Say you take a bad tumble on the trail and end up with a nasty scrape or cut. Even worse, dirt and debris are ground into the wound. To minimize the risk of infection, you need to thoroughly clean the injury site and get all of that debris out of there, especially if you are deep in the wilderness without ready access to outside medical help.

To do this properly and effectively, you need a special item that many first aid kits neglect to include: an irrigation syringe . This simple, lightweight tool allows you to squirt a stream of water with enough pressure to remove dirt from most wounds. Even better, it’s a tool that weighs almost nothing (under 1 ounce) and costs as little as $0.99 (like this recommended 12cc offering, pictured above, from the NOLS backcountry store).

Irrigation syringes work because of the amount of water pressure they generate, typically somewhere in the range of 20 to 50 psi, which forces potential bacterial contaminants from the wound. To thoroughly clean the wound and minimize the risk of infection, it is recommended that you use copious amounts of treated water (several liters worth) and do so as soon as possible after the injury occurs.

No irrigation syringe? Here are the best backup options

And if you don’t have an irrigation syringe when you need one? A fascinating study from the Wilderness Medical Society—Pressures of Wilderness Improvised Wound Irrigation Techniques: How Do They Compare?—tested these alternatives:

After carefully measuring the pressure generated by each device, the study concluded that two of the common hiking items—a hydration bladder and Ziploc bag (punctured with a 14-gauge needle)—failed to generate sufficiently high pressure to meet the minimum generally recommended for irrigating wounds. (Interestingly, there is currently no consensus in the medical community about the minimum pressure required for effective wound irrigation; the Wilderness Medical Society currently recommends a minimum range of 6 to 15 psi.)

Better were the sports-top water bottle, which could generate pressures up to 6 psi; and the water bottle with 14-gauge needle holes, which generated pressures up to 25 psi. The Sawyer cleaning syringe (akin to this one) also did well, reaching pressures of 7 to 10 psi.

All that being said, the study authors note that another recent, and potentially practice-changing, study found that even very low pressures (1 to 2 psi) can be effective at preventing infection, in which case both the hydration bladder and Ziploc approaches would provide at least some benefits.

So long story short: If you have an open wound in the backcountry, thoroughly clean it out, as soon as possible, with the best available tool you’ve got. And adding an irrigation syringe to your first aid kit is the best way to have the best available tool when you need it most.