Why 30°C Weather Could Cost You £30,000 in Lost Productivity

So far, 2025 has delivered exactly what climate scientists predicted, and then some. Spring 2025 became the UK's warmest and sunniest on record, with temperatures 1.4°C above the long-term average.

 June 2025 was England's warmest June since records began in 1884, and the UK's second warmest. Temperatures like this have consequences beyond hyped-up ice cream sales.

When temperatures rise above 25°C, your business faces more than sweaty employees. You face a real productivity crisis, tricky legal situations, and genuine health risks for your team. While you can't turn the sun down, you can make sure the workspace is adapted for hot conditions to help alleviate the worst symptoms of heat stress in your workforce.

When It Gets Hot, Work Gets Harder

The hidden cost of hot weather on UK businesses is shocking. Research shows that UK workers are up to 30% less productive when temperatures exceed 30°C (similar to losing one and a half workdays per employee each week during a heatwave). For a business with 100 employees, that's thousands of pounds down the drain during peak summer.

The Office for National Statistics has the numbers to prove it. They estimate an average annual loss of £1.2 billion between 1998 and 2021, with extreme years like 2020 hitting as high as £5.3 billion in lost productivity.

Recent research from the University of Exeter found that even in air-conditioned spaces, productivity drops by 0.83% for each degree above 25°C. 

When your team gets heat stress, their brains go into survival mode. Instead of focusing on that important report or solving customer problems, their minds are busy trying to cool down. 

Research also shows that 41% of UK workers admit to pulling a sickie when the weather's nice, jumping to 60% among 18-24 year olds. Internet usage actually drops on sunny days as people sneak away from their screens. 

While stopping this seems impossible, providing a more comfortable environment for conscientious employees coming to work heat or no heat is the least we can do, and that includes access to fresh, good-quality cool drinking water.

Providing Hydration As A Legal Requirement

Understanding what you need to do around workplace hydration can save you from headaches later and keeps your team safe.

Under the Health and Safety at Work Act 1974, you need to keep your workforce healthy and safe. The Workplace Regulations from 1992 spell out exactly what this means for drinking water.

You must provide "wholesome" drinking water to everyone who works for you. Water that's:

• Clean and safe to drink

• Available whenever people need it

• Easy to get to from anywhere in the workplace

• Kept separate from washing facilities

• Served with clean cups or glasses (or disposable ones)

Just placing a water cooler in the corner won't cut it. You need to make sure work patterns, location, or busy periods don't stop people from staying hydrated.

Your Legal Responsibilities Go Further

UK law sets minimum workplace temperatures (16°C for normal work, 13°C for physical work), but there's no maximum. The law just says temperatures should be "reasonable", which isn't helpful. This ambiguity has caught Unions’ attention. Unite proposes legal maximum temperatures of 27°C for strenuous work and 30°C generally, while the GMB Union advocates for a 25°C maximum. The NASUWT Teachers' Union suggests a 24°C limit for classrooms. The TUC similarly calls for work to stop above 30°C, or 27°C for those doing strenuous jobs.

Currently under the Employment Rights Act 1996, workers can refuse to work if they believe conditions present a "real risk of serious and imminent danger." The threshold is high, and employees are expected to raise concerns with employers first.

However, if unions feel appropriate, we could see times when certain conditions mean no workers turn up unless you air-condition the place below certain thresholds.

For now, your responsibilities include identifying who might be most at risk (pregnant women, people with health conditions, etc.), training everyone on heat stress signs and emergency procedures, ensuring people can check the temperature with accessible thermometers, and have access to quality hydration at all times. 

How to Spot Heat Stress

Understanding what heat stress does to your employees helps you spot problems early and act before things get serious. Heat stress follows a predictable path:

Early Warning Signs:

• Dehydration and muscle cramps

• Heat rash and feeling really thirsty (though by the time you're thirsty, you're already behind)

• Feeling faint and tired

• Dizzy spells, feeling sick, headaches

• Sweating loads as the body tries to cool down

When Things Get Serious:

• Heat stroke with hot, dry skin

• Getting confused, fits, potentially passing out

• Heart racing and working overtime

• Risk of heart attacks, kidney problems, and other serious complications

The 2022 UK heatwave showed just how dangerous this can get—2,985 extra deaths and over 5,000 premature deaths among people over 70.

