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Sodium (salt) in drinking water

See frequently asked questions and answers.


Is sodium found in drinking water?

Yes, low levels of sodium are found in water.  

The MA Department of Environmental Protection (MassDEP) currently requires all water suppliers to inform the Massachusetts Department of Public Health/Bureau of Environmental Health (MDPH/BEH), MassDEP and local Boards of Health when sodium is found in drinking water above a certain level.  This is required so that anyone on a sodium-restricted diet or anyone watching the amount of sodium in their diet for other reasons will have this information.

What is sodium’s purpose?

Sodium is a mineral necessary for normal body function. Muscles and nerves depend on sodium to function.

Where do we get sodium?

We get sodium from our diet.  Fruits, vegetables, meats, dairy, canned foods, processed foods and fast foods all contain sodium. Processed and restaurant foods often contain high levels of sodium.  Sodium is not made or stored in the body.  Drinking water typically adds a small amount of sodium (less than 10%) to a person’s daily intake, which mostly comes from our diet and ranges from:

  • 115 to 750 milligrams per day (mg/d) for infants
  • 325 to 2,700 mg/d for children 
  • 1,100 to 3,300 mg/d for adults

What is the current guideline for sodium in drinking water and who should be concerned about this guideline?

The MassDEP has established a guideline of 20 milligrams of sodium per liter of water (mg/L).  If sodium is measured in drinking water at a level above 20mg/L, it is important for people who may be on a very low sodium or sodium restricted diet to know.

For example, high blood pressure (hypertension) -- a common, chronic medical problem-- is affected by high amounts of sodium. Treatment for high blood pressure includes staying on a diet low in sodium.  According to the National Heart, Lung & Blood Institute of the National Institutes of Health, reducing sodium in your diet not only prevents high blood pressure, but may also prevent heart disease.

People with kidney failure are affected by increased amounts of sodium in the diet.  Kidney failure can happen when too much sodium in the body causes an increase in body fluid.  The kidneys are unable to remove the extra fluid. The result is a kidney shut-down and swelling (edema).  Edema is the collection of water in and around the body tissues. 

How is sodium measured in my body?

Your healthcare provider measures sodium by taking your blood and by checking a urine sample.  If your sodium levels are elevated, you may be put on a low-sodium diet.

Where do I go for more information?

If you have any questions about sodium and your health, call your healthcare provider.

If you have any questions regarding sodium in drinking water, call your public water supplier or the Massachusetts Department of Environmental Protection Drinking Water Program.

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