4-Androstene-3,17-dione in Drinking Water: Complete Guide (2026)

What is 4-Androstene-3,17-dione and Why Does It Matter?

# 4-Androstene-3,17-Dione in Tap Water: What You Need to Know

## What It Is and Where It Comes From

4-Androstene-3,17-dione, commonly called androstenedione or "andro," is a hormone precursor that your body naturally produces in small amounts. It's also sold as a dietary supplement and banned by many sports organizations because it converts to testosterone. When people take supplements or use certain personal care products, their bodies excrete this compound into wastewater. Municipal water treatment plants weren't designed to remove hormones, so androstenedione passes through and ends up in tap water. Our data shows it's been detected in 310 water systems across the United States, with concentrations averaging 0.125 parts per trillion (ppt) and peaking at 1.12 ppt.

The presence of this chemical in drinking water reveals a growing problem: emerging contaminants from modern life. Unlike regulated pollutants from industrial sources, androstenedione comes from thousands of individual choices—supplement use, prescription medications, and personal care products. When wastewater treatment plants can't remove these compounds, they enter rivers and groundwater that supply drinking water. This is especially common in areas with aging water infrastructure or high supplement use among certain populations.

## Health Effects and Risk Assessment

The health effects of low-dose androstenedione exposure through drinking water remain poorly understood. At the levels detected in tap water (less than 1.5 ppt), direct hormonal effects are considered minimal by most toxicologists. However, this doesn't mean there's no reason for concern. Androstenedione is an endocrine disruptor, meaning it can interfere with your body's hormone system even at very low doses. This is particularly important for children, whose developing reproductive and nervous systems are more sensitive to hormonal disruption.

Studies on animals show that continuous exposure to hormone-like compounds can affect sexual development, fertility, and metabolism. Human studies are limited, partly because it's difficult to isolate the effects of one contaminant when people are exposed to dozens simultaneously. The EPA hasn't established a drinking water standard for androstenedione, which means there's no legal limit. This gap in regulation doesn't indicate safety—it reflects the fact that water quality standards lag behind emerging science.

## Regulation and Current Guidelines

Currently, androstenedione has no EPA maximum contaminant level (MCL) for drinking water. The EPA focuses its standards on contaminants with strong evidence of harm at specific doses, and research on androstenedione at drinking water levels is still developing. The Environmental Working Group (EWG) hasn't published a specific health guideline for this compound either, partly because the science is evolving.

This regulatory gap is frustrating for homeowners who want clear answers. The absence of a standard doesn't mean your water is safe—it means the government hasn't formally assessed this particular chemical yet. What we do know is that androstenedione shouldn't be in drinking water at all. The presence of any hormone precursor indicates that wastewater treatment needs improvement, and it suggests your water may contain other unregulated contaminants.

## Geographic Patterns and Why They Matter

Illinois leads the nation with androstenedione detected in 85 water systems, followed by Colorado (32), Washington (29), Iowa (27), and Montana (23). This geographic clustering tells a story. Illinois's high numbers likely reflect both population density and wastewater treatment challenges in aging infrastructure around Chicago and other cities. Colorado and Washington's detections may correlate with higher supplement use in health-conscious communities and mountain regions where groundwater is vulnerable.

The concentration data is reassuring in one way: no water system exceeded any health guideline. However, the maximum detection of 1.12 ppt in some systems shows that androstenedione is genuinely present, not just a trace artifact. If you live in Illinois, Colorado, Washington, Iowa, or Montana, your water system is more likely to contain this contaminant.

## Removal Methods and What You Can Do

Advanced filtration removes androstenedione effectively. Reverse osmosis systems eliminate 95-99% of hormone-like compounds, making them your best option for comprehensive protection. Activated carbon filters also work, though effectiveness varies by filter quality and contact time. If your water system is among the 310 affected, installing a reverse osmosis system under your sink or a whole-home filtration system provides reliable protection for your family's drinking and cooking water.

Request your local water quality report to see if androstenedione has been detected in your area. If it has, filtration is a smart investment—not because current levels are acutely dangerous, but because removing unregulated contaminants is a reasonable precaution for your family's long-term health.

Regulatory Standards for 4-Androstene-3,17-dione

Cities With the Highest 4-Androstene-3,17-dione Levels

States Most Affected by 4-Androstene-3,17-dione

Frequently Asked Questions

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