Comrades Marathon Hydration Guide 2026

Comrades Marathon Hydration Guide 2026

May 2026

The Ultimate Human Race demands an ultimate hydration plan. Here is how you build yours.

TL;DR:

Question Answer
Race date Sunday, 14 June 2026
Direction Up Run: Durban to Pietermaritzburg
Distance Approximately 87km
Total elevation gain Over 1,800m
Cut-off time 12 hours from gun start
Start time 05h30 at Durban City Hall
Refreshment stations Approximately 40 to 48 stations, roughly every 2.5 to 3.5km
What stations provide Water, Energade, Coke. Second half also has bananas, potatoes, and sweets
Gels at stations No gels provided. You must carry your own
Recommended fluid intake 400 to 800ml per hour, adjusted for conditions
Biggest hydration danger Hyponatremia from drinking too much plain water over 12 hours
Recommended soft flask setup 500ml for water and electrolytes + 250ml for gels

Disclaimer: This guide is for educational and informational purposes only. The hydration and nutrition information provided is based on publicly available sports science research, Comrades Marathon official sources, and experienced runners' accounts. It is not intended as medical, nutritional, or professional sports advice. Individual hydration needs vary significantly based on body weight, sweat rate, fitness level, running pace, health conditions, and weather on race day. Always consult a qualified healthcare professional, registered sports dietitian, or certified coach before making decisions about your race day nutrition and hydration strategy. Do not use this guide as a substitute for professional advice, particularly if you have any underlying health conditions.

What Makes Comrades Different from Every Other Race

The Comrades Marathon is the world's largest and oldest ultramarathon, first run on 24 May 1921 when Vic Clapham, a World War I veteran, created a living memorial to fallen soldiers. The 2026 edition will be the 99th running of the race, and the 50th time the Up Run route from Durban to Pietermaritzburg has been used.

On paper, 87km sounds like a number you can plan around. In practice, Comrades is unlike any other race you have run. The route gains over 1,800m of elevation and is dominated by five major climbs known as the Big Five: Cowies Hill, Fields Hill, Botha's Hill, Inchanga, and Polly Shortts. The Up Run is considered the harder of the two directions because the climbing is front-loaded, meaning the hardest marathon you will ever run comes in the first half before you even reach halfway at Drummond.

Add to this a 12-hour window to finish, June winter conditions in KwaZulu-Natal that can swing from cold darkness at the 05h30 start to warm humid conditions by mid-morning, and the fact that no energy gels are provided at the refreshment stations, and you have a race that rewards careful preparation above everything else.

This guide focuses specifically on hydration. Getting your fluids and electrolytes right will not guarantee a finish, but getting them wrong almost certainly guarantees suffering. Let us break it down.

Understanding the Up Run Route and Why It Changes Everything

Before planning your hydration, you need to understand what the route does to your body zone by zone. The Up Run is not evenly hard, and your hydration needs shift dramatically as the race progresses.

0 to 20km: Durban City to Cowies Hill and Fields Hill

The race starts in the dark on a wide main road outside Durban City Hall and immediately climbs. There is a short flat stretch before Tollgate at 4 to 5km, then 45th Cutting at 6 to 7km, and the climbing continues from that point with very few breaks. Cowies Hill, the first of the Big Five, comes at around 11 to 17km and rises approximately 100 metres. Fields Hill, the longest of the Big Five at roughly 3km, follows shortly after.

This section is run in cool to cold conditions, typically 11 to 12°C at the Durban start. Your sweat rate will be lower in the dark and cold, but do not use this as an excuse to skip early hydration. Starting your electrolyte intake from the first 10km matters more than most runners realise, because the deficit compounds over 12 hours.

Hydration focus: Sip steadily, start electrolytes early, do not drink aggressively in the dark.

20 to 44km: Through Botha's Hill to Halfway at Drummond

According to nine-time Comrades winner Bruce Fordyce, the first half of the Up Run is the hardest 42km many runners will ever run. After Fields Hill and Cowies, Botha's Hill arrives in this section before the route undulates through Gillits and toward Drummond, the traditional halfway point. By now the sun is up and temperatures are rising. This is where sweat rate begins to climb meaningfully and where many runners make the critical mistake of drinking too much plain water at stations without balancing it with sodium.

The half marathon mark is not a relief point at Comrades. It is where the race begins to test your preparation.

Hydration focus: Increase fluid intake as temperature rises. Prioritise electrolytes at every station.

44 to 60km: Inchanga and the Harrison Flats

Inchanga, the fourth of the Big Five, is a long winding climb that arrives just after halfway and delivers spectacular views of the Valley of a Thousand Hills. After Inchanga the route descends and then rolls through the Harrison Flats, a section that feels flatter than the rest of the course but is still undulating and mentally taxing. The highest point on the entire course is at Umlaas Road, around 870m above sea level.

