How to Choose the Right Running Vest or Hydration Pack

Whether you're heading out for a fast 10km or a full day in the mountains, carrying water, nutrition and essential gear safely and comfortably makes a huge difference to your run. But hydration vests and packs vary enormously - and the right one depends entirely on how far you're going and what you're carrying. Here's how to choose.

Start with capacity, not brand

The biggest factor is volume, and it should match your typical time out on the trail rather than the longest run you might do once a year.

• Under 5L - short runs (under 90 minutes), road running, races where aid stations are frequent. Usually just soft flasks and a phone/gel pocket.
• 5-10L - the sweet spot for most trail runners. Enough room for extra layers, nutrition, a first aid kit and navigation tools, without feeling bulky.
• 10-20L - longer trail days, ultra racing with mandatory gear, or fastpacking overnighters where you need to carry more.
• 20L+ - multi-day fastpacking and lightweight hiking, where you're carrying a sleep system and food alongside water.

If you're regularly moving between short runs and longer mountain days, it's often better to size for your longest common outing and simply carry it lighter on shorter runs, rather than buying two packs.

Bottles vs. bladder - or both

• Soft flasks (front-mounted) are the standard for most running vests. They're easy to refill on the move, keep weight centred on your chest, and let you track intake at a glance.
• Bladders (reservoir + hose) hold more volume and free up front pocket space, but can be harder to refill mid-run and add weight higher up your back.
• Many packs support both - check whether the vest you're looking at has a bladder sleeve as well as front bottle pockets, so you're not locked into one system.

For most day-to-day trail running, two 500ml–600ml soft flasks up front is the most popular and versatile setup.

Fit matters more than features

A vest that moves, bounces or chafes will ruin a run no matter how many pockets it has. When trying one on:

• It should sit close to your body with no bounce when you jog on the spot, fully loaded
• Chest straps should be adjustable enough to fit over different layers (singlet in summer, jacket in winter)
• Check that it doesn't restrict breathing or dig into your collarbone, the back of your neck, or under-arm, especially loaded with bottles
• Try it on with the amount of gear you'd actually carry - an empty vest fits very differently to a loaded one

Vest sizing also varies noticeably between brands, so if possible, try before you buy - sizing charts alone can be unreliable, particularly for women's-specific fits.

Think about what you'll actually carry

Different runs demand different gear, so consider what pockets and attachment points you actually need:

• Front pockets for soft flasks, gels, and a phone
• Zippered security pocket for keys, cards or cash
• Rear main compartment for a spare layer, first aid kit, or emergency shelter
• Pole straps if you're fastpacking or running technical terrain with poles
• Bladder compatibility if you prefer higher-volume hydration
• Race-vest compliance if you're targeting events with mandatory gear lists (check the pack has enough dedicated space to meet requirements without overstuffing)

Don't forget the extras

Whatever vest or pack you land on, a few accessories are worth thinking about from day one:

• Extra soft flasks as spares or for electrolyte mixes separate from plain water
• A bladder if your pack supports one and you want higher capacity for hot days or longer routes
• Poles and pole straps for fastpacking or steep technical terrain
• A reliable fuel source - gels, chews or drink mixes - to fill those front pockets on longer efforts

Our recommendation

For most runners doing regular trail outings in New Zealand's variable conditions, a 5–10L vest with two front soft flasks, a bladder-compatible rear compartment and at least one secure zip pocket covers the vast majority of situations - from a wet Wellington hill loop to a long day on the Tongariro Northern Circuit. If you're planning multi-day fastpacking, step up to a 15–20L pack designed with a proper hip belt for load transfer, rather than trying to stretch a running vest beyond its limits.

Browse our full range of hydration vests, fastpacks and accessories from Salomon, Ultimate Direction and more to find the right fit for your next adventure.