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Fruit juices and soft drinks are acidic, and will tend to corrode and dissolve whatever metals they come in contact with - e.g. the pipes and valves and contain

Fruit juices and soft drinks are acidic, and will tend to corrode and dissolve whatever metals they come in contact with - e.g. the pipes and valves and containers. This produces a bunch of metal ions, will end up dissolved in the liquid. Along similar lines, acidity (well, really not enough alkalinity) was a big factor in the municipal water problems at Flint, Michigan: the water in the pipes was allowed to become too acidic, causing it to react with the lead pipes - significantly increasing the amount of lead dissolved in the water. Whereas if the water had been more alkaline (higher pH), the lead in the pipes would not have ended up in the water to nearly the same extent.

Scoundreller 4y ago
pH control is one method of stabilizing lead, orthophosphate is another (which Flint didn’t bother with). > Most important, the treated Flint River water lacked one chemical that the treated Detroit water had: phosphate. “They essentially lost something that was protecting them against high lead concentrations,” Giammar says. Cities such as Detroit add orthophosphate to their water as part of their corrosion control plans because the compound encourages the formation of lead phosphates, which are largely insoluble and can add to the pipes’ passivation layer. … > The treated Flint River water had a relatively low pH that decreased over time. According to monthly operating reports from the Flint treatment plant, the city’s water had a pH of about 8 in December 2014, but then it slowly dropped to 7.3 by August 2015. Environmental engineers say that if water pH drifts too low in the absence of orthophosphate, the water can start to leach high levels of lead from pipes. > The pH drop over time seems to indicate that plant operators in Flint didn’t even have a target pH as part of a corrosion plan, Edwards says. Water utilities usually find a pH that’s optimal for preventing corrosion in their system. For example, in Boston, another city with old lead pipes, average water pH held steady around 9.6 https://cen.acs.org/articles/94/i7/Lead-Ended-Flints-Tap-Water.html https://cen.acs.org/articles/94/i7/Lead-Ended-Flints-Tap-Wat...
- HPsquared 4y ago
  pH is the fundamental thing, phosphate is the chemical patch that allows low pH water to be used. Basically they switched water source to something less alkaline than what they'd used previously - and didn't do anything to mitigate this. The phosphate is kind of a "patch" to the problem of low pH. Fruit juice and cola is of course much, much more acidic than the Flint water - orange juice for example is about pH 4 (that is, 1000 times more H+ ions than pH 7)

Scoundreller 4y ago

pH control is one method of stabilizing lead, orthophosphate is another (which Flint didn’t bother with). > Most important, the treated Flint River water lacked one chemical that the treated Detroit water had: phosphate. “They essentially lost something that was protecting them against high lead concentrations,” Giammar says. Cities such as Detroit add orthophosphate to their water as part of their corrosion control plans because the compound encourages the formation of lead phosphates, which are largely insoluble and can add to the pipes’ passivation layer. … > The treated Flint River water had a relatively low pH that decreased over time. According to monthly operating reports from the Flint treatment plant, the city’s water had a pH of about 8 in December 2014, but then it slowly dropped to 7.3 by August 2015. Environmental engineers say that if water pH drifts too low in the absence of orthophosphate, the water can start to leach high levels of lead from pipes. > The pH drop over time seems to indicate that plant operators in Flint didn’t even have a target pH as part of a corrosion plan, Edwards says. Water utilities usually find a pH that’s optimal for preventing corrosion in their system. For example, in Boston, another city with old lead pipes, average water pH held steady around 9.6 https://cen.acs.org/articles/94/i7/Lead-Ended-Flints-Tap-Water.html https://cen.acs.org/articles/94/i7/Lead-Ended-Flints-Tap-Wat...

HPsquared 4y ago
pH is the fundamental thing, phosphate is the chemical patch that allows low pH water to be used. Basically they switched water source to something less alkaline than what they'd used previously - and didn't do anything to mitigate this. The phosphate is kind of a "patch" to the problem of low pH. Fruit juice and cola is of course much, much more acidic than the Flint water - orange juice for example is about pH 4 (that is, 1000 times more H+ ions than pH 7)