Sodium and chloride are the two halves of ordinary table salt, and together they are the most common reason a customer calls to say the water tastes salty. One of them has a formal number attached; the other carries only a public health advisory. Chloride has a 250 mg/L secondary maximum contaminant level under 40 CFR § 143.3, a taste and corrosion standard. Sodium has no enforceable federal limit, but the EPA advises keeping it to 20 mg/L for people on a restricted diet. If you are not sure what your system is running, check your water system's compliance status free at orevant.com before you read on.
The 250 mg/L chloride secondary standard
Chloride's 250 mg/L secondary maximum contaminant level is not a health limit. It is the level above which water starts to taste salty and to corrode pipes and fixtures, which is why the EPA lists chloride under both the taste and the corrosion categories of the secondary standards. A secondary standard is not federally enforceable the way an MCL is, but a state may adopt it as enforceable, and a salty tasting system generates customer complaints and corrosion work either way. See the difference between an MCL and an action level for how these numbers sit in the rulebook.
See exactly what your system is up against
Search by system name or PWSID and get your EPA violation history, open requirements, and upcoming deadlines in under a minute. Free, no account, no obligation.
Sodium's 20 mg/L advisory and the monitoring rule
Sodium has no enforceable maximum contaminant level, because at drinking water concentrations it is not a health hazard for most people. The EPA's February 2003 Drinking Water Advisory for sodium instead sets two guidance numbers: 30 to 60 mg/L as the range where a salty taste becomes likely, and 20 mg/L for people on a physician prescribed very low sodium diet of about 500 mg per day. Even without an MCL, sodium is not off the books: under 40 CFR § 141.41, a system must monitor sodium at the entry point to the distribution system, annually for surface water systems and every three years for groundwater systems, and report the result to local and state public health officials within three months. That monitoring duty is the part operators most often miss.
Where the salt comes from
Chloride and sodium enter drinking water from four main sources. Road salt is the biggest in snow country: winter deicing washes salt into recharge areas and shallow wells, and the spike shows up months later. Water softener discharge adds sodium and chloride to septic and sewer systems, some of which returns to groundwater. Saltwater intrusion pushes chloride and sodium into coastal aquifers when freshwater is drawn down faster than it recharges. And natural deposits leach both into groundwater in arid and sedimentary basins. A rising chloride trend is often the first warning that one of these sources is moving.
What a small system does about it
Treatment depends on the number and the source. For taste and corrosion control the proven options are reverse osmosis, distillation, and electrodialysis, all of which remove chloride and sodium along with total dissolved solids, though they cost more than the simpler treatments a small system might prefer. Blending a high salinity source with a lower salinity source is the lower cost fix where a second source exists. Where the system's own water softener is the source, switching the resin regeneration from sodium chloride to potassium chloride removes the problem at the point of origin. See how total dissolved solids work and how iron behaves in the same groundwater for the fuller mineral picture.
Why chloride matters for your lead and copper program
Chloride is not just a taste issue. It is a driver of corrosion, and a system that ignores a rising chloride trend can quietly undermine its own corrosion control. Elevated chloride raises the corrosivity of the water, which is exactly the condition the Lead and Copper Rule was built to manage. See what the lead and copper action level means. A secondary standard that looks cosmetic on paper can turn into a primary compliance problem through the plumbing.
Know the number before a customer complains
Chloride and sodium rarely trigger enforcement by themselves, which is why they get ignored until a customer complains about salty water or a pipe fails early. But the number is cheap to know, and the fix is far cheaper before the source moves. The $199 compliance scan maps every monitored contaminant on your system, including chloride, sodium, and total dissolved solids, against the numbers you are actually held to, so you know what to fix first.
Prefer to see the public record first? Check your water system free at orevant.com.
FAQ
Is there a federal limit for chloride in drinking water?
Chloride has a secondary maximum contaminant level of 250 mg/L under 40 CFR § 143.3, which is a taste and corrosion standard rather than a health based enforceable MCL. Some states adopt it as enforceable, so check your state's rules.
What is a safe level of sodium in drinking water?
The EPA's 2003 Drinking Water Advisory recommends 30 to 60 mg/L to avoid a salty taste and 20 mg/L for people on a very low sodium diet. There is no enforceable federal MCL for sodium, but monitoring and reporting are still required under 40 CFR § 141.41.
Why does my well water taste salty?
Salty taste is usually chloride and sodium, and the most common sources are road salt, water softener discharge, saltwater intrusion, or natural mineral deposits. A chloride reading above 250 mg/L is the threshold where taste and corrosion become noticeable.
How do you remove chloride and sodium from drinking water?
Reverse osmosis, distillation, and electrodialysis all remove chloride and sodium. Blending with a lower salinity source is a lower cost option where available, and switching a softener from sodium chloride to potassium chloride removes the source where the softener is the cause.
Sources: 40 CFR § 143.3 (secondary maximum contaminant levels); EPA Secondary Drinking Water Standards (chloride 250 mg/L, sulfate 250 mg/L, TDS 500 mg/L); EPA Drinking Water Advisory on Sodium (February 2003); 40 CFR § 141.41 (sodium monitoring and reporting).