The 300 people in Tonyville, tucked between the beige Sierra foothills and the boundless green of surrounding orchards, also face severe water problems. Senaida Aguilar, a vigorous 71-year-old farmworker, raised three children here after moving in the mid-1980s from her hometown of Morelia, in southern Mexico. Her skin is tanned and creased after nearly 30 years of laboring in the olive and orange orchards.

Thick gloves protect her forearms from thorns, and she wears a heavy canvas fruit-picking apron, with a large, kangaroo-like pouch in front. It takes 18 filled aprons -- over 1,600 pounds of citrus altogether -- to fill a single bin, she explains; she earns $14.50 for each bin.

She is still strong and though she no longer climbs the ladders, Aguilar says she can keep up with most of the younger pickers by working the lower limbs, filling a bin an hour. But the contract work that has become standard today makes her wages unpredictable. "Now they tell you they need a certain number of bins, and they send you home once they are filled." That means that, on many days, it is simply not possible for Aguilar to fill her eight bins.

This strains her budget, which includes $650 a month in rent. She also pays around $50 a month to the Lindsay-Strathmore Irrigation District for water that's undrinkable. So she spends another $50 to $100 a month for five-gallon bottles at water vending machines for drinking and cooking. Aguilar's situation is not unique; seven out of 10 Tulare County households surveyed in 2011 by the Oakland-based Pacific Institute spent close to 5 percent of their annual income on water -- three times the "affordability threshold" set by the EPA.

Aguilar shows me several recent warnings from the irrigation district, one mentioning "disinfection byproducts" -- trihalomethanes and haloacetic acids -- found at concentrations nearly twice the state limit. The warning that follows is confusing at best. One sentence reads, "You DO NOT need to use an alternative (e.g., bottled) water supply." But the following line is hardly reassuring: "Some people who use water containing trihalomethanes in excess of the MCL over many years may experience liver, kidney, or central nervous system problems and may have an increased risk of getting cancer."

The most ominous warning, however, arrived with Aguilar's February bill. It reads, TONYVILLE WATER HAS HIGH LEVELS OF PERCHLORATE. DO NOT DRINK THE WATER OR USE IT TO MAKE INFANT FORMULA. Perchlorate, a potent thyroid inhibitor, is often used in munitions manufacturing but can also be derived from fertilizers.

Aguilar runs a glass from her bathroom tap and brings it into the light. The water has a slightly yellowish tinge and some days looks cloudy, she says, "the color of pond water." It has a faint acrid smell, reminiscent of wet animal fur tinged with lighter fluid.

No one knows the actual toll bad water is taking on human health around here. But residents all share stories of illness or death. Aguilar mentions people who developed strange rashes and sores after using the water for bathing. Another Tonyville resident, Guadalupe Nunez, tells me she knows 11 people who have died of liver, stomach and kidney cancers in Tonyville in less than 10 years.

Public health statistics show the death rates from infant health issues (including birth defects, miscarriage and Sudden Infant Death Syndrome), digestive system cancers and other illnesses associated with nitrate exposure in Tulare County have been above statewide averages at one time or another since 2001. California public health workers found a cluster of childhood cancers in the Tulare County town of Earlimart between 1986 and 1989 -- all the victims were children of farmworkers. Of course, proving a definitive link between water contaminants and disease requires long-term, longitudinal studies -- the sorts of public-health inquiries that are rarely made in these virtually invisible communities.

To learn more about what water managers are doing to fix Tonyville's problems, I call Scott Edwards, Lindsay-Strathmore's district manager, whose name and number are listed on the warning notice. Edwards explains that most of the time Tonyville's water comes through surface canals, but that the perchlorate spikes occur every year or two when the canal is "dewatered" and the town switches from canal water to groundwater.

According to Edwards, Tonyville's filtration plant is simply incapable of removing the perchlorate from its groundwater. (He admits he doesn't know where the perchlorate is coming from.) "State and federal regulations say we must deliver clean drinking water, even though we can't afford to do that," he says, explaining that treatment costs already run from $1,500 to $2,000 an acre-foot, while residents are paying only $250 per acre-foot. "Tonyville residents would be paying $450 a month to operate that plant. What am I supposed to do, raise the rates? They can't afford that."

But clean drinking water is a human right in California, I point out, referring to the new bill's wording. "Drinking water is not a human right. Get that off your head right now," says Edwards. "If it costs somebody else money to provide it to you, it's not your right."

He quickly shifts to a more sympathetic tone, though, noting that he lives in an unincorporated part of Tulare County and his water, too, is unfiltered and undrinkable. "We have bottled water in our house at all times."

As a manager tasked with delivering high-quality water across the county, does he find this fact troubling or, at the very least, somewhat ironic? "It is what it is," he replies.