Something nasty has leaked into The Outlast Trials, and this time, simply surviving the Trial isn’t the only thing you need to worry about.

The Chemical Leak limited-time event is now live as part of the Season 7.1 update, bringing toxic gas hazards, valve-based objectives, event-specific Tasks, Chemical Leak Event Tokens, and a limited-time Catalog packed with exclusive rewards.

The event runs for roughly four weeks, from September 8, 2026, at 10:00 AM ET, until October 6, 2026, at 10:00 AM ET. During this window, you can earn Event Tokens from regular Trials and MK-Challenges, while the dedicated Special Therapy: Chemical Leak activities throw you directly into the event’s toxic-gas mechanics.

And there’s one deadline you absolutely don’t want to forget: unused Event Tokens are forfeited when the event ends.

So, if you’re jumping into The Outlast Trials for this event, here’s everything you need to know about earning Tokens, farming them efficiently, finding and shutting off valves, completing Chemical Leak Tasks, and surviving those contaminated areas without turning yourself into dinner.

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The Outlast Trials Chemical Leak Event Dates

The Chemical Leak event is available for roughly four weeks.

• Start: September 8, 2026, at 10:00 AM ET
• End: October 6, 2026, at 10:00 AM ET
• Event Catalog: Available throughout the event
• Event Tokens: Must be spent before the event ends
• Unused Tokens: Forfeited when the event concludes

The event is part of Season 7.1, which also introduces two new MK-Challenges: Change the Program and Fund the Campaign.

That means there’s plenty to do beyond simply grinding the event activities.

How to Earn Chemical Leak Event Tokens

Here’s the good news: you aren’t forced to play only the Chemical Leak Special Therapy activities to earn Event Tokens.

Any MK-Challenge or Trial can reward Event Tokens, with the amount depending on the difficulty.

Difficulty	MK-Challenge Tokens	Trial Tokens
Introductory	+3	+6
Standard	+3	+6
Intensive	+6	+9
Psychosurgery	+9	+12

These are the currently reported Chemical Leak Event Token payouts, and higher difficulties clearly offer better rewards.

But there’s an important distinction between maximum Tokens per completion and best farming efficiency.

A higher payout doesn’t automatically mean a better farm if the activity takes dramatically longer or you’re struggling to finish it consistently.

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What Is the Fastest Way to Farm Event Tokens?

If your only goal is to stack Event Tokens quickly, MK-Challenges can be more efficient than full Trials when you can complete them quickly.

The current event guide information specifically highlights Eliminate the Past as a particularly fast MK-Challenge, with runs potentially taking less than 10 minutes.

A full Trial can take considerably longer, so a short, repeatable MK-Challenge may produce better overall efficiency even if its Token payout isn’t the highest possible.

Your approach should therefore depend on what you’re trying to optimize:

• Fast individual runs: Use short MK-Challenges.
• Higher token payout per completion: Play higher-difficulty Trials.
• Efficient farming: Choose the highest difficulty you can complete quickly and consistently.
• Event Tasks: Play the dedicated Chemical Leak activities when you need to progress their Tasks.

In other words, don’t automatically chase the biggest number on the payout screen. The best farm is the one you can clear reliably without turning every run into a survival nightmare.

Special Therapy: Chemical Leak Explained

Want to experience the event’s unique mechanics directly? Head over to the Terminal and check the Special Therapy: Chemical Leak section.

The event-specific lineup contains nine activities:

• 3 Trials
• 6 MK-Challenges

These activities matter for more than just the atmosphere. The dedicated Chemical Leak Tasks are tied to this Special Therapy selection, and completing those Tasks provides additional Event Tokens and rewards beyond the normal completion payouts.

There’s also a rotation to keep track of.

The Special Therapy lineup is reported to rotate every Tuesday at 10:00 AM ET, giving players a new selection of event activities to tackle each week.

So, if you’re trying to complete every available Chemical Leak Task, don’t just keep replaying your favorite Trial. Check the Special Therapy tab regularly and make sure you’re working through the current event activities.

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How the Chemical Leak Mechanics Work

This is where things get spicy.

The Chemical Leak event introduces two special variators that work together to create the event’s main hazard:

Chemical Leak

The Chemical Leak variator fills sections of the Trial with toxic gas.

When an area becomes contaminated, you need to locate the valves responsible for the leak and shut them down so the affected area becomes safe to traverse.

Shut Off the Valves

The second variator makes valve interactions the central mechanic.

You need to find the appropriate valve and turn it off to stop the chemical leak affecting that particular area.

Together, these two variators transform sections of a Trial into hazardous zones where staying too long can become extremely dangerous.

And yes, the game gives you a way out—but you need to find it.

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How the Chemical Meter Works

When you enter an area affected by toxic gas, your Chemical meter starts building.

The longer you remain inside the contaminated area, the more dangerous things become. Once the meter fills, you begin taking progressively more damage.

That creates a very simple survival loop:

Enter contaminated area → locate the leak → find its valve → shut off the valve → clear the gas → continue the Trial.

