Minerals and water character
The minerals in tap water, such as calcium, magnesium, sodium, sulfate and chloride, come from the rock and soil the water passed through. A home water test reports 17 of these readings, including pH and dissolved solids. None of them is a health flag on your report. A few carry comfort lines for taste, scale and pipes, such as sulfate above 500 mg/L.
how minerals count on your report
Comfort, not health
None of these readings is ever a health flag. The few with a comfort line tell you about taste, scale and your pipes.
Minerals and water character: what is it, and where does it come from?
Every tap carries dissolved minerals.
Rain and river water pick up calcium, magnesium, sodium, potassium, sulfate and chloride as they move through rock and soil, and carbonate rock such as limestone adds bicarbonate, which is most of what a lab calls alkalinity.
Treatment and plumbing add a little more: utilities raise pH on purpose so the water is gentler on pipes, and water softeners swap hardness for sodium. A home water test also reports readings that describe the water as a whole, such as pH, total dissolved solids and specific conductance, plus indexes the lab calculates from the other numbers.
These are the readings that make one city's water taste different from another's. Water drawn from the Colorado River, for example, runs very hard.
Minerals and water character: why does it matter?
What minerals cost you is comfort, not health.
Hard water leaves scale in water heaters and on fixtures, and we flag it above 120 mg/L as CaCO3. Sulfate and chloride change the taste at high levels, and sulfate can have a laxative effect; we flag sulfate above 500 mg/L, chloride above 500 mg/L and total dissolved solids above 1,000 mg/L, as comfort items.
Sodium matters if you follow a low-sodium diet, especially if a softener adds more. Corrosion is the one reading that can lead somewhere serious: water that dissolves pipe can pull lead from old solder, which is why the chloride-to-sulfate ratio appears here even though it is only a calculation.
EPA's secondary drinking water standards are non-enforceable guidelines for cosmetic and aesthetic effects, such as taste, odor, color and staining, and for technical effects on pipes and fixtures.
US EPA, Secondary Drinking Water Standards: Guidance for Nuisance Chemicals
California sets its upper secondary levels for sulfate and chloride at 500 mg/L and for total dissolved solids at 1,000 mg/L, in its table of secondary maximum contaminant levels.
USGS describes hardness as a property of water that is not a health concern, though it can be a nuisance.
US Geological Survey, Hardness of Water (Water Science School)
EPA-funded research links a higher chloride-to-sulfate mass ratio in water to faster galvanic corrosion of lead solder, an indirect route for lead into homes with older plumbing.
US EPA Office of Research and Development, chloride-to-sulfate mass ratio and lead solder corrosion
The minerals on a home water test, one by one
Minerals are what your water picked up from the rock and soil it passed through. The ones below shape taste, scale and how the water treats your pipes. Only three carry a comfort line on your report, sulfate, chloride and hardness, and none of them is ever a health flag.
| Substance | Comfort line | Why it matters | The fix |
|---|---|---|---|
| Calcium | None set | An essential nutrient and half of what makes water hard. Limestone, dolomite and gypsum. | A water softener, if the hardness bothers you. |
| Magnesium | None set | An essential nutrient and the other half of what makes water hard. Dolomite and other magnesium-bearing rock. | A water softener, if the hardness bothers you. |
| Hardness Lab reports may say: Total Hardness, Expanded Hardness, Hardness (Calculated), Grains per gallonFull page: Water hardness | 120 mg/L as CaCO3 | Scale on pipes, water heaters and fixtures, soap that will not lather, and spots on glass. Never a health issue. Calcium and magnesium from limestone and dolomite. | A water softener. |
| Sodium | None set | Matters mainly if you follow a low-sodium diet. Water softeners add it. Rock and soil, road salt, water softeners and seawater near the coast. | Reverse osmosis. |
| Potassium | None set | An essential nutrient; no agency sets a drinking-water line for it. Weathering rock and some fertilizer runoff. | Nothing to fix; it is part of your water's character. |
| Sulfate | 500 mg/L | At high levels it can taste bitter and have a laxative effect. Gypsum and other sulfate minerals, plus some industrial discharge. | Reverse osmosis. |
| Chloride | 500 mg/L | At high levels it makes water taste salty. Natural salt deposits, road salt, softener discharge and seawater near the coast. | Reverse osmosis. |
| Bicarbonate Lab reports may say: Bicarbonate (HCO3-) | None set | The main part of your water's alkalinity; it steadies the water against turning acidic. Limestone and other carbonate rock. | Nothing to fix; it is part of your water's character. |
| Carbonate Lab reports may say: Carbonate (CO3 2-) | None set | The smaller part of alkalinity, present when water runs more alkaline. Limestone and other carbonate rock. | Nothing to fix; it is part of your water's character. |
| Alkalinity Lab reports may say: Alkalinity (as CaCO3), Total Alkalinity | None set | How well your water resists swings in pH, mostly from bicarbonate. Carbonate rock like limestone and dolomite. | Nothing to fix; it is part of your water's character. |
| Phosphorus | None set | No agency sets a drinking-water line for the phosphorus a water test reports. Fertilizer runoff, detergents and septic influence; some utilities add phosphate to protect pipes. | Nothing to fix; it is part of your water's character. |
Water character: pH, dissolved solids and corrosion
These readings describe the water as a whole rather than one substance in it. pH and dissolved solids carry comfort lines on your report; the indexes are calculated from the other readings and explain scale or corrosion you may already see.
