# Outdoor Water & Hygiene

This leaf bundles two jobs: treating water you will drink, and washing up or disposing of waste without plumbing. For water, the question that matters is whether a product only strains out bacteria and protozoa, or also stops viruses, which a 0.1 to 0.3-micron filter cannot do alone.

## How it works

Untreated water carries three pathogen classes, ranked by size: protozoan cysts such as Giardia and Cryptosporidium (several microns), bacteria (about 0.2 to 2 microns), and viruses (about 0.02 to 0.3 microns). A mechanical filter straining pores at 0.1 to 0.3 microns catches cysts and most bacteria but misses most viruses; the trade calls this a filter. Add a step that also stops viruses, such as a chemical (iodine, chlorine, or chlorine dioxide), ultraviolet light, an electroadsorptive cartridge, or a 0.02-micron membrane, and it becomes a purifier. Boiling for 1 minute, 3 above 6,500 feet, kills all three regardless of pore size, at the cost of fuel and wait time. None of this applies to hygiene: washing, sanitizing and burying waste in the field work by distance and depth from water, not by killing pathogens. [1] [2] [3] [4]

| Family | What it is | Suits |
|---|---|---|
| Mechanical filters | Hollow-fiber, ceramic, or carbon cartridges strain out bacteria and protozoa at 0.1 to 0.3 microns. Fine for domestic backcountry water. | US and Canada backcountry trips where viruses are not the main risk. |
| Purifiers | Chemical tablets, UV pens, electroadsorptive press cartridges, or sub-0.05-micron pump membranes add virus protection on top of bacteria and protozoa. | International travel and water of unknown origin. |
| Boiling | A rolling boil for 1 minute, 3 above 6,500 feet, kills all three pathogen classes regardless of how muddy the water is. | A free backup method whenever there is a stove and fuel to spare. |
| Field hygiene | Soap, sanitizer, trowels and pack-out bags manage washing and human waste by distance and depth from water, not by killing pathogens. | Keeping camp, trail and water sources clean under Leave No Trace guidance. |

## How an expert narrows the choice

```mermaid
timeline
  section 1 · Primary job
    treat water : ask Filter or purifier, Form factor
    hygiene and cleanup : ask Hygiene task : skip Filter or purifier, Form factor, Treatment method, Filter pore size, Virus-rated standard claimed, Flow rate, Filter lifetime, Wait time before drinking, Needs clear water
  section 2 · Filter or purifier
    bacteria and protozoa only : ask Treatment method, Filter pore size, Wait time before drinking : skip Virus-rated standard claimed
    viruses too : ask Treatment method, Virus-rated standard claimed, Wait time before drinking, Filter pore size
  section 3 · Form factor
    drops or UV pen : ask Wait time before drinking, Needs clear water, Treatments per charge : skip Filter pore size, Filter lifetime
    pump / gravity bag : ask Flow rate, Filter lifetime : skip Wait time before drinking
    squeeze or straw : ask Filter lifetime
  section 4 · Hygiene task
    wash up : ask Biodegradable soap, Portable shower type, Alcohol percentage : skip Human waste method
    dispose of waste : ask Human waste method, Alcohol percentage : skip Biodegradable soap, Portable shower type
```

1. **Primary job.** Treating water to drink, or hygiene and cleanup?
   Routes everything downstream. A buyer treating water never needs soap or a trowel, and a hygiene buyer never needs pore size or virus protection, so this removes about half the facets either way.
   If treat water: ask Filter or purifier, Form factor.
   If hygiene and cleanup: ask Hygiene task; skip Filter or purifier, Form factor, Treatment method, Filter pore size, Virus-rated standard claimed, Flow rate, Filter lifetime, Wait time before drinking, Needs clear water.

2. **Filter or purifier.** US/Canada backcountry only, or traveling elsewhere?
   Whether viruses matter removes most of the catalog: a 0.1 to 0.3-micron mechanical filter cannot stop them, so unknown water or international travel needs a purifier instead.
   If bacteria and protozoa only: ask Treatment method, Filter pore size, Wait time before drinking; skip Virus-rated standard claimed.
   If viruses too: ask Treatment method, Virus-rated standard claimed, Wait time before drinking, Filter pore size.
   Skip if already known: destination is US or Canada backcountry only, an earlier answer already named a purifier.