The important takeaway is that you shouldn’t treat the toxic gas like something you can simply tank forever.

If you’re inside a contaminated section, the safest solution is to find the valve and shut it down.

How to Find Chemical Leak Valves

Getting lost inside toxic gas is obviously not ideal, but the event gives you a major clue.

Listen.

When you’re inside an affected area, listen carefully for the hissing sound associated with the leak.

That audio cue can guide you toward the valve responsible for the gas. Instead of wandering around randomly while your Chemical meter climbs, use the sound to track down the source.

Once you find the valve:

1. Approach the valve.
2. Interact with it.
3. Turn the valve all the way to the left.
4. Once it is shut off, the toxic gas in that specific area is disabled.
5. Continue with the Trial objective.

The valve isn’t some optional little interaction sitting in the corner. In a contaminated section, it is effectively your ticket to making that area safe again.

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Be Careful When Turning Off Valves

There’s a nasty catch.

Turning a valve makes noise.

That means you shouldn’t sprint toward a valve and immediately start interacting with it without checking what’s happening around you.

If an Ex-Pop or Prime Asset is nearby, the noise from the interaction could make an already dangerous situation even worse.

Before you turn the valve:

• Listen for the valve from a relatively safe position.
• Check nearby corridors and rooms.
• Look for nearby enemies.
• Make sure you aren’t about to attract an enemy.
• Shut the valve down quickly once it’s safe to do so.
• Leave the area after the gas clears.

The valve interaction itself isn’t necessarily the dangerous part. The problem is that its noise can create a new problem if an enemy is already close.

Playing With a Team?

This mechanic becomes much easier to manage in multiplayer.

One Reagent can keep watch while another handles the valve.

Having someone cover the area while the other player interacts with the valve can make the entire process considerably safer.

Does Every Valve Clear the Entire Trial?

No.

This is an important detail because the valve system is based around individual affected areas.

When you shut down a valve, you clear the toxic gas associated with that particular section. It does not simply remove the Chemical Leak effect from the entire Trial.

That means larger Trials can require you to locate and shut down multiple valves.

So don’t find one valve, shut it off, and assume you’re completely done with the gas mechanic.

If another section becomes contaminated, you’ll need to deal with its valve as well.

This is another reason why sound awareness matters so much during Chemical Leak activities.

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Chemical Leak Event Catalog and Rewards

All those Event Tokens you’re earning have somewhere to go.

The Chemical Leak event features a limited-time Event Catalog, where you can spend your accumulated Event Tokens on the available rewards.

But don’t make the mistake of treating these Tokens like permanent currency.

The Catalog is temporary.

Once the Chemical Leak event ends:

• The Chemical Leak Catalog is removed.
• Unused Event Tokens are forfeited.
• You can no longer spend those Tokens after the deadline.

So there is no advantage to hoarding Tokens until the final day.

If you’ve earned enough Tokens for something you want from the Catalog, spend them during the event.

Your final deadline is:

October 6, 2026, at 10:00 AM ET.

After that, any unused Event Tokens are gone.

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Best Chemical Leak Event Strategy

Your best strategy depends on what you’re trying to get out of the event.

For Fast Token Farming

Run short MK-Challenges that you can complete consistently.

The activity with the largest theoretical payout isn’t automatically the best farm. If a run takes significantly longer or you’re frequently struggling to finish it, its larger reward may not translate into better efficiency.

Short, reliable runs can be much more practical.

The currently highlighted example is Eliminate the Past, which can potentially be completed in less than 10 minutes.

For Maximum Tokens Per Run

If you’re focused on the biggest payout per completion, higher difficulties are the way to go.

• Intensive: 6 Tokens for an MK-Challenge and 9 Tokens for a Trial.
• Psychosurgery: 9 Tokens for an MK-Challenge and 12 Tokens for a Trial.

However, don’t automatically jump to Psychosurgery just because it offers the highest listed reward.

The key is to choose the highest difficulty you can reliably complete.

A difficult run that takes dramatically longer—or ends in failure—can wipe out the efficiency advantage of its higher payout.

For Chemical Leak Tasks

Head to the Special Therapy: Chemical Leak tab.

Regular Trials and MK-Challenges can still give you Event Tokens, but the dedicated Chemical Leak activities are the important destination when you’re trying to complete the event-specific Tasks.

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For Safer Valve Interactions

Don’t blindly chase the hissing sound.

Instead:

1. Identify the contaminated area.
2. Listen for the valve.
3. Check for nearby enemies.
4. Approach when the area is relatively safe.
5. Shut the valve down.
6. Move out once the gas clears.

The noise created by the valve interaction is the biggest reason to avoid interacting with one while enemies are nearby.

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Chemical Leak Event Tips You Should Know

1. Don’t Ignore the Hissing

The audio cue is one of your most useful tools during the event.

If you’re trapped in a gas-filled room, don’t waste precious time wandering randomly. Listen for the hissing and use it to help locate the valve.

2. Don’t Waste Health on Toxic Gas

The Chemical meter isn’t there for decoration.

