Water Knowledge

Conductivity

Summary: Conductivity (often written as EC) tells you how well water conducts electricity, which depends on the amount of dissolved ions (salts and minerals). Higher EC usually means more total dissolved minerals. EC doesn’t name the ions—so it’s best used as a quick trend check alongside lab tests like chloride, sulfate, hardness, alkalinity, and TDS.

Why homeowners should care

EC is a fast way to see if your water chemistry is changing. Rising EC can hint at increasing salinity (road salt, coastal intrusion), mineral buildup that causes scale, or mixing of different sources. After installing treatment (RO, softening), EC helps confirm performance at a glance.

What conductivity really means

  • Units: typically microsiemens per centimeter (µS/cm). Some meters also show millisiemens (mS/cm).
  • Relationship to TDS: TDS meters often estimate “ppm” from EC using a conversion factor. It’s an estimate—not a list of specific contaminants.
  • What drives EC: Dissolved ions like calcium, magnesium, sodium, chloride, sulfate, bicarbonate. Temperature also affects readings (most meters auto-compensate).

Where higher EC can come from

  • Natural minerals: Groundwater dissolving salts from rock/soil.
  • Road salt or coastal influence: Chloride and sodium can raise EC seasonally.
  • Blending and seasonal shifts: Utilities or wells that switch sources can change EC.
  • Water treatment: Softening doesn’t lower EC much; RO typically lowers EC at the drinking tap.

When to test

  • When setting a baseline for a new home or well.
  • Seasonally in areas affected by road salt, drought, or coastal intrusion.
  • Before and after installing RO or other treatment to verify performance.
  • Any time taste becomes salty/flat or scaling worsens.

How we test

HealthWaterLab measures conductivity with a calibrated four-ring probe and reports EC alongside related parameters when helpful. For troubleshooting, we can pair EC with chloride, sulfate, hardness, alkalinity, and TDS to interpret trends.

How to collect a good sample (or field reading)

  • Use the kitchen cold-water tap (primary drinking tap).
  • Run water a minute or two to bring in fresh water from the line (unless you’re intentionally testing first-draw).
  • Rinse the probe with sample water; avoid air bubbles on the sensors; wait for temperature stabilization.
  • Note the location, date/time, and whether treatment (softener/RO) is upstream of the tap.

How to read your result

  • Low to moderate EC: Typical for many groundwater sources; taste is usually fine.
  • Rising EC over time: Track chloride/sodium and TDS; look for seasonal road-salt effects or source mixing.
  • High EC: Taste can be salty/flat and scale risk rises with hardness. Consider point-of-use RO for drinking water and manage scale in appliances.

Practical homeowner steps

  • Trend it: Log EC with temperature and simple notes (weather, road salt season, treatment changes).
  • Confirm specifics: If EC climbs, test chloride, sodium, sulfate, hardness, and alkalinity to see which ions are driving the change.
  • Protect taste & appliances: Use RO at the kitchen tap for drinking/cooking if EC/TDS is high; use softening and maintenance to control scale.
  • Plumbing awareness: Long stagnation can slightly change EC at the faucet; compare first-draw vs flushed if needed.

FAQ

Is a TDS meter the same as a conductivity meter?

Many “TDS” pens are EC meters that convert EC to ppm using a factor. It’s useful for trends, but it doesn’t identify specific ions.

What EC number is “good” for drinking water?

There isn’t a single “good” EC—acceptable levels vary by region and taste. Use EC to track changes and pair it with lab tests to understand the ions behind the number.

Why didn’t my softener lower EC?

Softeners swap calcium/magnesium for sodium or potassium—total ions change little, so EC stays similar. Softening reduces scale, but RO is what lowers EC/TDS at a drinking tap.

My EC jumped in winter—why?

Road salt runoff can raise chloride and sodium seasonally, especially in shallow wells or areas with permeable soils.

Does high EC mean my water is unsafe?

Not by itself. EC is an indicator of total ions, not a safety test. If EC changes suddenly, run targeted lab tests (chloride, sodium, sulfate) and check taste/odor.

Will a carbon filter reduce EC?

No. Carbon improves taste/odor (e.g., chlorine) but doesn’t remove dissolved ions. RO or distillation lowers EC; softening reduces scale but not EC much.

Why do my RO readings show very low EC?

RO removes many dissolved ions, so EC drops substantially at the RO faucet. Slight rises over time can indicate filters or the membrane need service.

Do temperature and pH affect EC?

Yes. EC increases with temperature; most meters correct for this automatically. pH doesn’t directly set EC but relates to which ions are present.

Should I track EC or TDS for aquariums/coffee/ice?

Either can work for consistency. Many hobbyists use EC/TDS to keep recipes repeatable and to monitor RO/DI performance.

How often should I check EC?

Seasonally for wells prone to salinity shifts, monthly during troubleshooting, and before/after installing or servicing RO/softening.

Want help interpreting EC changes? See testing kits and step-by-step guidance at HealthWaterLab.com.