3. **Form factor.** Squeeze, pump, gravity bag, or drops/UV pen?
   Sets weight, speed and group size at once. Squeeze and straw suit one person traveling light, pumps and gravity bags serve a few people or a group, and drops or a UV pen need no element to clean.
   If drops or UV pen: ask Wait time before drinking, Needs clear water, Treatments per charge; skip Filter pore size, Filter lifetime.
   If pump or gravity bag: ask Flow rate, Filter lifetime; skip Wait time before drinking.
   If squeeze or straw: ask Filter lifetime.

4. **Hygiene task.** Washing up, or dealing with waste?
   Separates two Leave No Trace jobs: keeping soap and bodies 200 feet from water, against burying or packing out what the body leaves behind.
   If wash up: ask Biodegradable soap, Portable shower type, Alcohol percentage; skip Human waste method.
   If dispose of waste: ask Human waste method, Alcohol percentage; skip Biodegradable soap, Portable shower type.

## What to surface

### Primary job

Whether the product treats water to make it safe to drink, or handles washing and waste disposal in the field. The leaf bundles two expert domains that never trade against each other: water microbiology and Leave No Trace field hygiene. Knowing which one a buyer wants throws out half the register immediately, since a water filter buyer has no use for soap distance rules and a trowel buyer has no use for pore size.

Values: treat water, hygiene and cleanup.
Question to ask: Treating water to drink, or hygiene and cleanup?

Used as: top-level split, filter. Data: on the listing, backfill cost none. Look for it as: Product title and category: filter, purifier, tablets, pen, versus soap, shower, trowel, waste bag.

### Filter or purifier

Whether the product only strains out bacteria and protozoa (a filter) or also stops viruses (a purifier), the trade's own split. Filters work by straining pores at 0.1 to 0.3 microns, which is fine for most bacteria and protozoa but too coarse for most viruses. Purifiers add a chemical, UV, finer-membrane, or electroadsorptive step that also handles viruses. US and Canada backcountry water is mostly a filter problem; water of unknown origin, or travel to places with weaker sanitation, is a purifier problem. [2] [1] [3]

Values: bacteria and protozoa only, viruses too.
Question to ask: US/Canada backcountry only, or traveling elsewhere?

Used as: top-level split, filter, shown on the card. Data: on the listing, backfill cost low. Look for it as: The product name itself: 'filter' (Sawyer Squeeze Filter, Katadyn BeFree) versus 'purifier' (Grayl GeoPress Purifier, MSR Guardian Purifier). Confirming the compliance claim behind the word needs the brand page.
The filter/purifier word in the product name is reliable; one brand-page read confirms which standard, if any, backs it.
Chart: Pathogen size ladder.

### Form factor

How the water moves through the treatment: squeezed or sipped through a straw, pumped, hung to drip by gravity, or dosed with drops, tablets, or a UV pen. This sets weight, group size and effort together. Squeeze and straw filters are lightest and serve one person. Pumps push water on demand for a few people. Gravity bags process the most water with the least effort but need somewhere to hang and are bulkier. Chemical drops and UV pens have no element to clean but add a wait or a battery. [2]

Values: squeeze or straw, pump, gravity bag, drops or UV pen.
Question to ask: Squeeze, pump, gravity bag, or drops/UV pen?

Used as: top-level split, filter, shown on the card. Data: on the listing, backfill cost none. Look for it as: Title words: squeeze, bottle, straw, pump, gravity, drops, tablets, UV, pen.
Chart: Method comparison matrix.

### Hygiene task

Whether the hygiene need is washing up (body, hands, dishes) or disposing of human waste. Leave No Trace treats these as two separate jobs with two separate rules: wash water and soap go 200 feet from any water source, while solid waste goes in a buried cathole or a pack-out bag depending on whether digging is possible. Knowing which job narrows straight to soap or shower facets, or to the waste-disposal facet. [4]

Values: wash up, dispose of waste.
Question to ask: Washing up, or dealing with waste?

