Potable Aqua + PA Plus review

What it is and who it suits

Potable Aqua is an iodine tablet system. The maker lists tetraglycine hydroperiodide as the active ingredient and describes the tablets as for use only when drinking water is of questionable quality, not on a continuous basis. PA Plus is a separate ascorbic acid (vitamin C) tablet, 45 milligrams each, that neutralizes the residual iodine afterward.

It suits a go-bag, glovebox or hiking kit where a few ounces of backup treatment matter more than a filter. This review is researched, not tested. It relies on the maker's product page, EPA's emergency disinfection page and CDC's water disinfection guidance for travelers.

How the two steps work

The maker's directions are to add 2 Potable Aqua tablets to 1 quart or liter of water, cap loosely, wait 5 minutes, shake so the threads are wet, tighten the cap and wait 30 minutes. The page advertises the water as ready in 35 minutes. PA Plus comes after that: wait at least 30 minutes, add 2 PA Plus tablets per quart, shake and wait 3 minutes. The tablets need not dissolve completely.

The order matters. The maker says never to add PA Plus at the same time, because the iodine would be converted to a form that cannot disinfect. It also says PA Plus is optional, and that once it is added the water no longer has residual iodine protecting it, so the maker suggests saving it for just before you drink. At the label dose, a 50-tablet bottle treats about 25 quarts, so compare any listing's quarts-per-bottle claim with the label.

What EPA and CDC add

EPA lists disinfection tablets containing chlorine, iodine, chlorine dioxide or other agents as an option and says to follow the product label because strengths differ. It says disinfection works less well in cloudy or colored water, so let water settle and filter it through a clean cloth, paper towel or coffee filter first. EPA also says boiling or disinfection will not remove heavy metals, salts or most other chemicals.

EPA's preferred method is a rolling boil of at least one minute, or three minutes above 5,000 feet. For more on choosing a method, see our make water safe guide and boil water advisory guide.

The limits of iodine

CDC's traveler guidance says not to drink iodine-disinfected water if you are pregnant, have thyroid problems or have a known iodine hypersensitivity, and not to use it for more than a few weeks at a time. The maker's page tells readers to read the full label, and does not repeat those points, so check the bottle.

CDC also says disinfectants kill most viruses and bacteria but are not as effective against resistant organisms such as Cryptosporidium and Giardia, and that chlorine dioxide tablets can be effective against Cryptosporidium if used as directed. The maker says the tablets are proven against Giardia lamblia when used as directed and does not make a Cryptosporidium claim on its page. If the water may be chemically contaminated, no tablet makes it drinkable.

How it compares with the other picks

The other picks on our water purification tablet comparison include Aquatabs, which are chlorine-based rather than iodine-based and have their own review of the 49 mg pack, plus a plain Potable Aqua bottle without the neutralizer. The practical difference is the fix for taste: PA Plus adds a step and a wait but removes iodine's flavor. Chlorine tablets avoid the iodine cautions above. Keep a larger water store from the how much water to store guide so tablets stay a backup.

Verdict and who should skip it

A reasonable backup if you can follow a timed two-step routine and iodine suits everyone who will drink the water. Skip it if anyone is pregnant or has a thyroid condition, if you expect to rely on it beyond a few weeks, if you worry about Cryptosporidium, or if you want a single-step tablet.

How long do Potable Aqua tablets take to work?

The maker says 2 tablets per quart or liter, loosely capped for 5 minutes, then 30 minutes in total. Add PA Plus only after at least 30 minutes, then wait 3 more minutes before drinking.

Can I add PA Plus at the same time?

No. The maker says adding PA Plus with the Potable Aqua tablets converts the iodine to a form that cannot disinfect the water. Wait at least 30 minutes first.

Is iodine safe for everyone?

No. CDC says people who are pregnant, have thyroid problems or are hypersensitive to iodine should not drink iodine-disinfected water, and nobody should for more than a few weeks at a time.

Do these tablets handle Cryptosporidium?

CDC says disinfectants are not as effective against Cryptosporidium and Giardia, and that chlorine dioxide tablets can work if used as directed. Boiling is EPA's first choice when you can.