Water refill guide
Distilled vs. reverse osmosis vs. spring water
Spring
A source
Where the water comes from
Filtered
A treatment
What is done to the water
Short answer: distilled water is boiled into steam and condensed. Reverse osmosis water is pushed through a very fine membrane. Both remove most dissolved minerals and count as filtered water. Spring water flows up from underground and keeps its natural minerals, and at an open spring it isn't treated.
Our pick: reverse osmosis for everyday drinking. It's the treatment the CDC says removes parasites, bacteria, viruses and some chemicals, and it's the easiest to find: more than 7,000 stations in our directory list reverse osmosis. Its listed prices ($0.25 to $0.70 a gallon) also run below the spring water refills we list ($0.50 to $1.50). No station in our directory lists distilled water yet, so we have no distilled prices to compare. Want minerals? Pick spring water from a station or bottler, or add mineral drops to your RO. Save distilled for appliances whose manuals call for it.
Comparison
| Distilled | Reverse osmosis | Spring | |
|---|---|---|---|
| How it's made | Boiled into steam, then condensed | Pushed through a membrane, usually with pre- and post-filters | Flows naturally to the surface from underground |
| Minerals | Most dissolved solids stay behind | Most dissolved minerals removed | Keeps natural minerals. Varies by source |
| What the CDC says it removes | Parasites, bacteria, viruses and many chemicals. Not some volatile organic compounds | Parasites, bacteria, viruses and some chemicals | n/a: untreated at open springs |
| Taste | Very flat to many people | Plain | Distinctive, varies |
| Common uses | Appliances when the manual calls for it | Everyday drinking, coffee, cooking | People who prefer untreated or mineral water |
| Where to fill | Usually bought bottled. Rarely sold at refill machines | Most refill machines and water stores | Natural springs and some water stores |
Removal facts come from the CDC's home water treatment guide.
Cost, speed and upkeep
The CDC says distillation uses more energy and takes longer than other treatment methods, and that bacteria can grow on a distiller's cooling coils when it isn't being used. Home RO systems are faster but produce reject water, according to the EPA. At refill machines, all of that is the operator's cost. You pay per gallon.
Which should you choose?
It depends on what the water is for. Here's what we'd pick in each case:
- For a CPAP, iron or humidifier: follow the manual. Many call for distilled.
- For everyday drinking at low cost: reverse osmosis from a refill machine is the most widely available option.
- For natural minerals and taste: spring water. At an open spring, read posted signs, and treat the water if you're unsure. Some state health departments, including New York's and Maine's, advise against drinking from untreated roadside springs.
Alkaline and deionized?
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General information, not medical advice.