Used as: top-level split, filter. Data: on the listing, backfill cost none. Look for it as: Product category: soap, wash, shower versus trowel, waste bag, toilet kit.

### Biodegradable soap

Whether the soap or wash is marketed as biodegradable for outdoor use. Biodegradable soap breaks down in soil with the help of microbes, not in water, so it still has to be used 200 feet from any stream or lake and the wastewater strained and scattered. A buyer who thinks 'biodegradable' means safe to pour straight into a lake is acting on the label, not on what Leave No Trace actually asks for. [4] [2]

Question to ask: Need it to be biodegradable for the backcountry?

Used as: filter, shown on the card. Data: on the listing, backfill cost none. Look for it as: Title or bullets say 'biodegradable' directly.

### Portable shower type

How the shower delivers water: a sun-heated gravity bag, a foot- or hand-pumped pressurized tank, or a propane-heated on-demand unit. A solar gravity bag is the lightest and cheapest but gives low, un-pressurized flow and needs sun and a branch to hang from. A foot-pump tank gives several minutes of steady, hands-free spray with no battery or fuel. A propane unit heats water on demand but is heavier and needs fuel, so it suits car camping rather than backpacking. [16]

Values: solar gravity bag, foot or hand pump, propane heated.
Question to ask: Sun-heated bag, foot pump, or propane?

Used as: filter, shown on the card. Data: on the listing, backfill cost none. Look for it as: Title words: solar shower, pressure shower, foot pump, propane, on-demand.

### Human waste method

Whether the product supports digging and burying waste (a trowel) or sealing and packing it out (a WAG bag kit). Leave No Trace's default is a cathole 6 to 8 inches deep and at least 200 feet from water, trails and camp. Where ground cannot be dug, such as snow, rock, or heavily used alpine routes, the alternative is a gelling pack-out bag. Buying the wrong one for the terrain means either an impossible hole or an unnecessary bag to carry. [4] [15]

Values: trowel and cathole, pack-out bag (WAG bag).
Question to ask: Dig and bury, or bag and carry out?

Used as: filter, shown on the card. Data: on the listing, backfill cost none. Look for it as: Title says 'trowel' or 'WAG bag' / 'waste disposal bag' directly.

### Virus-rated standard claimed

Which named testing standard, if any, the product cites as proof it meets a recognised bar for removing or inactivating viruses. The word 'purifier' on its own is marketing; the standard behind it is the fact. MSR cites NSF protocol P248, the US military's standard; Grayl cites the EPA's Guide Standard and Protocol, the same log-reduction bar (99.9999 percent bacteria, 99.99 percent viruses, 99.9 percent protozoan cysts). Many products state neither and simply list which pathogens they claim to remove. [11] [12]

Values: not stated, meets EPA Guide Standard, meets NSF P248 (military), NSF/ANSI 42 or 53 only.

Used as: filter, shown on the card. Data: needs research, backfill cost medium. Look for it as: Rarely in titles; usually a sentence on the brand's product or FAQ page, sometimes only in a downloadable spec PDF.
Needs a brand-page or FAQ read per product; absent is common and should be recorded as 'not stated' rather than assumed to fail.

### Filter lifetime

How many liters the filter or cartridge is rated to treat before it needs replacing or stops being field-cleanable. This is the real cost of ownership, and it varies enormously by technology, not by price: a hollow-fiber squeeze cartridge is rated for 200 to 1,000 L, while a scrubbable ceramic or a self-cleaning pump cartridge is rated for 10,000 to 50,000 L. A cheap filter that dies at 200 L can cost more per liter than an expensive one rated for 50,000. [6] [7] [11] [5]

Range: 200 to 50000 L. Hollow-fiber squeeze and bottle filters: 200 to 1,000 L. Ceramic and self-cleaning pump purifiers: 10,000 to 50,000 L.

Used as: shown on the card, sortable, filter. Data: needs research, backfill cost low. Look for it as: On the brand's spec table as a liter figure; Sawyer instead backs its filter with a lifetime warranty and states no liter number at all.
Stated on the brand page for most products; where only a warranty is offered instead, record the lifetime as unknown rather than estimating one.
Chart: Capacity against weight.