Impact on Productivity

Heat makes you worse at your job. When people are physically uncomfortable, their brains split attention between the task at hand and trying to cool down. Heat directly affects focus and concentration on complex issues, decision-making and problem-solving, and coordination for everyday tasks.

Being hot makes people grumpy. Really hot people are more likely to snap at colleagues, misinterpret comments, and generally make the workplace less pleasant for everyone. Extended heat exposure can worsen depression, anxiety, and stress, and mess up sleep patterns so people show up already tired.

Practical Solutions That Work

Good workplace hydration varies by environment. A climate-controlled office has different needs from a factory floor or construction site.

Office Environments

Even with air conditioning, office workers face hydration challenges. People get focused on work and forget to drink, and all that coffee and tea can make dehydration worse.

• Where You Put Water Stations Matters: Keep them away from heat sources like printers and servers, and make sure there are several around the office. People drink more when water is visible and convenient—out of sight, out of mind.

• Make It Taste Good: People drink way more when water tastes nice. Modern filtration gets rid of that chlorine taste that puts people off, and having sparkling or flavored options can boost consumption.

Factories and Industrial Sites

Industrial environments are trickier because of heat-generating equipment, physical demands, and safety gear that makes cooling harder.

• It's Not Just About Water: When people are sweating buckets, plain water might not cut it. They need to replace the salts and minerals they're losing. Consider providing electrolyte drinks alongside regular water.

• Make It Easy to Access: Placing water stations in several strategic locations works well, and you might need longer breaks to give people proper time to cool down and rehydrate. Make hydration part of the workflow, not an extra hassle.

• Work with Safety Gear: Some hydration solutions work with PPE - hands-free dispensers like water fountains that don't interfere with protective equipment.

Hot Environments and Outdoor Work

When the work environment is inherently hot, hydration becomes a safety protocol.

• Structured Hydration Breaks: Mandatory breaks every 30-60 minutes during extreme heat, with supervisors trained to spot early heat stress signs. Little and often beats chugging loads of water in one go.

• Time It Right: Scheduling physical tasks before 11 AM or after 3 PM avoids the worst heat and dramatically cuts heat stress risk.

• Be Ready for Emergencies: First aid supplies, trained people, and clear procedures for heat-related problems. Catching heat exhaustion early can prevent it becoming life-threatening heat stroke.

Turning Legal Requirements into Business Benefits

Good hydration strategy can give you a competitive edge through better productivity, lower costs, and happier employees.

The numbers are compelling: for a £1 million business, preventing productivity losses over a typical summer heatwave period could save £30,000 or more.

Start with the basics: get cooling systems working, use fans strategically, block solar heat, and create proper rest areas. Identify heat sources and deal with them: insulate equipment, move workstations, time activities for cooler periods.

Make hydration part of your health and safety approach. Include it in workplace assessments and train everyone on heat stress symptoms, with extra training for supervisors.

Be efficient by using modern hydration solutions that come with maintenance, cleaning and easy ordering and monitoring.

What's Coming Next

After the record-breaking start to summer, businesses need to be ready for more of the same. The Met Office's latest work shows that heatwaves are becoming more frequent and intense. 

Developing future-ready policies means moving from reacting to emergencies to preventing problems. This includes detailed heat response plans, temperature control and hydration solutions, relationships with occupational health experts, and flexible working arrangements you can implement quickly when needed.

Advanced water filtration, smart monitoring, and serviced hydration systems will become more important. These technologies help you maintain good hydration even during extended heat waves that put strain on infrastructure and supply chains.

Ready to protect your workforce from the heat? Eden Springs provides complete hydration solutions designed for UK businesses facing rising temperatures. From bottled water coolers and mains-fed systems to touchless dispensers with BRITA filtration, we'll help you choose the best solution for your workplace. With flexible rental or purchase options, professional maintenance every six months, and our MyEden platform for easy ordering and delivery management, we handle everything so you can focus on running your business. 

Get a free consultation and quote today.