WHAT DISTILLATION IS
Distillation does not strain water. It changes water into steam and then back into liquid in a clean vessel. Almost everything that was dissolved or suspended stays behind.
The idea is old. Nature does a version of it every time the sun lifts vapor off the sea and rain falls inland. An alembic, a shipboard still, a laboratory condenser, a home countertop unit, and a multi-stage flash desalination plant are the same physics at different scales.
Four steps, always:
A good household still adds two extras: a small vent so light gases and some volatile organics can escape before they condense, and a carbon post-filter to catch whatever still rode along with the steam. Without those, distillation is incomplete.
WHAT IT REMOVES
Typical well-run distillation takes out about 99.5% of dissolved solids.
Reliable against: bacteria, viruses, protozoan cysts; dissolved salts and hardness; heavy metals (lead, mercury, cadmium, arsenic, chromium, barium); nitrate and nitrite; fluoride; many radionuclides; most non-volatile organics; sediment, rust, microplastics as particles; PFAS in practice (pair with carbon if you want belt and suspenders).
Not reliable, by itself, against: volatile organic compounds whose boiling points sit at or below water’s (benzene, chloroform, TCE, MTBE, some pesticides and fuel fractions); dissolved gases that come over with the first steam; anything you add after the fact with a dirty collection jug.
That VOC hole is the main technical argument against “distillation is perfect.” A vent plus carbon is part of a serious still.
HOW OTHER METHODS WORK
Boiling alone. Kills microbes. Does not remove metals, salts, nitrate, fluoride, or most chemicals. You drink a more concentrated soup if you boil a pot down. Distillation is boiling plus a phase change and a clean landing place.
Sediment filters. Catch grit. Nothing dissolved.
Activated carbon. Adsorption. Excellent for chlorine, taste, odor, many VOCs and pesticides, and — if certified NSF/ANSI 53 or 401 — lead, some PFAS, cysts. Useless as a rule against nitrate, fluoride, arsenic, hexavalent chromium, and dissolved salts. Carbon saturates. When it is spent it can dump what it held.
Ceramic and hollow-fiber. Physical pores. Good for bacteria and protozoa, not viruses unless the rating is extreme. Not for dissolved ions.
Ultraviolet. Light damages microbial DNA. No chemical removal. Water must already be clear. No residual protection in the jug.
Ion exchange. Swaps ions. Softeners trade sodium or potassium for calcium and magnesium. Specialty resins can grab nitrate or arsenic. They do not disinfect and they do not strip a broad mixed plume.
Reverse osmosis. Pressure forces water through a membrane. With carbon pre- and post-filters it is the widest practical home filter. It takes out TDS, metals, fluoride, nitrate, arsenic, chromium-6, most PFAS, and a large share of organics. Weak spots: it wastes 2–4 gallons for every gallon kept (better units do less), membranes foul, chlorine must be stripped first, it is not a certified sterilizer by itself, and it still needs power and pressure. Like distillation, it also strips useful minerals.
Deionization. Resins pull ions until they are exhausted. Laboratory polish, not a stand-alone drinking system for a dirty well.
WHY DISTILLATION WINS ON SOME JOBS
The impurity stays in the pot. When the feed is unknown, variable, or extremely dirty — seawater, boiler blowdown, a well with mixed metals and bugs — that logic is simpler. Heat plus physical separation handles microbes. Same class as RO for salts, metals, nitrate, fluoride. No membrane to rot. A still needs heat, not city pressure. Product TDS near zero if the condenser is clean. Industrial heritage: MSF, MED, and mechanical vapor compression, especially where waste heat is cheap.
Thermal plants use more energy than seawater RO (roughly 6–25 kWh-equivalent per cubic metre thermal versus about 3–4 kWh/m³ for modern RO), but they tolerate dirtier, hotter, or more saline feed and pair naturally with power-station heat.
WHERE DISTILLATION LOSES
Energy: about 2,260 kJ to turn a kilogram of water into steam, before losses. A countertop still is slow (often 3–6 litres in several hours). Time and volume: not a whole-house cottage technology. VOCs without a vent and carbon. Dead water with almost no calcium, magnesium, or bicarbonate. Exclusive long-term drinking of un-remineralized water is not ideal. The boiler liquor is nastier than the feed. A still is an appliance that boils.
VERSUS EACH RIVAL, SHORT
Versus carbon pitcher: distillation takes the ions carbon never sees. Carbon is cheaper, faster, keeps minerals, and is often better at light solvents unless the still is vented and polished.
Versus UV: distillation removes chemicals UV never touches and does not need clear water.
Versus ceramic: distillation handles viruses and dissolved poison. Ceramic is a camping bacteria filter.
Versus softener: a softener swaps hardness for sodium. Distillation removes both.
Versus RO: closest rival. Distillation wins on microbial kill and on not needing pressure. RO wins on speed, household energy, and VOC handling with good carbon. RO wastes water; a still wastes heat.
Versus plain boiling: boiling sanitizes. Distillation purifies.
PRACTICAL NOTES
WHERE IT BELONGS
Laboratories, pharmacies, battery shops, humidifiers, marine evaporators, desert desalination next to a turbine, disaster water when fuel exists, and households that want a method whose failure mode is “the pot crusts up” rather than “the membrane tore and we did not notice.”
It is not magic and it is not the cheapest gallon. It is the method that moves the water and leaves the dirt in the fire.
IN ONE SENTENCE
Distillation boils water into steam and condenses that steam in a clean place, stripping salts, metals, hardness, fluoride, nitrate, and microbes more thoroughly than carbon or UV and as thoroughly as reverse osmosis for dissolved solids — at the price of energy, time, flat taste, and a known weakness for volatile chemicals unless you vent them and filter the product.