Water Quality
Summary
Your tap water probably contains more contaminants than you’d expect. Try to drink water that has been purified by a reverse-osmosis or other NSF-certified system. Try to drink water with a neutral pH.
Problem: Contaminants
Chemical byproducts from industry find their way into the water supply. Pharmaceuticals that are not completely metabolized are excreted in the urine and re-enter the water supply. Municipal water treatment plants cannot effectively remove many of these contaminants1. To see what’s in your water, search the EWG’s Tap Water Database. Keep in mind what’s considered “legal” may not necessarily by safe - legal limits for contaminants in tap water have not been updated in over 20 years2.
Common contaminants include:
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PFAS - Interfere with hormone and cholesterol levels and increase the risk of some cancers3. The EWG reported on 01/22/2020 that “PFAS is likely detectable in all major water supplies in the U.S.”
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Pharmaceuticals - Mood-altering drugs (antidepressants/SSRIs), antibiotics, painkillers, and more enter the water supply through various routes4. Although the concentrations of these may be relatively low, the full long-term effects of chronic exposure are not yet known.
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Heavy Metals - Lead leaches into water from old (pre-1986) pipes and plumbing fixtures5. Arsenic, mercury, and cadmium can also find their way into water6. All of these are classified as carcinogenic by the EPA7.
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Chlorine and related compounds - Usually byproducts of disinfection. Not likely to involve health effects unless an individual is allergic, but they make water taste and smell unpleasant8.
Solution: Purification
What can we do about these contaminants? One could go overboard and start panicking that our water is going to turn the frogs gay9, but it certainly can’t hurt to work toward drinking the cleanest water possible. Effective water purification is a tricky task - many manufacturers spread misinformation about purification techniques or misrepresent the performance and limitations of their systems.
NSF / ANSI Standards
Given the general shadiness of the purification market it would help if there was some set of trusted standards to which products could be held. Luckily, NSF International provides such standards10.
These standards provide a valuable independent benchmark for comparing purification systems. However, one caveat is that companies can pick and choose individual contaminants when applying for a given certification (an NSF 53 certification for one product may cover more contaminants than an NSF 53 certification for a different product).
With this in mind, I would recommend searching the NSF database for products carrying the following certifications while you shop:
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Aesthetic Effects (NSF/ANSI 42) - removal of chlorine and similar compounds affecting the taste of water.
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Health Effects (NSF/ANSI 53) - removal of contaminants with health effects including lead, mercury, cysts, VOCs, etc.
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Emerging Contaminants (NSF/ANSI 401) - removal of “emerging” contaminants including many pharmaceuticals (Atenolol, Carbamazepine, Ibuprofen, Naproxen, Trimethoprim) and carcinogens / hormone disruptors (BPA, TCPP, TCEP).
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PFAS (NSF P473) - removal of PFOA and PFOS.
Gravity Filtration
Pull water through a charcoal/ceramic/etc. filter using gravity.
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Pros: Easy to use. Requires no electricity or installation. Improves taste of water.
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Cons: Ineffective for removing many contaminants. Recurring filter costs.
All pitcher-style filters (Brita, Pur, ZeroWater, etc.) fall into this category. I have owned a Brita pitcher and a ZeroWater pitcher; both mostly reduced the chlorine taste but filters went bad quickly. If they hold any NSF certifications it’s usually only for NSF/ANSI 42, occasionally the heavy metal component of NSF/ANSI 53. These are better than nothing and may be acceptable for many people, but more thorough alternatives exist.
RECOMMENDED: the Clean Water Machine is a variation on this class of filtration - it uses an electric pump to force water through a filter instead of gravity. I have used one for a few weeks and it is LOUD while running (for the ~30 seconds to filter a pitcher) but the water tastes good. It holds certifications for NSF/ANSI 42, 53, 401, and P473 and has an impressive Performance Data Sheet.
NOT RECOMMENDED: large gravity filters like Propur and Berkey may be slightly better than the “pitcher” class of filters. Despite impressive-looking “independent lab results” (which some have called into question11), Berkey holds no NSF certifications and Propur only holds NSF/ANSI 42. These filters also often make the resulting water fairly alkaline. I have used a Propur Big for many years and it resulted in water that tasted nice but gave me subtle GI side effects (possibly from the increased alkalinity or other contaminants?).
Reverse Osmosis
Force water through a semipermeable membrane by applying pressure.
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Pros: Very clean water, almost all contaminants removed.
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Cons: May require complex installation. May waste a lot of water (potentially
1:4 clean:waste). Recurring filter costs.
Under-sink and whole-house RO systems are common. Counter-top systems exist but are rare. Systems often combine multiple steps (sediment pre-filters, carbon filters, a remineralization step, etc.).
If you have the capability to install one, an under-sink reverse osmosis system is probably the way to go.
RECOMMENDED: I recently installed this Home Master RO System and although it lacks meaningful NSF/ANSI certifications (some of the individual components may be certified), it has a much better design - it hasn’t leaked a drop and the water is great quality.
NOT RECOMMENDED: this Aquasana RO system has certifications for NSF/ANSI standards 42, 53, 58, 401, and P473 - HOWEVER, it has very cheap plastic parts (and a plastic filter manifold) which leaked constantly after I installed it - I have since returned the unit.
Distillation
Boil water then cool the steam until it re-condenses.
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Pros: Clean water, many contaminants removed. Water is sterilized. No installation required. No recurring filter costs.
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Cons: Uses a lot of energy. Takes a while. Some volatile chemicals may persist through distillation (unclear).
Counter-top systems exist. Systems occasionally include a charcoal post-filter.
RECOMMENDED: this countertop distiller has performed well for me for many years - I run it overnight and only occasionally have to de-scale it with a citric acid solution.
Shower Filters
While we’ve mainly focused on drinking water, you can get exposed to the same contaminants while showering. There is early evidence for PFAS being able to be absorbed through the skin 12. Individuals with sensitive skin or chlorine allergies may also benefit from removing chlorine and related compounds from the water they shower in.
One should keep in mind the efficacy of these products may be questionable - higher volumes of water passing more quickly through smaller filters will result in less effective reduction of contaminants.
RECOMMENDED: I use the ProPur shower filter, which seems to do a decent job. I have not used the AquaBliss shower filter, but it also looks promising.
Note: Alkalinity
Despite many health enthusiasts claiming drinking alkaline water is a good idea, I have yet to see any credible evidence that this is the case. Drinking overly-alkaline water may negate the (desirable) effects of stomach acid and worsen digestion. Drinking overly-acidic water may weaken tooth enamel over time. Therefore, it seems reasonable to drink water with as close to a neutral pH (7) as possible.
You can guesstimate the pH of your water with test strips or a pH meter. If your water is too alkaline, consider adding a few drops of lemon juice to bring the pH closer to neutral. If your water is too acidic, consider adding trace minerals including calcium and magnesium to your water.