolved solids, which distinguishes it from purified water and provides its characteristic taste. The “best” water balances the removal of harmful contaminants with the retention or reintroduction of beneficial minerals.