Understanding Nutrition: What is considered high sodium in drinking water?

October 24, 2025 •

4 min read

For individuals on highly restricted diets, sodium concentrations in drinking water exceeding 20 milligrams per liter (mg/L) can be problematic. Understanding what is considered high sodium in drinking water is crucial for managing your dietary intake and protecting your long-term health, particularly for those with certain medical conditions.

Quick Summary

High sodium levels in drinking water vary in concern depending on individual health. For those on low-sodium diets, any amount over 20 mg/L requires attention. While not a health threat for most, high concentrations can aggravate conditions like hypertension. Taste perception thresholds are typically higher, so testing is the only sure way to know actual levels. Guidelines from health authorities exist to protect vulnerable populations.

Key Points

High Sodium Defined by Health Needs: What is considered high sodium in drinking water varies based on individual health; for those on strict low-sodium diets, levels above 20 mg/L are considered high.
Taste Isn't a Reliable Indicator: Sodium cannot typically be tasted in water until it reaches much higher concentrations (around 200 mg/L), meaning taste alone cannot determine if a level is too high for a restricted diet.
Specific Health Risks: High sodium from water is a concern for people with hypertension, heart disease, kidney problems, or those on low-sodium diets, as it can worsen these conditions.
Water Softeners Add Sodium: Ion-exchange water softeners increase the sodium content of water, and using an un-softened water source for drinking and cooking is advisable.
Testing is Essential: The only way to confirm your water's sodium concentration is through professional laboratory testing, whether from a public water report or a private well test.
Reverse Osmosis is Effective: Reverse osmosis (RO) is one of the most effective methods for removing sodium from drinking water, filtering 95-99% of it out.

Navigating Sodium in Your Water

While the primary source of sodium in our diets comes from processed foods, drinking water can be a contributing factor, particularly for individuals on sodium-restricted diets. The amount of sodium in tap water can vary widely based on geological location, water treatment processes, and environmental factors like saline intrusion or road salt runoff. Understanding the distinction between levels that are generally acceptable and those that are considered high is the first step toward informed health decisions.

The Lack of a Universal Standard

One of the main complexities surrounding sodium in drinking water is the absence of a single, universally defined standard for what constitutes a 'high' level. Regulatory bodies worldwide and within different regions of the same country have different guidance. For example, the World Health Organization (WHO) does not set a health-based standard for sodium in drinking water, instead recommending a palatability limit of 200 mg/L, as levels above this may be unpalatably salty. In contrast, the U.S. Environmental Protection Agency (EPA) provides advisory guidelines rather than a strict maximum contaminant level (MCL). For those on extremely low-sodium diets, the EPA suggests that levels should not exceed 20 mg/L. Public health officials may be notified when water supplies exceed this threshold to inform sensitive populations.

Why High Sodium in Water Matters for Your Health

For most healthy individuals, the sodium intake from drinking water is a small fraction of their total daily consumption and does not pose a significant health risk. However, certain populations need to be more mindful of this source. These include:

Individuals with hypertension: High sodium intake can elevate blood pressure, putting more strain on the heart and blood vessels.
Patients with congestive heart failure: Excess sodium causes the body to retain fluids, increasing blood volume and placing extra workload on a weakened heart.
People with kidney disease: The kidneys' ability to regulate fluid balance and filter excess sodium may be compromised, making careful sodium management essential.
Those on low-sodium diets: Prescribed dietary restrictions can be undermined by high sodium levels in drinking water, making it difficult to meet health goals.

Long-term exposure to high sodium from water has been linked to adverse health outcomes, including increased blood pressure. A 2025 study in Hypertension even showed a correlation between increased drinking water salinity and elevated blood pressure.

Sources of Sodium in Your Water Supply

Sodium can enter drinking water from various natural and human-caused sources. Identifying the source can influence how you manage the issue.