| Substance | Comfort line | Why it matters | The fix |
|---|---|---|---|
| pH | 6.5 to 8.5 pH | Water outside this range can corrode pipes or leave scale, and taste bitter or soapy. Set by the source water's geology and by treatment; utilities raise pH on purpose to protect pipes. | Corrosive water wears plumbing; replacing damaged pipe and fixtures is the lasting fix. |
| Total dissolved solids Lab reports may say: Total Dissolved Solids, TDS | 1,000 mg/L | The sum of every dissolved mineral; high levels taste salty or bitter and leave scale. Minerals and salts the water picked up from rock and soil. | Reverse osmosis. |
| Specific conductance Lab reports may say: Specific Conductivity, Conductivity | None set | How well the water carries electricity, a quick stand-in for how much is dissolved in it. Rises with dissolved minerals and salts. | Reverse osmosis lowers it along with dissolved solids. |
| Langelier Saturation Index Lab reports may say: LSI | None set | Estimates whether your water leans toward leaving scale or toward dissolving pipe. Calculated from pH, temperature, hardness, alkalinity and dissolved solids. | If corrosion has damaged pipe or fixtures, replacing them is the lasting fix. |
| Chloride-to-sulfate mass ratio Lab reports may say: Chloride-to-Sulfate Mass Ratio, CSMR | None set | A higher ratio is linked to faster corrosion of lead solder, a route for lead into older homes' water. Calculated from the chloride and sulfate readings. | If your home has lead solder, a carbon filter certified for lead guards the kitchen tap. |
| Sodium adsorption ratio Lab reports may say: Sodium Adsorption Ratio, SAR | None set | A measure for irrigation and soil, not for drinking water. Calculated from the sodium, calcium and magnesium readings. | Nothing to fix for drinking water. |
What helps against Minerals and water character?
The approaches below are the ones people use for Minerals and water character at home. Each entry says what it does and what it cannot do, and not every one helps.
Direct fixes
Reverse osmosis at the kitchen tap
Removes dissolved minerals, including sodium, sulfate, chloride and total dissolved solids, from your drinking and cooking water.
Point-of-use only. It does not protect the rest of the house from scale.
Bigger retrofits
Whole-house water softener
Removes the calcium and magnesium that make water hard, protecting the water heater, fixtures and appliances from scale.
Adds sodium in step with the hardness it removes, and does nothing for health. It is a comfort product.
Free and behavioral
Nothing, for most readings
Most minerals on a water test are part of your water's character. Knowing them explains taste and scale; it does not call for a fix.
Common questions about Minerals and water character
Are the minerals in tap water good for you?
Calcium, magnesium and potassium are essential nutrients, and most of what you need comes from food. They are not a health concern at the levels found in tap water. What they change is taste and scale.
Is sodium in tap water a problem?
Only for people on a low-sodium diet, and mostly when a water softener adds it. No agency sets a drinking-water line for sodium. If you soften your water and watch your sodium, keep one unsoftened tap for drinking or use reverse osmosis there.
What does TDS mean on a water test?
Total dissolved solids is the sum of every mineral and salt dissolved in the water. High levels taste salty or bitter and leave scale. California's upper comfort level is 1,000 mg/L, and it is an aesthetic level, not a health limit.
Sources cited for Minerals and water character
Every number on this Minerals and water character page traces to one of the 5 sources below: 5 government or regulatory.
Government & regulatory
- US EPA, Secondary Drinking Water Standards: Guidance for Nuisance Chemicals
- California State Water Resources Control Board, MCLs/DLRs/PHGs table including secondary MCLs (22 CCR 64449)
- US Geological Survey, Hardness of Water (Water Science School)
- US EPA Office of Research and Development, chloride-to-sulfate mass ratio and lead solder corrosion
- US Geological Survey, Corrosivity of groundwater