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Comment by a3n | Hacker News Reader

> Through continued demonstrations by Flint residents and mounting scientific evidence of the water’s toxins, city and state officials offered various solutions — from asking residents to boil their water to providing them with water filters — in an attempt to work around the need to reconnect to the Detroit system.

Can you boil lead out of water, or does it just become more concentrated?

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Distillation would essentially be doing the reverse, "boiling the water out of the lead", and that would work. But no amount of boiling in a open pot is going to remove lead from your water.

It's hard to tell from the article, but the reference to boiling water might have been in response to the other issue mentioned, trihalomethanes in the water. As dissolved gases, boiling should help drive them out.

(side note: a trihalomethane is more commonly referred to as a haloform, which is the family chloroform comes from)

Yup. Distillation should remove any heavy metal elements. It's not ideal to consume long term, as it removes most useful minerals and results in a hydrogen-heavy/acidic water, but it's certainly far better than consuming lead.

Can you explain what hydrogen-heavy means?

The ratio of hydrogen to hydroxide is higher than it normally is. Water naturally dissociates into hydrogen and hydroxide ever so slightly in equal amounts under neutral conditions.

The auto-dissociation constant Kw is 10^-14 mol^2 L^-2.

That means that concentration of hydronium [H3O+] ion multiplied by the concentration of hydroxide [OH-] ion is equal to the constant. In pure water, there are no other ions to change the balance, so you get 2 H2O <-> H3O+ + OH-, and each concentration is the square root of the dissociation constant.

So 10^-7 mol/L H3O+ and 10^-7 mol/L OH-. The abbreviation "pH" stands for "power hydrogen", and is the negative log10 of the H3O+ concentration. 10^-7 mol/L H3O+ is pH 7, which is neutral. There is also a lesser-known term pOH, which is pretty much pOH + pH = 14 under normal conditions.

But that water doesn't stay perfectly neutral for long. CO2 from the atmosphere dissolves into it, using

  CO2(g) <-> CO2(aq)                           K_CO2 = 2.0e-3, P_CO2 = 3.6e-4
  CO2(aq) + H2O(l) <-> H2CO3(aq)               K     = 1.3e-3
  H2CO3(aq) + H2O(l) <-> H3O+(aq) + HCO3-(aq)  Ka1   = 2.0e-4
  HCO3-(aq) + H2O(l) <-> H3O+(aq) + CO3--(aq)  Ka2   = 4.7e-11

Solving the equilibrium gives you a pH of 5.65 (10^-5.65 mol/L H3O+).

Some natural groundwater contains other dissolved minerals, including carbonates (limestone is CaCO3), which pushes the CO2 equilibrium in the other direction, making water more basic (higher pH).

When you say that boiling results in acidic water, are you referring to the fact that pH-neutral water would be slightly more acidic than your (slightly basic) blood, or is this about dissolved CO2 or something else entirely?

It's due to absorbing C02 from the air whilst in gaseous form, which is then subsequently absorbed into the blood stream after consumption.

@shabda Hydrogen heavy water means acidic water with high amounts of dissolved H+.

> hydrogen-heavy/acidic water, but it's certainly far better than consuming lead.

Yeah, but why would a water with slightly acidic pH be a major problem for health anyway? Numerous mineral waters sold on the market at not at pH 7 in the first place.

Tooth Decay

Well, at least we have solutions to that, unlike young-child lead poisoning.

Dimercaptosuccinic acid is a chelation agent that has been recommended for lead poisoning in children. The side effects seem less severe than most of the effects of lead poisoning.

Definitely would prefer the tooth decay if we have to pick.

No, according to the CDC:

> Heating or boiling your water will not remove lead. Because some of the water evaporates during the boiling process, the lead concentration of the water can actually increase slightly as the water is boiled.

http://www.cdc.gov/healthywater/drinking/private/wells/disea...

It depends on the lead salt type, but you could usually precipitate the soluble lead into an insoluble salt with simple ingredients available at home - then, you could remove the formed salt with a proper filter to remove most of the lead.

http://www.chemguide.co.uk/inorganic/group4/lead.html

Solid guide, but having to purify the water coming out of your tap defeats much of the purpose of having a city water supply.

I agree, but it's usually less expensive than buying bottled water.

You can't boil lead out of water, in the same way that you can't boil salt out of water. Metal extraction is a pretty hard problem.

It seems that you can reduce the levels of the aforementioned trihalomethane compounds by boiling though.

http://dx.doi.org/10.1155/2013/959480

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