The Limitations of Boiling Water for Chemical Removal
Many people assume that because boiling water can kill biological contaminants like bacteria and viruses, it can also destroy or remove chemicals. However, from a scientific standpoint, this is incorrect. Boiling is a physical process, a phase change from liquid to gas, that does not alter the chemical composition of dissolved substances. In fact, for many chemicals, boiling can make the water more dangerous.
Why Chemicals Are Left Behind
Chemicals, minerals, and other dissolved solids have much higher boiling points than water. As the water boils and turns into steam, the non-volatile substances are left behind. This process effectively reduces the volume of water while concentrating the remaining impurities. For instance, if you boil water containing lead, the lead concentration in the remaining water will increase, potentially to harmful levels.
A Deeper Look at Contaminants
Different types of contaminants react differently to the boiling process:
- Volatile Organic Compounds (VOCs): Chemicals like benzene or trichloroethylene (TCE) are volatile and can evaporate with the steam. However, this is not a recommended removal method. Inhaling these airborne chemicals can be a health hazard, and the process is not guaranteed to remove all of them. Oregon.gov and other health agencies advise against boiling chemically contaminated water for this reason.
- Heavy Metals: Substances such as lead, arsenic, and mercury are non-volatile. They do not evaporate and their concentration increases as water volume decreases.
- Nitrates and Fluoride: These chemicals are also highly stable and remain dissolved in the water after boiling. The concentration of both can increase.
- Pesticides and Pharmaceuticals: Many modern pesticides, pharmaceuticals, and 'forever chemicals' (PFAS) are heat-resistant and will not be removed by boiling.
The Correct Use of Boiling
Boiling water is a powerful tool for killing pathogenic microorganisms like E. coli, Giardia, and Cryptosporidium. This makes it an ideal emergency measure for treating water that is suspected of biological contamination, such as during a boil water advisory. The World Health Organization (WHO) and the CDC recommend bringing water to a rolling boil for at least one minute to ensure biological safety.
Comparison of Water Purification Methods
To illustrate the differences, here is a comparison table of boiling versus more comprehensive purification methods.
| Feature | Boiling Water | Water Filtration (e.g., Activated Carbon) | Reverse Osmosis | Distillation |
|---|---|---|---|---|
| Removes Biological Pathogens | Yes (Effective for bacteria, viruses, parasites) | No (Most filters, requires special membranes) | Yes (Removes a wide range) | Yes (Effective) |
| Removes Heavy Metals | No (Concentrates them) | Limited (Some are removed) | Yes (Highly effective) | Yes (Highly effective) |
| Removes Fluoride | No (Concentrates it) | No (Requires specific filters) | Yes (Up to 90%) | Yes (Effective) |
| Removes VOCs | Partially (Evaporates into air) | Yes (Activated carbon is effective) | Yes (Effective) | Yes (Highly effective) |
| Removes Sediments/Particles | No (Requires pre-filtering) | Yes (Effectively removes) | Yes (Effective) | Yes (Effectively removes) |
| Energy/Time Intensive | Yes (Time and energy for heating/cooling) | No (Convenient, on-demand) | Yes (Uses energy for pressure pump) | Yes (Time and energy intensive) |
Conclusion
While boiling is a simple and effective method for killing harmful pathogens, it is critically important to understand that it is not a cure-all for water contamination. Does boiling water get rid of chemicals in it? No. In fact, for many chemical contaminants, the process only makes the situation worse by increasing their concentration. To ensure complete protection from both biological and chemical impurities, boiling should be combined with, or replaced by, a comprehensive filtration system. For emergency situations involving potential biological threats, boiling is a reliable solution. For everyday use, especially if there are chemical concerns, a certified filtration method such as activated carbon or reverse osmosis is the safest approach.
Frequently Asked Questions
1. Can boiling remove lead from water? No, boiling water does not remove lead. Lead is a heavy metal with a high boiling point, so it remains in the water. As some water evaporates during boiling, the lead concentration actually increases.
2. Is boiled water the same as distilled water? No, they are not the same. Boiling simply heats water to kill microbes, leaving behind minerals and chemicals. Distillation involves collecting the condensed steam, which is free of impurities that don't evaporate, creating much purer water.
3. Does boiling water remove chlorine? Boiling can remove some free chlorine, as it is a volatile chemical. However, this method is less effective for the more stable compound chloramine, and it won't remove harmful disinfection byproducts.
4. What about harmful chemicals that are volatile? While volatile chemicals might evaporate with the steam, it is not a safe removal method. Inhaling these airborne chemicals can be dangerous, and the process doesn't guarantee complete removal.
5. Should I boil my water during a boil water advisory? Yes, during a boil water advisory, you should boil your water for the recommended time (typically 1–3 minutes) to kill potential biological pathogens like bacteria and viruses. These advisories are typically issued for microbial concerns, not chemical contamination.
6. What is the best way to remove both biological and chemical contaminants? For the most comprehensive water purification, a multi-stage filtration system combining technologies like activated carbon, reverse osmosis, or UV treatment is most effective. This addresses both microbial and chemical threats.
7. Does boiling remove pesticides and pharmaceuticals? No, many pesticides and pharmaceuticals are heat-resistant compounds that will not be removed by boiling. Their concentration can increase as water evaporates.
