Which Garden Hoses are Our Safest Bet?
As March turns to April, I’m taking stock of my gardening supplies for the coming season. (Well, I’m thinking about taking stock of my gardening supplies.) We’re getting ready to expand our vegetable garden this year, and I’ve got hoses and drip irrigation on my mind.
When I purchased a new hose a few years ago, a “drinking water safe” label on some hoses caught my eye. Calling those hoses “safe” implies that other hoses are not.
I recalled the interesting flavor of hose water from my childhood—the terroir of a hot summer day, perfectly paired with freezie pops. Turns out, the je ne sais pas in hose water is the taste of toxic volatile compounds. Is nothing sacred?
Image: several eggplant rest in a white crate
Ecology Center’s Garden Hose Study
In 2016, the Ecology Center in Ann Arbor, MI published findings from a study of 32 garden hoses. 24 of the hoses were made of flexible vinyl (PVC), 5 were polyurethane, and one was made of rubber. The other two were different polymers—large molecules that can either be synthetic (like Teflon or polyester) or naturally occurring (like proteins or wool) (Gelfand Center). I assume these polymers were synthetic and petroleum-based. 10 of the 32 hoses were labeled “drinking water safe.”
The Center found that PVC hoses often contained “elevated” lead, bromine, antimony, and phthalates—contaminants that can cause a range of health issues and birth defects. These compounds weren’t found in hoses that didn’t contain PVC. Recycled electronics appear to have been used in many PVC hoses, which helps account for the presence these contaminants.
7 of the 24 PVC hoses contained “at least 100 ppm [parts per million] and as high as 68,000 ppm” lead. To give a point of reference, 90 ppm is the maximum amount of lead permitted in children’s toys by federal regulations. According to the CDC, “No safe blood lead level in children has been identified. Even low levels of lead in blood have been shown to affect a child’s intelligence, ability to pay attention, and academic achievement.”
Phthalates were found in 18 of the PVC hoses, making up 1 to 8% of the weight of the hose. Phthalates have been shown to be endocrine disruptors at very low levels (Steingraber, 113). Half of the PVC hoses contained over 1000 ppm bromine, and over 500 ppm antimony.
This article gives handy charts with US Environmental Protection Agency (EPA) drinking water limits for each chemical. For example, the EPA requires remediating drinking water with lead levels above 0.015 mg/L (15 ppb), and antimony levels above 0.006 mg/L—thousands or millions of times lower than the concentrations in some of the hoses tested. (“mg/L" is about equal to ppm.)
Of course, knowing how much of these contaminants is found in the hose doesn’t tell us how much actually gets into the water. The Ecology Center fills us in on this front, too.
Image description: A patch of purple violets bedazzle a spring day
7 of the hoses were subjected to a water leaching test. Municipal water was left in each hose for 48 hours. 3 were then tested for phthalates, 3 for BPA, and 6 for lead.
According to the Ecology Center, “BPA and lead were found to leach into water held in certain hoses. Phthalates were not detected in the hose water, although similar leaching tests in recent years did find phthalates leaching into the water.”
Three of the water samples contained lead; levels were at 13, 19, and 20 ppb. As noted above, the EPA requires remediation for lead levels above 15 ppb in drinking water. If a hose contained lead, it leached lead. The Ecology Center noted that “The one anomalous result was from the Swan female-female leader hose, which had over 5,000 ppm lead but did not leach lead.”
Do these contaminants migrate from hose water into plants?
This Ecology Center study didn’t test plants watered with the hoses for contaminants. But, other studies have tested plants for uptake of these chemicals. This report shares findings that lead can be taken up by root veggies like carrots, beets, radishes, and turnips, but is less likely to be taken up into a plant's leaves. Because of the large size of a BPA molecule, I’ve generally read that uptake past the roots is unlikely. BPA was found to be mobile in lettuce grown hydroponically (in a water solution without soil). It wasn’t very mobile in hydroponic tomatoes. (This could be an entire article in itself—I’ll stop here for now!)
Image: black cohosh, a native plant used for its medicinal root (best cultivated rather than foraged due to dwindling wild populations)
What about the “drinking water safe” hoses?
I was happy to read that the hoses marketed as “drinking water safe” were found to be “free of significant lead, bromine, antimony, and tin” by the Ecology Center. 3 of the 10 did contain phthalates.
The 2 polyurethane hoses labeled “drinking water safe” turned up none of the contaminants that were tested for. 2 of the 3 polyurethane hoses that weren’t labeled as such contained lead in the brass connectors.
Recommendations for gardeners and buyers
Regardless of what type of hose you have, there are easy habits you can adopt to reduce your garden’s exposure to contaminants:
Flush out water that’s been sitting in the hose before use. Contaminants may be more concentrated in this water.
Storing the hose out of direct sunlight can also reduce the leaching of contaminants into the water (and the deterioration of the hose, in general).
The Ecology Center offers helpful recommendations for folks in the market for a new hose. Here are my main takeaways:
Don’t buy hoses made of PVC if you can avoid it.
Polyurethane or rubber hoses labeled “drinking water safe” are better options. (More about rubber hoses below.) While PVC hose packaging often doesn’t indicate what the hose is made out of, polyurethane hose labels often do.
A “lead-free coupling” label is inadequate, since the rest of the hose may contain lead. A “lead-free” label should apply to the entire hose.
Though the Ecology Center’s study didn’t turn up contaminants of concern in rubber hoses, my understanding is that there’s a difference between hoses made from natural rubber vs. synthetic rubber. The latter are generally made from reused automobile tires.
In this NC Extension article, Lucy Bradley lists a host of contaminants found in tires: “aluminum, cadmium, chromium, copper, iron, magnesium, manganese, molybdenum, selenium, and sulfur, as well as a high level of zinc. They also contain plasticizers and accelerators used during the vulcanizing process. In addition, rubber can also absorb heavy metals like lead.” Since tires weren’t designed with our edible plants in mind, it’s not surprising that a hose made of tires may not be safe for this use. Bradley notes that these contaminants can leach into the soil and enter our garden plants. If I were buying a rubber hose, I’d stick with a natural one.
If you’re feeling overwhelmed by all these garden hose materials and options, Tara Rubin of Lead Free Mama offers a handy tip in her article on lead-free hoses. Marine/RV drinking water delivery hoses are lead-free and food-grade to ensure that the drinking water on boats and RVs is safe. These hoses are typically white and/or blue. They may be a bit pricier than an average garden hose, but this seems like a nice option.
For more details about the Ecology Center’s study, check out the full report here.
Source Not Linked in Article:
Steingraber, Sandra. Living Downstream: An Ecologist’s Personal Investigation of Cancer and the Environment. Da Capo Press, 2010. Pg. 113.
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Image: fresh basil growing in garden pots