Natural and Environmental Sources

Mineral Deposits: Water passing through naturally occurring sodium-containing mineral deposits can pick up sodium.
Seawater Intrusion: Coastal areas are particularly susceptible to seawater contaminating freshwater aquifers, leading to high salinity.
Runoff: Road salt used for de-icing in winter can seep into groundwater and surface water supplies, increasing sodium levels.

Treatment and Household Sources

Water Softeners: Standard ion-exchange water softeners replace hard minerals like calcium and magnesium with sodium ions. This can significantly increase the sodium content of your water, especially for households with very hard water.
Water Treatment Chemicals: Chemicals used in municipal water treatment, such as sodium fluoride and sodium hypochlorite, can also contribute to sodium levels, though generally in smaller amounts.

How to Test and Remediate for High Sodium

The only definitive way to know your water's sodium level is through testing, as the taste threshold for sodium is relatively high (often around 200 mg/L), and taste can vary widely.

Steps to Take

Check with your public water supplier: Public water systems are required to regularly test for contaminants, including sodium in some cases, and make this information available.
Test a private well: If you have a private well, you should get it tested by a certified laboratory.
Consider home water treatment: If testing reveals high sodium levels, several methods can be used to reduce them, depending on the scale and source of the problem. Boiling water does not remove sodium; it can actually concentrate it.

Comparison of Sodium Reduction Methods


Method	Effectiveness in Sodium Removal	Pros	Cons
Reverse Osmosis (RO)	95-99% effective	Highly effective, also removes many other contaminants	More expensive than other options, can waste water, often used for point-of-use (e.g., kitchen sink)
Distillation	Very effective	Removes inorganic minerals, effective for multiple contaminants	Energy-intensive, slow process, and can be more expensive to run
Deionization	Effective	Can achieve high purity levels	Uses chemicals for regeneration, typically for high-purity applications, not standard household use
Water Softener (Potassium-based)	Replaces sodium with potassium	Can be a viable alternative to sodium-based softeners	Potassium intake must be monitored for those with certain health issues; consult a doctor

For those with sodium-based water softeners, using an un-softened water supply for drinking and cooking is a simple solution.

Conclusion

What is considered high sodium in drinking water? This question has a nuanced answer that depends on individual health and dietary needs. While levels that affect taste are much higher, the guidance for individuals on low-sodium diets is typically 20 mg/L or less. Understanding your water's sodium content is an important part of managing overall health, particularly for people with hypertension, heart conditions, or kidney disease. Regular testing of your water supply, especially if you have a private well or a water softener, and exploring treatment options like reverse osmosis or distillation can help ensure that your drinking water supports, rather than compromises, your dietary health goals. Always consult with a healthcare provider for personalized advice regarding sodium intake from all sources.

For more information on the impact of sodium on health, a helpful resource is the American Heart Association(https://www.ahajournals.org/doi/full/10.1161/HYPERTENSIONAHA.125.25435?doi=10.1161/HYPERTENSIONAHA.125.25435).

Frequently Asked Questions

No, boiling water does not remove sodium. In fact, it can increase the concentration of sodium in the water because the water evaporates while the sodium remains behind.

For most healthy individuals, the sodium in drinking water is not a health concern because it makes up only a small fraction of their total daily intake. However, different advisory levels exist for taste or specific health needs, such as a 20 mg/L recommendation for those on very low-sodium diets.

Most water softeners work by replacing hard minerals with sodium ions. This process adds sodium to your water supply, with the amount depending on the initial hardness of your water.

You are unlikely to taste sodium in your water unless it is at a very high concentration, often exceeding 200 mg/L, which is the aesthetic objective based on taste perception. The only way to know for sure is to have your water tested.

Individuals on sodium-restricted diets, those with high blood pressure, heart disease, or kidney problems should be particularly aware of their drinking water's sodium content.

The most effective methods for removing sodium from water are reverse osmosis (RO) and distillation. A point-of-use RO system is a common and effective choice for many households.

If you receive water from a public supplier, you can check their Consumer Confidence Report or contact them directly. If you have a private well, you will need to get a water sample tested by a certified laboratory.