By this point most runners have been on their feet for 5 to 7 hours. Dehydration risk is real. So is hyponatremia from runners who have been drinking large volumes of plain water since Durban without adequate sodium. Keep your intake consistent rather than compensating with large volumes at one station.

Hydration focus: Consistent small sips. Alternate water with Energade. Use Coke strategically for a caffeine boost.

60 to 87km: Cato Ridge, Camperdown, and Polly Shortts

The final third of the Up Run is where Comrades earns its reputation. From Cato Ridge through Camperdown, the route continues to roll before delivering Polly Shortts, the last and most famous of the Big Five, at around 78 to 80km. Bruce Fordyce describes it as having a few deceptive twists and turns with a long central spine of solid climbing. It is steep, it comes when fatigue is at its peak, and it is where most runners walk regardless of their medal target.

After Polly Shortts, the final descent into Pietermaritzburg awaits with a few more smaller climbs. Do not ease off on fluid intake just because you can sense the finish.

Hydration focus: Small sips through Polly Shortts. Keep drinking to the finish line.

The key insight: Comrades is a race of two halves, and the second half is nothing like the first. Consistent hydration throughout the day is the strategy. There is no catching up a deficit at 70km.

What the Refreshment Stations Actually Provide

The Comrades refreshment stations are positioned approximately every 2.5 to 3.5km along the route, with approximately 40 to 48 stations in total staffed by close to 5,000 volunteers.

What you will find at stations:

  • Water: Provided throughout the race in sachets
  • Energade: Sports drink available at most stations
  • Coke: Available throughout, useful for caffeine boost in later stages
  • Bananas, potatoes, and sweets: Available at some stations in the second half of the race

The critical fact that surprises first-timers: There are no energy gels provided at Comrades refreshment stations. If you rely on gels during races, you must carry your own supply for the entire 87km. This is one of the most important logistical differences between Comrades and shorter road races.

The stations are well-stocked and the support is excellent, but carrying your own preferred electrolyte tabs or sachets gives you control over your sodium intake rather than depending entirely on Energade at each station.

How Much Should You Drink? The Science Behind the Numbers

Research published by the American College of Sports Medicine recommends 400 to 800ml of fluid per hour during endurance exercise, adjusted for conditions and individual sweat rate. For an event lasting 7 to 12 hours, this guidance needs to be applied carefully.

Sweat rate varies between 0.5 and 2.0 litres per hour among runners, with many factors including body size, pace, temperature, and humidity all playing a role. The best way to know your personal number is through a sweat rate test:

  1. Weigh yourself in kg before a 1-hour run
  2. Run at race effort without drinking
  3. Weigh yourself after
  4. Every kg of weight lost equals approximately 1 litre of sweat lost

For Comrades specifically, adjust your intake based on the conditions of the day:

  • Cool morning start (05h30, around 11 to 15°C): 400 to 500ml per hour
  • Warming mid-race conditions (by 9am, 18 to 22°C): 500 to 650ml per hour
  • Warm to hot afternoon conditions for slower runners (above 22°C): 600 to 800ml per hour

The Comrades refreshment stations every 2.5 to 3.5km make it practical to drink consistently without carrying large volumes. At most paces, drinking 150 to 200ml at each station keeps you in range. The key is consistency throughout the day, not catching up in large volumes after a long dry stretch.

Practical rule: Drink to thirst but do not wait until you feel very thirsty. By the time you are very thirsty, you are already behind. Check your urine at toilet stops. Pale yellow is good. Orange means drink more. Completely clear with no yellow means you may be overdrinking.

Electrolytes: The Part That Can Save or Sink Your Race

Over 7 to 12 hours of running, electrolyte management is not optional. It is the difference between finishing well and finishing in the medical tent.

Why hyponatremia is the bigger danger at Comrades

Most runners are warned about dehydration, but at an event lasting as long as Comrades, hyponatremia, which is dangerously low blood sodium caused by drinking too much plain water without adequate sodium replacement, is a genuine medical risk. The symptoms, including nausea, headache, confusion, and swelling in the hands or face, look similar to dehydration, which is why runners sometimes respond by drinking more plain water and making the condition worse.

The greatest predictor of hyponatremia is weight gain during the race, meaning you have consumed more fluid than you have lost. Slower runners who spend more time on course and who drink at every single station regardless of thirst are at higher risk.

The solution is straightforward: combine your fluid intake with consistent sodium replacement.

