Water is critical for life, especially in hot/dry areas like deserts.

Vandwellers living minimally (no showers or slip-n-slides) will typically require 1 gallon of potable water every day for drinking, and 1 additional gallon for cleaning, hygiene, cooking, etc.

drinking has the highest requirements since it is typically consumed untreated and at room temperature.

It is safest to start with known-drinkable water from public or commercial sources. It is possible to disinfect suspect water by several means; it is not practical to purify water that is chemically or minerologically tainted.

The first step in any disinfection routine is to clarify the water to remove haze or foreign matter. Much sediment can clear itself to the bottom if allowed to rest; pour or siphon off the top and leave the sediment behind.

Strain from coarse to fine: through a strainer then a coffee filter, for example.

Boiling is the most certain way of killing all microorganisms. According to the Wilderness Medical Society, water temperatures above 160F (70C) kill all pathogens within 30 minutes and above 185F (85C) within a few minutes. So in the time it takes for the water to reach the boiling point (212F or 100C) from 160F (70C), all pathogens will be killed, even at high altitude.²⁾

Given that information, solar ovens or similar devices that can hold 160F for long periods may provide unpowered heat disinfection.

The most famous treatment is chlorine bleach. For these purposes, unscented cheap bleach is better than $$$ bleach with additives. It is used at 8 drops/gallon and then wait 30 minutes.³⁾ Note that bleach purfication does not reliably kill Cryptosporidium. Increasing wait time to 45mins will kill norovirus and giardia.

Bleach is cheapest by the laundry bottle but is also available as tablets. An eye dropper bottle will store and dispense l1quid bleach accurately.

Iodine tablets were popular with hikers in the past but impart a noticeable flavor to the water. Some come with an additional tablet to be used after the waiting period, intended to remove iodine flavor and color from the water.

Treated water can be run through a charcoal filter (Brita) after treatment to improve flavor.

1-micron filters will filter Cryptosporidium out of clear water.⁴⁾

Water for cooking has lower requirements because the water is usually boiled during preparation.

cleaning

hygiene

Washwater (non-sewage waste water) is usually stored in a gray tank for later handling.