If you know where the valve is, prioritize reaching it rather than standing around until the meter becomes dangerous.

The longer you remain in contaminated gas, the more dangerous it becomes.

3. Check for Enemies Before Turning a Valve

Valve interactions create noise.

If an enemy is nearby, that noise can turn a straightforward interaction into a chase.

Take a second to check your surroundings before committing.

4. Use Teammates to Cover Valve Interactions

Playing with a squad?

Use it to your advantage.

Have one Reagent watch the surrounding area while another handles the valve. It makes the interaction considerably safer.

5. Farm According to Your Skill Level

Psychosurgery offers the best listed token payout, but that doesn’t automatically make it the most efficient farming option.

If you’re struggling to finish it or taking far longer than expected, a faster and more reliable activity may be the better choice.

6. Spend Tokens Before October 6

This is the event rule you absolutely cannot forget.

Unused Event Tokens disappear when the Chemical Leak event ends.

Make sure you spend them before October 6, 2026, at 10:00 AM ET.

What Else Was Added in The Outlast Trials Season 7.1?

Chemical Leak is only one part of the Season 7.1 update.

Red Barrels has also added two new MK-Challenges:

• Change the Program
• Fund the Campaign

Season 7.1 also brings changes to Invasion and Escalation, online stability improvements, loadout visibility in the Pause Menu, changes to Rebirth loadouts, balance adjustments, and numerous fixes.

There’s another significant change for players who used mods.

Official Mod Support Has Been Removed

Season 7.1 removes official mod support.

However, Red Barrels says several quality-of-life options that were previously available through mods have now been added directly to the game.

These include:

• Field of View
• Camera Shake
• Motion Blur
• Film Grain
• Chromatic Aberration
• Lens Flares
• Vignette
• Bloom
• Startup Videos
• HUD display options

So while official mod support is being removed, several of the quality-of-life customization options players previously accessed through mods are now available natively.

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Is The Outlast Trials Chemical Leak Event Worth Playing?

If you’re already playing The Outlast Trials during Season 7.1, the Chemical Leak event is definitely worth jumping into.

One of its biggest advantages is that you’re not forced to spend all your time inside the Special Therapy activities just to earn Event Tokens.

Regular Trials and MK-Challenges also generate Tokens.

The dedicated Chemical Leak activities are particularly important when you’re trying to complete the event-specific Tasks and experience the new toxic-gas gameplay built around the Chemical Leak and Shut Off the Valves variators.

The event also gives you a new reason to approach familiar Trial spaces differently. Suddenly, a room isn’t just a room—it could be contaminated, your Chemical meter could start climbing, and somewhere nearby there’s a valve you desperately need to locate.

And when you finally hear that hiss?

That’s your signal to start hunting.

Just remember that the event has a hard deadline.

You have until October 6, 2026, at 10:00 AM ET to spend your Event Tokens. Once the event ends, the Chemical Leak Catalog disappears and any unused Tokens are forfeited.

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The Outlast Trials Chemical Leak Event Quick Checklist

If you just want the essentials before jumping back into the Trials, keep this checklist handy:

• Play Trials or MK-Challenges to earn Chemical Leak Event Tokens.
• Higher difficulties provide larger Token payouts.
• Use the Special Therapy: Chemical Leak tab for event-specific Tasks.
• The Special Therapy lineup contains 3 Trials and 6 MK-Challenges.
• The lineup is reported to rotate on Tuesdays at 10:00 AM ET.
• Listen for hissing sounds when toxic gas fills an area.
• Follow the sound to locate the responsible valve.
• Turn the valve all the way to the left.
• Shutting a valve clears the gas from its specific affected area, not the entire Trial.
• Larger Trials may require you to shut off multiple valves.
• Remember that turning a valve creates noise.
• Check for Ex-Pop and Prime Assets before interacting.
• In multiplayer, have one Reagent cover the area while another handles the valve.
• Use short MK-Challenges for fast farming when they can be completed consistently.
• Intensive: 6 MK-Challenge Tokens / 9 Trial Tokens.
• Psychosurgery: 9 MK-Challenge Tokens / 12 Trial Tokens.
• Spend Event Tokens in the Chemical Leak Catalog during the event.
• Unused Tokens are forfeited after the event ends.
• Final deadline: October 6, 2026, at 10:00 AM ET.
• Season 7.1 also adds Change the Program and Fund the Campaign.
• Season 7.1 includes Invasion and Escalation changes, online stability improvements, Pause Menu loadout visibility, Rebirth loadout changes, balance adjustments, and numerous fixes.
• Official mod support has been removed, while several former mod-based quality-of-life options are now built into the game.

The Chemical Leak event basically asks you to survive The Outlast Trials with one more problem breathing down your neck: the environment itself is now trying to kill you.

Find the leak. Follow the hiss. Shut the valve. Get out.

And whatever you do, spend those Tokens before October 6.

Image Sources:

• Featured Image Credit: Red Barrels
• Image Credit 2: Red Barrels
• Image Credit 3: Red Barrels