Electrolyte targets for Comrades

  • Sodium: 300 to 600mg per hour as a general guideline, increasing toward the higher end in heat or if you are a heavy sweater
  • Potassium: 150 to 250mg per hour
  • Magnesium: Useful for muscle function and cramp prevention over a long day

Sources of electrolytes during the race:

  • Electrolyte tabs or sachets mixed into your soft flask water (most controllable option)
  • Energade at stations (convenient but variable)
  • Coke at stations (useful for caffeine and sugar, minimal electrolytes)
  • Salty foods at stations in the second half, particularly the potatoes which many runners swear by
  • Salt capsules or salt tabs carried in your vest pocket

Your Soft Flask Setup for Comrades

The combination of long distance, no gels at stations, and the need to carry your own nutrition makes Comrades a race where carrying your own soft flask setup is genuinely advantageous.

The 500ml OG SoftFlask: Your Primary Hydration

Fill with water and your electrolyte mix of choice. With stations every 2.5 to 3.5km, you can manage comfortably on a 500ml flask and refill at stations when needed. Carrying your own electrolyte water means you control your sodium intake rather than depending entirely on whatever sports drink each station is providing.

  • Best for: Water with electrolyte mix between stations
  • Carry in: Vest front pocket or running belt
  • Refill strategy: At each station or every second station depending on your pace and conditions

The 250ml Mini T SoftFlask: Your Gel Carrier

Since Comrades provides no gels, this is arguably more important here than at any other SA race. Mix 5 to 6 energy gels with 20 to 30ml of water, shake to combine, and carry as your personal nutrition supply. Sip steadily throughout rather than taking one full gel every 30 minutes. This delivers steadier energy without the blood sugar peaks and crashes that become problematic over a 12-hour effort.

  • Best for: Pre-mixed gel storage for the full race
  • Holds: 5 to 6 standard gels, enough fuel for approximately 2.5 to 3 hours of running
  • You may want to refill at a support point if you have one arranged

A note on hydration packs and vests

Running Comrades with a hydration vest or pack is a viable option, particularly for runners coming from a trail running background where carrying gear is standard practice. The stations are well-supported enough that most runners do not feel they need a full vest for water capacity. However, a running vest with soft flask pockets gives you the two-flask setup (500ml hydration plus 250ml gels) without adding significant weight. Many experienced Comrades runners use a lightweight vest for exactly this reason.

Pre-Race Hydration: The 48 Hours Before

What you do before the race matters enormously for an event of this length.

Friday and Saturday: Building your reserves

  • Drink consistently throughout both days without forcing large volumes at once
  • Include electrolytes in your fluids, a sports drink or electrolyte tab in water works well
  • Avoid alcohol on both nights
  • Urine should be pale yellow throughout the weekend as your hydration marker
  • Eat normally, do not dramatically change your diet in the final 48 hours

Saturday night

  • Eat a familiar pre-race meal, not too heavy
  • Do not overhydrate in the evening, running to the toilet all night before a 05h30 start is the last thing you need
  • Set out your kit, charge your watch, and prioritise sleep

Race morning

  • Wake up well before the start to allow time for breakfast, hydration, and toilet
  • Drink 400 to 500ml of water with electrolytes when you wake up
  • Take a final small sip of around 150 to 200ml in the 20 to 30 minutes before the gun
  • Do not drink large volumes of plain water in the final hour before the start

Phase-by-Phase Race Day Hydration Plan

Phase 1: 0 to 21km (Durban to Halfway Mark): Patience Above Everything

This is the hardest 21km you will ever run. The discipline here is not to overcook the effort or the hydration.

  • Drink 150 to 200ml at every second or third station in cool conditions
  • Begin electrolyte intake from the first hour
  • Start your gel intake at 45 to 60 minutes, before you feel you need it
  • Resist the temptation to drink heavily in the dark and cold just because stations are available

The runners who go out too hard and drink too much in the first half are the ones walking from Inchanga onwards. Patience in Phase 1 buys you legs in Phase 4.

Phase 2: 21 to 44km (Halfway): Managing the Climb

  • Increase fluid intake as temperature and effort rise
  • Drink at every station through Botha's Hill and toward Drummond
  • Take electrolytes consistently every 30 to 45 minutes
  • Keep consuming gels on schedule regardless of how you feel
  • Use Energade over plain water where available to maintain sodium intake

Phase 3: 44 to 70km (Inchanga to Cato Ridge): The Long Middle

  • Continue steady sipping through Inchanga and the Harrison Flats
  • Use Coke at stations for a caffeine boost if you need a lift, but pair each cup of Coke with a cup of water
  • Keep electrolyte intake consistent, this is where many runners fall behind on sodium
  • Eat real food at stations if your stomach tolerates it: bananas, potatoes with salt

Phase 4: 70 to 87km (Polly Shortts to the Finish): Fight Through

  • Small sips every 5 minutes through Polly Shortts
  • Do not stop drinking just because you can see Pietermaritzburg
  • Finish any remaining gels before 80km
  • Continue drinking all the way to the finish line

Warning Signs to Know

Signs of Dehydration

  • Urine that is dark orange or brown, or inability to urinate for 2 or more hours
  • Excessive thirst, dry mouth, dizziness
  • Muscle cramps that worsen despite movement and stretching
  • Feeling significantly hotter than you expect for the conditions

If dehydration signs appear: walk to the next station, drink water with Energade, eat something salty, ease your pace, and consider alerting a race medic.

