The 5 Things Lurking in Your Water That You Can’t See, Smell, or Taste

Most of the water quality problems that homeowners notice — the pool-like taste, the rotten egg smell, the white residue on dishes — are the ones caused by things your senses can detect. Those are real issues, and ones that Aqua Clear Water Solutions helps families across McAllen and the Rio Grande Valley address every day.

But sensing a problem is only half the picture. Some of the more concerning contaminants in drinking water do not announce themselves. They have no color, no smell, and no taste that would alert you to their presence. They do not make your water look cloudy or leave rings around your faucet. They simply move through your tap, undetected, until a water test tells a different story.

That is why testing matters as much as observation. At Aqua Clear, we have seen firsthand how often the contaminants that concern families most are the ones they never would have suspected without a closer look. Here are five that show up in testing data relevant to the Rio Grande Valley — and what you can do about them.

1. Arsenic

Arsenic is a naturally occurring element found in rocks and soil throughout the Southwest and South Texas. It dissolves into surface water and groundwater as part of the natural geological cycle, which means it can be present in source water even in areas with no industrial contamination.

According to testing data compiled by the Environmental Working Group from McAllen Public Utility results, arsenic was detected in McAllen tap water at levels above EWG’s health guideline, though below the federal legal limit. The federal MCL for arsenic is 10 parts per billion — a threshold that has not been updated in over two decades and that some public health researchers argue does not fully account for long-term cumulative exposure risk.

Arsenic has no taste at the concentrations found in drinking water. The primary effective treatment option for arsenic in drinking water is reverse osmosis filtration.

2. Disinfectant Byproducts

When municipalities use disinfectants like chlorine or chloramine to treat drinking water — as essentially all municipal systems do — those disinfectants react with naturally occurring organic matter in the source water. The result is a group of compounds called disinfection byproducts, which include trihalomethanes and haloacetic acids.

Testing data for McAllen shows total trihalomethanes and multiple individual haloacetic acid compounds were detected above EWG’s health guidelines, though within federal legal limits. These compounds form as a necessary consequence of treating water to make it microbiologically safe — which is the right priority for a public water system — but they are worth reducing at the point of consumption for households that want a higher standard for their drinking water.

Neither trihalomethanes nor haloacetic acids have a distinctive taste at the levels typically found in treated municipal water. Carbon filtration and reverse osmosis can both reduce these compounds, with RO providing more comprehensive reduction.

Testing data for McAllen shows uranium was detected above EWG’s health guideline, though below the federal legal limit. As with arsenic, uranium is colorless, odorless, and tasteless at the concentrations found in treated municipal water. Reverse osmosis reduces uranium in drinking water.

5. Chlorate

Chlorate is a disinfection byproduct that forms when chlorine dioxide is used in water treatment. It is also present in some agricultural contexts as a component of certain herbicides. McAllen testing data shows chlorate was detected above EWG’s health guideline, with no federal legal limit currently in place for this compound.

Chlorate has been associated with effects on thyroid function, which makes it of particular concern for pregnant women and children. It is a compound that does not have a distinctive taste at typical drinking water concentrations.