HydraPak SoftFlask Collapsible Bottles

HydraPak SoftFlask bottles come in small sizes to accommodate energy gels or liquids. Made of soft thermoplastic polyurethane (TPU), the collapsible, flexible material is remarkably strong and resistant to abrasion, even when abused on the backpacking trail. The company states that if used for gels, the 150 ml flask can hold five servings and the 250 ml flask can hold eight servings.

Blue collapsible bottle held up in front of a creek

HydraPak SoftFlask 250 ml bottle with electrolyte mix on a short hike at Hood Mountain Regional Park.

I was interested in the soft bottles for a purpose for which they are not intended, which is to hold small amounts of olive oil or drink powders. It’s easy to find a variety of bottles in the 0.5 and 1 liter sizes, but smaller collapsible bottles are not prevalent. I’ve tested the HydraPak bottles on three backpacking trips in Sonoma and the Sierra and have been impressed with their strength and flexibility.

HydraPak SoftFlask 150 ml bottle with olive oil

I’ve been using the 150 ml bottle to hold olive oil. I use the olive oil to supplement my freeze-dried dinners to add calories and flavor. The last thing any backpacker wants is an olive oil explosion all over the inside of their pack. Therefore, I thought it prudent to store the bottle in a snack size zip-top baggie. The nozzle twists open and closed but since I wasn’t drinking directly from the bottle, I chose to unscrew the cap to pour out a portion of olive oil. As long as the nozzle was twisted shut, the bottle did not leak. On one overnight trip the olive oil did leak but I noted that the nozzle had been left in the open position. I was leading a backpacking trip and shared some olive oil with the group. I believe one of the participants opened the nozzle to squirt the olive oil and didn’t get the nozzle completely closed so I have to chalk that one up to user error. I usually use one tablespoon of olive oil at a time so the 150 ml flask would hold about 10 servings. On a thru hike I could see using a couple of these for different kinds of fluids or suspensions such as soy sauce, lemon oil, salad dressing or ketchup.

Funnel set in flask to pour Tang orange drink powder

Loading the Softflask with Tang orange drink powder (no water)

I also wanted to test the use of drink powders, such as Tang. I like to store the powders in a collapsible container so it will shrink as the trip progresses. I’m talking about just storing the powder without an added liquid. I have some 0.5 and 1 liter collapsible bottles but I have been looking for some smaller bottles for shorter trips. I used a 150 ml SoftFlask to store Tang orange drink power, again eschewing the use of the nozzle. In camp, I twisted the cap off and poured approximately 2.5 teaspoons of orange crystals into a cup, then added 8 oz. of water. It worked fine but I noticed that within a few days, the powder started clumping and looked moist, despite no water being added. This was a less successful test due to the clumping but again, this was not the intended purpose for this flask.

Funnel set in flask to pour drink powder

Loading the SoftFlask with Skratch electrolyte powder

The 250 ml bottle has the same shape as the 150 ml bottle but has a high-flow bite valve that auto-seals after each sip. This slightly larger size was useful for carrying an electrolyte mix. On long trips, I carry a hydration bladder plus a one-liter bottle of water with a dilute electrolyte powder. Sometimes that is too much volume for an easy overnight trip. The 250 ml SoftFlask was ideal for carrying a smaller amount of electrolyte mix for a day hike or one-night trip.

Overall, the HydraPak SoftFlask bottles fill a niche for small volume collapsible bottles that are useful for carrying liquids. They also make larger collapsible bottles and cups.

750 and 1000 ml HydraPak Stash flexible bottles


HydraPak SoftFlask 150 ml bottle

Available at HydraPak for around $13

Capacity: 150 ml / 5 fl oz
Weight: 18 g / 0.6 oz
Dimensions: 165 mm / 6.5 in x 71 mm / 2.8 in
Material: Thermoplastic Polyurethane; HDPE (BPA & PVC-free)

HydraPak SoftFlask 250 ml bottle

Available at HydraPak or Amazon for around $14

Capacity: 250 ml / 8.5 fl oz
Weight: 23 g / 0.8 oz
Dimensions: 222 mm / 8.7 in x 71 mm / 2.8 in
Material: Thermoplastic Polyurethane; Silicone; HDPE (BPA & PVC-free)

HydraPak Stash 750 and 1000 ml flexible bottles

Available at HydraPak and Amazon for around $22


The HydraPak SoftFlasks can be used for a variety of oils, gels and drink powders

Disclosure of material connection: I received a sample for testing purposes, but the opinions expressed are solely my own.