Signs of Hyponatremia (Overhydration)

  • Nausea, headache, or swelling in hands, face, or wrists
  • Confusion or feeling mentally foggy despite no obvious pain
  • Bloating or feeling sloshy despite not having drunk recently
  • Weight gain during the race (if you have a way to check)

Hyponatremia is a more serious risk at ultra events than most runners realise, particularly among slower runners who spend the most time on course. If you suspect hyponatremia, stop drinking plain water immediately. Take in sodium through salt capsules, potatoes, or Energade. Alert a race medic. Do not attempt to run through it.

June Weather in KwaZulu-Natal: What to Expect

Comrades takes place in the South African winter, and June in KZN means a wide range of possible conditions. The start in Durban is relatively mild, typically around 11 to 12°C at 05h30. As the race progresses and the field climbs into the Valley of a Thousand Hills, conditions can warm significantly by mid-morning.

The 2025 Comrades was described as warm and humid. Previous years have brought everything from ideal cool conditions to cold fronts, strong winds, and unexpected rain later in the day. The South African Weather Service typically issues race-specific forecasts in the week before the event, which are worth monitoring closely.

Practical preparation for variable conditions:

  • Start with a light throwaway layer you can discard in the early kilometres
  • Carry sunscreen in your vest for when the sun comes up
  • In wind, increase your fluid intake even if you do not feel hot, wind accelerates fluid loss
  • If conditions are hotter than expected, increase your intake toward the higher end of the range

Post-Race Recovery Hydration

Crossing the finish line in Pietermaritzburg is one of the great moments in South African sport. But your body still needs attention.

  • Drink 500ml of water or electrolyte drink within 30 minutes of finishing
  • Eat something salty as soon as you can manage it
  • Continue drinking steadily over the next 3 to 4 hours
  • Monitor urine colour as a guide to recovery
  • If you feel nauseous or confused after finishing, alert medical staff immediately rather than trying to recover on your own

After that, you have absolutely earned the celebration.

Quick Race Day Soft Flask Checklist

  1. Fill your 500ml flask with water and your electrolyte mix the night before
  2. Fill your 250ml flask with 5 to 6 gels mixed with 20 to 30ml of water
  3. Shake both flasks and pack them in your vest or belt
  4. Pack spare electrolyte tabs in your vest pocket
  5. Pack salt capsules as a backup for cramp prevention
  6. Know roughly where the major stations are (every 2.5 to 3.5km) and plan refills
  7. Start sipping within the first 20 minutes before you feel thirsty
  8. Never use gear on race day you have not trained with

A Note from SoftFlask

Comrades is unlike anything else in South African running. The atmosphere at the Durban start in the dark, the rooster crow, Shosholoza, the crowd at Drummond, and the view from Inchanga are things that stay with runners for life.

But it is also an event that has humbled countless prepared runners who did not treat hydration seriously enough. Twelve hours is a long time to manage your body. Drink steadily. Take electrolytes consistently. Carry your own gels because the stations will not provide them. And respect the route, particularly the first half, which will try very hard to get you to go too fast and drink too much too soon.

Ska Fela Moya. Don't Give Up.

Gear Mentioned in This Guide

OG SoftFlask (500ml): Your primary hydration flask for Comrades. Fits all major running vests and belts, collapses as you drink, BPA-free TPU construction. Shop the OG SoftFlask

T1 SoftFlask (500ml): The large-cap version for easy electrolyte powder and ice access on warm race days. Shop the T1 SoftFlask

Mini T SoftFlask (250ml): Your gel carrier. Holds 5 to 6 gels pre-mixed with water for mess-free nutrition over 87km. Critical at Comrades since no gels are provided at stations. Shop the Mini T SoftFlask

Related Guides

If you are also running Two Oceans in April before Comrades in June, our Two Oceans Marathon Hydration Guide 2026 covers the same format for the 56km route.

For the science behind how much to drink and when, our evidence-based hydration guide for runners goes deeper on sweat rate testing and electrolyte timing.

If you are still deciding on your flask size or carrying setup, our 250ml vs 500ml soft flask guide breaks down every scenario.

Not sure how to carry your gels without the mess? Our guide on how to carry energy gels on long runs covers the gel flask method in detail.

Sources and References

All information in this guide is drawn from verified race sources and published sports science research.

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