The Water Gap and How We Move Forward

Feasibility Over Health: How the System Works

Public drinking water in the U.S. is regulated under the Safe Drinking Water Act (SDWA), passed in 1974. For decades, its core standards have seen only incremental change.

The last major contaminant updates came more than twenty years ago: disinfection byproducts in 1998, radionuclides in 2000, and arsenic in 2001. In 2024, the Environmental Protection Agency (EPA) announced the first national drinking water standards for PFAS (“forever chemicals”), a long-overdue move. But by 2025, much of that rule was rolled back and the compliance deadline was pushed to 2031 (EPA PFAS Rule Summary, 2024).

So we’re left with a framework built for the contaminants of the past, trying to manage the chemistry of today.

Here’s how that framework works:

• The EPA first defines a health-based goal, called a Maximum Contaminant Level Goal (MCLG). This represents the level below which “no known or anticipated adverse effect on the health of persons would occur, and which allows an adequate margin of safety.” (EPA, Chemical Contaminant Rules).
• The MCLG is calculated using standard assumptions: a 70-kilogram adult drinking 2 liters of water per day over a 70-year lifetime. Adjustments are added for sensitive populations (typically a tenfold safety factor for infants, children, and pregnant women). (EPA Drinking Water Standards Table, 2018)
• After the MCLG is set, the EPA establishes the enforceable standard, the Maximum Contaminant Level (MCL), “as close to the MCLG as feasible,” considering cost and available treatment technology.

That word – feasible – defines everything. It means the number you see on your water report isn’t necessarily what’s safest. It’s what’s achievable at scale.

Take arsenic. The EPA’s health-based goal (MCLG) is zero and the EWG defined limit is 0.004 parts per billion. The enforceable limit (MCL) is 10 parts per billion (EPA, Arsenic Rule Technical Summary).

That’s 2,500 times higher than the health-based target. The difference isn’t scientific, it’s logistical. It’s the space between what’s ideal and what’s practical for utilities to meet.

That’s the water gap.

How did we get here?

The U.S. has about 55,000 community water systems, and roughly 90% serve fewer than 5,000 people. (EPA Safe Drinking Water Information System)

These small systems are often underfunded, under-resourced, and reliant on aging infrastructure. Testing for hundreds of potential contaminants simply isn’t realistic. As a result, monitoring follows a “feasibility cadence”:

• Microbes tested monthly
• Disinfection byproducts quarterly
• Chemical contaminants annually or every few years
• Radiologicals once every four years

It’s a schedule designed for manageability, not comprehensive safety. And if problems arise from the testing, the brittleness and fragmented nature of the systems makes it hard to deal with. Remember Flint?

In 2014, the city switched its water source from Lake Huron (via Detroit’s system) to the Flint River to save money. On paper, it was a “feasible” decision, financially and operationally. But feasibility can’t fix chemistry. The Flint River’s water was more corrosive than the infrastructure was built to handle. Normally, utilities add corrosion-control chemicals to keep pipes from leaching lead. Flint didn’t.

Within weeks, residents complained about brown, foul-smelling water. The city maintained it was safe because early testing technically met federal standards. Under the EPA’s Lead and Copper Rule, utilities can average results across samples, masking extreme outliers.

By the time independent researchers from Virginia Tech tested the water, lead levels in some homes exceeded 13,000 parts per billion. The EPA’s action level is 15.

The system had done exactly what it was designed to do: comply with a feasibility-based framework. And that framework failed in real time. Even after national attention, replacing Flint’s lead service lines took years and cost hundreds of millions of dollars. For residents, the harm was immediate and irreversible.

Flint wasn’t an anomaly, it was a warning. The same logic that governs water limits governs treatment response. The moment contamination occurs, the feasibility model collapses. Small systems can’t afford advanced treatment. Large systems can’t overhaul infrastructure quickly enough. Regulatory action moves slower than damage.

That’s the part of the water gap we rarely talk about. It’s not just about limits on paper, it’s about what happens when the system hits those limits in the real world.

So what about bottled water?

While it’s regulated by the Food and Drug Administration (FDA) rather than the EPA, the underlying framework is similar. When the EPA establishes a new MCL, the FDA can either adopt the same threshold or justify why no standard is needed (FDA Bottled Water Standards Overview).

But FDA enforcement is weaker:

• Testing is less frequent: weekly for microbes, annually for chemicals, every four years for radiologicals.
• There are still no federal standards for PFAS or microplastics in bottled water. (EPA PFAS Drinking Water Q&A, 2024)

In short, bottled water often adheres to the same feasibility-based limits as tap water, sometimes with less oversight.

Why “Feasible” Isn’t the Same as “Safe”

When you start reading water reports, the numbers look precise and reassuring. But most are built on compromise.

Take arsenic again. The EPA’s goal is zero. The legal standard is 10 parts per billion. The Environmental Working Group’s (EWG) guideline? 0.004 parts per billion.

That gap isn’t theoretical, it’s lived.

We’ve accepted “good enough” as safe. That’s a strange logic for something that makes up 60% of our bodies and 75% of our babies’. Safe, under this framework, doesn’t mean no risk. It means manageable risk, defined by what we can afford to fix.

It’s a trade-off most people never consented to, yet one we live with every time we turn on the tap.

The Way Forward

This isn’t about panic. It’s about perspective. Our water systems weren’t designed for PFAS, microplastics, pharmaceuticals, or industrial runoff that migrates through soil and air. They were designed for a smaller world, with fewer chemicals and fewer people.

We can’t retrofit that with wishful thinking. If the system that delivers our most essential resource is built for feasibility, not health, then it’s time to start closing the gap ourselves.

Transparency, independent testing, and modernized standards shouldn’t be niche, they should be the norm. Because when we know what’s in our water, we can decide what should be.

References

1. U.S. Environmental Protection Agency, “Background on the Safe Drinking Water Act” (PDF)
2. EPA, “Chemical Contaminant Rules”
3. EPA, “Drinking Water Standards and Health Advisories Table,” 2018
4. EPA, “Arsenic Rule Technical Summary”
5. EPA, “PFAS National Primary Drinking Water Regulation” (2024 Q&A)
6. FDA, “Bottled Water Standards and PFAS Testing”
7. EPA Safe Drinking Water Information System