### Treatment method

The underlying technology doing the work: hollow-fiber membrane, ceramic, activated carbon, a chemical, UV light, an electroadsorptive cartridge, or boiling. The method decides what the product can and cannot remove, independent of the filter-or-purifier label. Chlorine dioxide kills viruses and Giardia well but is only low to moderate against Cryptosporidium; iodine does not touch Cryptosporidium at all; UV needs clear water to reach pathogens; hollow fiber and ceramic physically strain cysts and bacteria but not viruses. [1] [5] [6] [7] [8] [9] [11] [12]

Values: hollow fiber membrane, ceramic, activated carbon, iodine, chlorine dioxide, UV light, electroadsorptive cartridge, boiling.

Used as: filter, shown on the card. Data: needs research, backfill cost low. Look for it as: Sometimes in the title ('hollow fiber', 'ceramic', 'UV', 'iodine'); the chemistry behind 'purifier' claims is usually only on the brand's FAQ page.
One brand-page or FAQ read per product settles it.
Chart: Pathogen size ladder.

### Filter pore size

The smallest particle size, in microns, the filter membrane is rated to physically strain out. This is the number a filter's bacteria and protozoa claims rest on, and the one that shows why viruses usually get through: a finer pore (MSR Guardian's 0.02 microns) catches more but clogs faster on silty water, while a coarser pore (0.1 to 0.2 microns on most squeeze filters) flows faster when fresh but still misses most viruses. [5] [7] [11]

Range: 0.02 to 0.2 µm. Hollow-fiber squeeze and bottle filters sit at 0.1 to 0.2 microns. Ceramic filters are around 0.2. Purifier-grade pumps go down to 0.02.

Used as: filter, sortable, shown on the card. Data: needs research, backfill cost low. Look for it as: On the brand's spec table, almost never in marketplace titles.
Every brand page read for this register stated it outright.
Chart: Pathogen size ladder.

### Wait time before drinking

How many minutes must pass between treating the water and it being safe to drink. Mechanical filters and a Grayl press are drinkable in seconds. UV pens treat a liter in 48 to 90 seconds but need another dose for more. Chemical tablets need 30 minutes to 4 hours, longer in cold water, which is the main reason people carry them only as a backup rather than a primary method. [8] [9] [12] [2]

Range: 0 to 240 min. Near-instant for filters and press-style purifiers. 1 to 2 minutes for UV, per liter. 30 minutes to 4 hours for chemical tablets or drops.

Used as: shown on the card, sortable. Data: needs research, backfill cost low. Look for it as: Chemical products state it clearly on the label; UV products state seconds per liter on the spec page.
Reliable on the brand or label page for the methods that have a wait at all.
Chart: Method comparison matrix.

### Needs clear water

Whether silty or cloudy water meaningfully hurts the device's performance or safety, so a prefilter or settling step is needed first. UV purifiers stop working reliably in cloudy water because the light cannot reach pathogens hiding behind particles, and chemical disinfectants work slower and less completely in turbid or cold water. Boiling and most mechanical filters with a prefilter accessory tolerate murky water, at the cost of clogging faster. [9] [2]


Used as: filter, shown on the card. Data: needs research, backfill cost low. Look for it as: Stated as a warning on UV products ('use only on clear water'); rarely flagged for chemical or mechanical products.
One brand-page read settles it; UV products are reliably yes, most filters effectively no if a prefilter accessory exists.

### Flow rate

How many liters of water the device can produce per minute of effort. This is the number that decides whether filling a group's bottles is a two-minute job or a ten-minute one. It ranges from about 1 L/min on a pump-style ceramic filter to a burst of roughly 5 L/min pressing a Grayl GeoPress, and it drops as a filter element clogs. [6] [7] [11] [12]

Range: 1 to 5 L/min. Pumps and gravity systems give 1 to 2.5 L/min continuously. Press-style purifiers deliver a faster burst per stroke.

Used as: shown on the card, sortable. Data: needs research, backfill cost low. Look for it as: Sometimes in bullet points, more reliably in the brand's spec table.
Stated on the brand page for every product in this research except Sawyer, which gives no flow figure at all.
Chart: Method comparison matrix.

