Arsenic in Connecticut Wells Near Old Orchards: What UConn Found and How to Check Your Land

Connecticut's old fruit orchards may still be showing up in its wells. Lead arsenate pesticides were widely used on fruit trees from the 1890s to the 1950s, and the state had more than 47,000 orchards in 1935. Researchers at UConn and Eastern Connecticut State University found that wells containing arsenic tended to sit closer to those historic orchards than wells without it (Higgins, Metcalf and Robbins, Journal of Environmental Quality, 2021).

Many of those orchards are now subdivisions. Nobody selling you the house is likely to mention it.

What Did the Connecticut Orchard Study Actually Find?

Arsenic was more likely where orchards had been. The study found that wells with no detected arsenic were farther from historic orchards and had fewer of them nearby, while the wells closest to impacted soils tended to have the highest arsenic (Higgins et al., 2021).

Three findings stand out:

• The residue is still there. Elevated arsenic and lead were widespread in soils from orchards established by 1951, with some arsenic concentrations above 200 ppm.
• Some of it can move. In synthetic rain tests in the lab, arsenic and lead in some soils leached at concentrations above EPA drinking water standards.
• Forested land looked different. Wells in areas that were forested before 1970 contained no arsenic.

The work began with a 2013 request from CT DEEP to survey wells for arsenic in eastern Connecticut, starting in Lebanon (UConn Today, 2021). So the fieldwork leans east. The authors say historic orchard soils deserve more attention as a possible contributing source statewide, where well contamination rates are high.

Does This Prove the Orchards Poisoned the Wells?

No, and the researchers say so. They describe a strong spatial relationship, which isn't the same as a traced pathway. Mark Higgins told UConn Today that the arsenic in soil cores was probably immobile and unlikely to still be moving downward, while recent studies suggest phosphate fertilizers can mobilize contaminants that had been locked in place (UConn Today, 2021).

Geology complicates it further. Elsewhere in the state, wells sit near both old orchards and arsenic-rich rock, so sorting one source from the other takes more evidence. Our guide to arsenic and uranium in Connecticut wells by region covers the bedrock side.

For a homeowner, the source matters less than the result. Whether arsenic came from a 1930s spray rig or from the rock, it looks the same on a lab report, and it's treated the same way.

The EPA's own limits table lists "runoff from orchards" alongside natural deposits as a source of arsenic in drinking water (EPA). This isn't a fringe idea.

How Do I Check Whether My Land Was an Orchard?

Connecticut has an unusually good record of this. In 1934 the state commissioned Fairchild Aerial Surveys to photograph the whole state from the air, one of the earliest statewide aerial surveys in the country (CT ECO).

Here's how to use it:

1. Open the 1934 aerial photos at CT ECO and find your property, or use UConn's side-by-side 1934 comparison map.
2. Look for trees in tight, evenly spaced rows. Orchards read as a regular grid, unlike the random texture of woodland.
3. Check your neighbors too. CT DPH's flag is a well within a quarter mile, not just on your lot.

There's a limit worth knowing. The study's soil findings cover orchards established by 1951, so a tree-free 1934 photo doesn't clear a parcel planted in the 1940s. UConn reports that one redeveloped orchard site without contaminated soil had trees that weren't planted until around 1970, after these pesticides fell out of style (UConn Today, 2021). Timing matters as much as location.

Weston is one town where this question has reached the research record. A 2024 Geological Society of America conference abstract is titled "An Investigation of Arsenic Groundwater Contamination From Historic Use of Lead Arsenate in Weston, Connecticut". We could confirm only the title, so we aren't reporting its findings. See our Weston well water guide for what the public record shows.

What Should I Test For, and What Does a Result Mean?

CT DPH's troubleshooting table says a well within a quarter mile of a current or former orchard or farmland should be tested for nitrates, arsenic and pesticides, and suggests asking about EPA Method 505 (CT DPH, updated May 2026). Use a laboratory certified by CT DPH.

The number to compare against is 10 micrograms per liter. That's the CT DPH Action Level for arsenic and the same value as the federal limit of 0.010 mg/L for public water (CT DPH). If your well was drilled before October 1, 2022, arsenic testing may never have been required. CT DPH recommends testing at least once for every well, ideally every five years.

Why bother if the water looks and tastes fine? Higgins put the risk plainly: this kind of arsenic is "not something that will make you sick tomorrow or in 10 years," but decades of low-level exposure to a known carcinogen likely carry risk (UConn Today, 2021).

Connecticut wells are worth checking for plenty of reasons beyond orchards. In a UConn Extension program, half of 267 tested wells had at least one contaminant over an EPA maximum contaminant level (Janis, Dietz and Metcalf, 2025). Those were volunteers who signed up for testing, not a random sample. UConn says the most common problem was coliform bacteria (UConn Today, 2024).

The study also measured lead in orchard soils. If you garden on former orchard land, soil is a separate question from your water, so ask your local health department where to start.

Keep Reading

• Private well testing in Connecticut: the complete guide
• Arsenic and uranium in Connecticut wells, by region
• Why a mortgage water test is not enough
• Road salt in Connecticut well water

Sources: Higgins, Metcalf and Robbins, Journal of Environmental Quality (2021); UConn Today (2021); CT DPH testing recommendations (updated May 2026); CT DPH, Arsenic in private well water; EPA National Primary Drinking Water Regulations; CT ECO 1934 aerial photos; UConn MAGIC 1934 comparison map; Janis, Dietz and Metcalf, Journal of Human Sciences and Extension (2025).

About this guide: CheckYourTap is an independent water-quality service funded by Valiant Energy Solutions, a Connecticut water quality and energy services company established in 1930. Valiant offers paid well testing and treatment, which is what the request button on this page connects you with. You can also contact any CT DPH-certified laboratory directly. The facts on this page come from the public sources cited above. For the journal study we read the published abstract and UConn's report of it, not the paywalled full text.