One Flask or Two? A 500 ml Soft Flask for the Trail

Water is one of the first things you pack and one of the things you reach for most often. Where it sits, how you drink from it and what happens to the empty container all shape the way your kit feels on a run or hike.

The new RidgeSong 500 ml Collapsible Soft Flask brings those choices into a small, flexible container. It holds 500 ml, weighs approximately 45 g empty and folds down when the water is gone. Here is how to decide where it belongs in your setup.

Start with the stretch between refills

Before choosing a single flask or a pair, look at your route. Think about the conditions, your own drinking needs and where you can reliably refill. Allow for sections that take longer than expected. A container's capacity is only one part of that plan.

One flask holds 500 ml. Two hold a liter between them. If your planned carry is larger, these flasks can sit alongside another container. Avoid deciding that a particular distance or duration automatically calls for one flask: the route and conditions matter.

For everyday use, a single flask gives you one drink to keep within reach. A pair adds flexibility. You might carry plain drinking water in one and a suitable sports drink in the other, or keep two flasks ready for separate outings.

Choose your pack and colors

Each flask comes complete with its cap and bite-to-drink mouthpiece. The single pack contains one flask; the duo contains two. Both pack sizes use the same 500 ml design.

The options are straightforward:

• One flask in Olive Black or Mist White.
• Two flasks in Olive Black.
• Two flasks in Mist White.
• A mixed pair with one Olive Black and one Mist White.

A mixed pair can help you tell two drinks apart at a glance. Choose matching colors if you prefer them; the capacity and function stay the same.

Check the pocket before the trail

The flask measures approximately 75 × 265 mm. Compare those dimensions with the pocket where you intend to carry it, including room around the neck and mouthpiece. Running-vest pockets vary, so check the fit with your own vest rather than assuming that every pocket will work.

Before setting off, fill the flask and try your intended carry position. Check that you can remove and replace it comfortably and that the pocket holds it securely when you move. Keep it away from sharp gear.

The flexible body folds into a smaller shape when empty. That makes it useful when you want to free up room between refills or tuck an empty spare back into your pack.

A mouthpiece for sipping, a wide opening for filling

The bite-to-drink mouthpiece lets you take a sip without removing the main cap. For refills, the 42 mm opening gives you room to add drinking water or drink mix. Replace the cap securely before putting the flask back into your kit.

If you use a sports drink, make rinsing part of the end-of-outing routine. Empty the remaining liquid and clean the flask before putting it away. A convenient refill opening is most useful when the flask is ready to use again.

Where DualFlow fits

The flask is a water container and does not filter or purify water. It is compatible with the RidgeSong DualFlow Outdoor Water Filter for a separate filtration setup. DualFlow is sold separately from both the single and duo flask packs.

If your route involves untreated water, plan the treatment step as well as the carry capacity. Follow the filter's setup and use instructions, and keep your drinking components separate from untreated water. You can explore the system and its different connections in the DualFlow design story.

Finish the outing with a clean, dry flask

Rinse before first use and after every outing. Use a mild neutral cleaner or a suitable flask-cleaning tablet when needed, then rinse thoroughly and let the flask air-dry completely. Avoid bleach, harsh chemicals, stiff brushes and sharp objects.

Use drinking water or noncorrosive sports drinks. Keep liquids at or below 60°C / 140°F and never fill the flask with boiling water. For storage, leave it dry and loosely arranged, away from heat and direct sunlight. Save tight folding for carrying it during an outing.

Start with the water you need to carry, check where the flask will sit, then choose your color and quantity. Choose your 500 ml Soft Flask for the next route on your list.