### Alcohol percentage

The percentage of alcohol, by volume, in a hand sanitizer. The CDC's bar for an effective hand sanitizer is at least 60 percent alcohol, with 60 to 95 percent being the most effective band; most products sit at 60 to 80 percent. Below that, there may not be enough contact time to kill germs. Even at full strength, alcohol sanitizer does not reliably kill Cryptosporidium or norovirus, so soap and water stays the standard for visibly dirty hands. [13] [14]

Range: 60 to 95 %. Most products sit between 60 and 80 percent alcohol.

Used as: filter, shown on the card. Data: on the listing, backfill cost low. Look for it as: Printed on the bottle's front label as a percentage.
Reliably on the label; a photo settles it when the listing omits it.

### Treatments per charge

How many liters a UV pen can treat on one battery charge before it needs recharging or a battery swap. A UV pen's lamp itself lasts thousands of activations, but the battery runs out far sooner: Katadyn's rechargeable SteriPEN Ultra gives 50 treatments per internal charge, while its AA-powered Classic 3 gives about 100 per set of NiMH batteries. That gap decides whether a multi-day trip needs a spare battery or a power bank. [9] [10]

Range: 50 to 100 treatments. Rechargeable internal-battery pens: about 50 treatments per charge. AA-powered pens: roughly 100 per set of NiMH batteries.

Used as: shown on the card, sortable. Data: needs research, backfill cost low. Look for it as: On the brand's spec table, under battery or treatments-per-charge; rarely in titles.
Stated on the brand spec table for every UV pen read for this register.

## Numbers worth computing

| Metric | Formula | Why |
|---|---|---|
| Cost per liter treated (currency per L) | `price / filter_lifetime_l for a reusable filter or cartridge; price_per_tablet / 1 for a chemical tablet, since one tablet treats about one liter` | The number that actually matters over a season. A cheap filter rated for 200 L can cost more per liter than an expensive one rated for 50,000, and a box of tablets has a real per-liter price too. [6] [7] [11] [8] |
| Minutes to fill a group's bottles (min) | `liters_needed / flow_rate_lpm` | What a pump or gravity system actually costs in camp time before dinner, since a liters-per-minute spec alone does not say how long a group waits for water. [7] [11] [2] |

## What you give up

- MSR's 0.02-micron pump membrane catches viruses but needs a self-cleaning piston and still slows in silty water. Sawyer's and Katadyn's coarser 0.1 to 0.2-micron hollow fiber flows faster when fresh but cannot touch viruses at all. [11] [5] [6] [3] Board branch: "See more virus-rated purifiers".
- Chemical tablets need up to 4 hours' wait, UV pens need batteries and clear water, and electroadsorptive press cartridges need real hand force. A filter that only targets bacteria and protozoa is faster, lighter, and needs none of that. [8] [9] [12] [2] Board branch: "See more fast mechanical filters".
- A gravity bag processes a group's water with no pumping, but it is bulkier than a squeeze filter and needs a branch or pole to hang from, which some campsites and shorelines do not have. [2] Board branch: "See more lightweight personal filters".
- Biodegradable soap still needs soil microbes to break it down, not water, so Leave No Trace asks for the same 200-foot walk from any stream or lake regardless of the label. [4] [2]

## How to draw it

**Pathogen size ladder** (scale, shows Filter pore size, Treatment method, Filter or purifier). A horizontal micron scale with protozoa, bacteria and virus size bands marked, and each product's pore size or method plotted against them, so a buyer sees at a glance why a 0.2-micron filter misses viruses. This is a proposal, nobody draws it this way yet. [1] [3]

**Method comparison matrix** (other, shows Form factor, Flow rate, Filter lifetime, Wait time before drinking). One row per form factor, with marks for all-around performance, volume, low maintenance, ease of use, low weight, low cost and speed, so trade-offs across methods show at a glance. Used today by REI Co-op's own buying-guide table. [2]

**Capacity against weight** (two axis map, shows Filter lifetime). Liters a filter or cartridge is rated for on one axis against its weight on the other, showing why a heavy ceramic filter good for 50,000 liters and a light squeeze filter good for a season sit in opposite corners. This is a proposal, nobody draws it this way yet. [7] [6]

