How Water Goes Bad: What Is Actually in It, Source by Source, and What Fixes Each One

Not on its own. Water has no shelf life; what changes is what grows in it or leaches into it. Clean tap water in a clean, sealed, food-grade container in the dark is safe for years. It tastes flat after months because the dissolved air leaves, which a good shake or pouring between two jugs fixes. What actually goes wrong is a dirty container, a lid left off, a drum in the sun growing algae, or a container that was never food-grade to begin with.

Open it and look, smell and check the container. Cloudiness, floating particles, a slime film on the walls, a green tint, or a musty, rotten-egg or chemical smell means treat it or dump it. A cracked, bulging or sun-faded container is a reason to move the water. Clear and odorless is a good sign but not proof: bacteria and most chemicals are invisible, so water you are unsure of gets boiled or chlorinated before it is drunk, and that costs a few minutes.

Every 6 to 12 months for taste, not safety. Water that was clean going in and sealed since is still clean; it just tastes flat. I drain the drums onto the garden in spring, rinse, refill and date them. Commercially bottled water is fine indefinitely if the seal is intact and it has been kept cool and out of the sun; the two-year date on the bottle is about the bottle, not the water.

Food-grade plastic marked HDPE (recycling 2) or PETE (1), such as new water drums, jerry cans, and washed soda and juice bottles. Glass is inert and heavy. Stainless steel is fine for plain water but not for chlorinated water or bleach solutions, which pit it. Never a container that held anything but food or drink: no milk jugs (protein residue feeds bacteria and the plastic fails in months), no chemical drums, no trash cans, no garden hose to fill them.

One gallon per person per day, and that is drinking plus a little cooking and washing. Two weeks is the target, three days is the bare minimum, and hot climates, illness, children and nursing mothers push it higher. A family of four for two weeks is 56 gallons: one 55 gallon drum, or a stack of jugs and cases. Pets drink too.

Something got into it: germs from sewage, animals or surface runoff; chemicals from fuel, farms, industry or a flood; metals from pipes or the ground; toxins from an algae bloom; or radioactive dust after a fallout event. Each has a source you can usually name and a fix that is specific to it. The one universal rule is that boiling handles the germs and nothing else.

Assume not until it is tested. Floodwater carries sewage, fuel and farm runoff straight down the casing and into the aquifer. Do not drink it, and do not run the pump into the house until the water recedes. Then shock chlorinate the well, flush it, and have it tested for bacteria and nitrates before anyone drinks from it. Until then it is bottled or stored water, or water boiled and filtered from the cleanest source you can find.

No. Boiling kills bacteria, viruses and parasites and does nothing to fuel, pesticides, solvents, nitrates, metals or algae toxins; because it boils off some of the water, it leaves those slightly more concentrated. Chemical contamination calls for activated carbon, reverse osmosis or distillation depending on the chemical, or a different source. A chemical smell in water is a reason to walk away from it, not to boil it longer.