## Words you will meet

- **Filter vs purifier**. Trade terms: a filter strains out bacteria and protozoa; a purifier adds a step that also stops viruses.
- **Micron**. A millionth of a meter, the unit filter pore sizes and pathogen sizes are measured in.
- **Log reduction**. How completely a method removes a pathogen: 3-log is 99.9 percent, 4-log is 99.99 percent, 6-log is 99.9999 percent.
- **Hollow fiber membrane**. A bundle of straw-like fibers with pores small enough to strain out bacteria and protozoa as water is pushed or sucked through.
- **Electroadsorption**. A cartridge that uses an electric charge to pull in particles finer than its pores can physically strain, including viruses.
- **Turbidity**. How cloudy or silty water is. Cloudy water clogs filters faster and blocks UV light from reaching pathogens.
- **Cathole**. A hole dug to bury human waste, kept well away from water, trails and camp.
- **WAG bag**. A pack-it-out kit that gels and seals human waste for carrying out where digging a hole is not possible.
- **Leave No Trace**. The backcountry ethics group whose seven principles set the usual distances and depths for washing and waste disposal.
- **Graywater**. Used wash or dish water, which Leave No Trace says to strain and scatter well away from water sources.

## Where we made a call

- A 0.1 to 0.3-micron mechanical filter removes bacteria and protozoa but not viruses. (confidence high). CDC calls filtration 'not effective' against viruses. Wikipedia gives 0.3 microns as the largest virus any filter catches. Sawyer and Katadyn BeFree make no virus claim at their stated pore sizes. [1] [3] [5] [6]
- Grayl's quoted removal percentages match the EPA Guide Standard's own log-reduction thresholds for bacteria, viruses and protozoa. (confidence medium). Sources disagree. Grayl also cites NSF/ANSI 42 and 53, which test taste and particulates, not viruses specifically. The EPA standard, not those two NSF numbers, is what actually backs the virus claim. [12]
- Biodegradable soap must still be used 200 feet from water; the label describes decomposition, not safety in a stream. (confidence high). Leave No Trace and REI both give the same 200-foot rule for washing, independent of whether the soap is labelled biodegradable. [4] [2]
- Hand sanitizer at 60 percent alcohol or more meets CDC's bar but does not reliably kill Cryptosporidium or norovirus. (confidence high). CDC names Cryptosporidium, norovirus and C. difficile as pathogens alcohol sanitizer does not reliably inactivate, so soap and water remains the backup for visibly dirty hands. [13]

## References

1. [CDC, A Guide to Drinking Water Treatment and Sanitation for Backcountry and Travel Use](https://www.cdc.gov/healthywater/drinking/travel/backcountry_water_treatment.html) (regulator). Supports: boiling 1 minute, 3 above 6,500 feet, kills all pathogen classes; filtration at 1 micron or less removes cysts with high effectiveness; filtration at 0.3 micron removes bacteria with only moderate effectiveness; filtration is not effective against viruses; iodine and chlorine are not effective against Cryptosporidium.
2. [REI Co-op, Choosing a Backpacking Water Filter](https://www.rei.com/learn/expert-advice/water-treatment-backcountry.html) (primer). Supports: the filter versus purifier trade distinction, by virus removal; pros and cons of pump, gravity, UV, bottle, squeeze, straw and chemical methods; boiling 1 minute, 3 above 6,500 feet; the 200-foot Leave No Trace distance for camp, toilet and dishwashing.
3. [Wikipedia, Portable water purification](https://en.wikipedia.org/wiki/Portable_water_purification) (primer). Supports: 0.2 to 0.3 micron pump filters miss most viruses except the largest; not all bacteria are removed by 0.2 micron pump filters; chlorine and iodine alone are not fully effective against Cryptosporidium.
4. [Leave No Trace, Principle 3: Dispose of Waste Properly](https://www.lnt.org/why/7-principles/dispose-of-waste-properly/) (standards body). Supports: catholes dug 6 to 8 inches deep, at least 200 feet from water, camp and trails; wash yourself or dishes 200 feet from water, with small amounts of biodegradable soap; pack out waste where a cathole cannot be dug; hand sanitizer avoids wastewater disposal entirely.
5. [Sawyer Products, Squeeze Water Filtration System](https://www.sawyer.com/products/squeeze-water-filtration-system/) (spec sheet). Supports: 0.1 micron absolute hollow-fiber filter; removes 99.99999% of bacteria and 99.9999% of protozoa; no virus removal claim; backed by a lifetime warranty rather than a stated liter rating.
6. [Katadyn, BeFree Filter AC 1.0L](https://katadyn.com/products/8021403-katadyn-befree-filter-ac-1-0l-black) (spec sheet). Supports: hollow-fiber plus activated-carbon two-stage filter; up to 2 L/min flow; hollow fiber rated to 1,000 L, carbon stage to 200 L; no virus removal claim.
7. [Katadyn, Pocket Water Filter](https://katadyn.com/products/2010000-katadyn-pocket-water-filter) (spec sheet). Supports: 0.2 micron silver-impregnated ceramic filter; field-cleanable, rated up to 50,000 L; about 1 L/min output.
8. [Katadyn, Micropur MP1 Water Purifier Tablets](https://katadyn.com/products/8014996-katadyn-micropur-mp1-water-purifier-tablets-package-of-20) (spec sheet). Supports: 4-hour exposure time; effective against bacteria, protozoa, cysts and viruses; one tablet treats one liter.
9. [Katadyn, SteriPEN Ultra UV Water Purifier](https://katadyn.com/products/ult-mp-efg-katadyn-steripen-ultra-uv-water-purifier) (spec sheet). Supports: treats 1 L in 90 seconds or 0.5 L in 48 seconds; use only on clear water; cloudy water hinders effectiveness; inactivates bacteria, protozoa and viruses; lamp life 8,000 activations; 50 treatments per internal battery charge.
10. [Katadyn, SteriPEN Classic 3 UV Water Purifier](https://katadyn.com/products/sp-mp-efg-katadyn-steripen-classic-3-uv-water-purifier) (spec sheet). Supports: lamp life 8,000 activations, same figure as the SteriPEN Ultra; runs on 4 AA batteries; NiMH 2,300 mAh gives about 100 treatments per set; treats 1 L in 90 seconds or 0.5 L in 48 seconds.
11. [MSR (Cascade Designs), Guardian Purifier](https://cascadedesigns.com/products/guardian-purifier) (spec sheet). Supports: 0.02 micron pore size; meets NSF protocol P248, the US military testing standard, for viruses, bacteria and protozoa; 2.5 L/min flow, self-cleaning pump; cartridge rated for 10,000+ L.
12. [Grayl, GeoPress Purifier Water Bottle](https://grayl.com/products/24oz-geopress-filter-purifier-water-bottle-nature-edition) (spec sheet). Supports: electroadsorptive cartridge plus activated carbon; removes 99.99% viruses, 99.9999% bacteria, 99.9% protozoan cysts; treats 24 oz in 8 seconds; meets EPA Guide Standard; also cites NSF/ANSI 42 and 53.
13. [CDC, Show Me the Science: When & How to Use Hand Sanitizer](https://www.cdc.gov/handwashing/show-me-the-science-hand-sanitizer.html) (regulator). Supports: at least 60% alcohol recommended when soap and water are unavailable; 60 to 95% alcohol is the most effective range; does not reliably inactivate Cryptosporidium, norovirus or C. difficile.
14. [Wikipedia, Hand sanitizer](https://en.wikipedia.org/wiki/Hand_sanitizer) (primer). Supports: 60 to 95% alcohol is the most effective range, CDC-recommended; most products contain 60 to 80% alcohol.
15. [Cleanwaste, The Original WAG BAG](https://cleanwaste.com/product/the-original-wag-bag/) (spec sheet). Supports: gelling, deodorizing powder bag plus a puncture-resistant disposal bag; gels up to 32 ounces of waste.
16. [NEMO Equipment, Helio Pressure Shower](https://www.nemoequipment.com/products/helio-pressure-shower) (spec sheet). Supports: 2.9-gallon tank, foot-pump pressurized; 5 to 7 minutes of continuous spray.