Green Cleaning Guides

Does Washing Clothes in Cold Water Really Get Them Clean? We Dive into the Data

Written by Kay Baker, MS, OTR/L — CEO & Co-Founder • Reviewed by Matthew Keasey, Ph.D. — Chief Science Officer • Last reviewed: November 19, 2025

Transparency note: This article cites government sites, standards bodies, and peer-reviewed sources wherever possible. Educational only, not medical or legal advice.

There’s a bit of muscle memory to doing laundry, isn’t there? You toss in the clothes, add the soap, and instinctively turn the dial to "Warm" or "Hot." It's a habit passed down through generations, rooted in a simple belief: heat kills germs and blasts away dirt.

For a long time, that was true. But clinging to that old habit in a modern laundry room is one of the single most expensive and energy-wasteful things we do.

The skepticism is understandable. Can cold water really handle your weekly grime, sweaty gym clothes, and everyday messes?

The science, the data, and the real-world results all point to a resounding yes. It’s time to rethink the heat.

The Shocking Cost of Hot Water

Let’s start with the hard numbers. According to sustainability experts and ENERGY STAR, approximately 90% of the energy your washing machine consumes is used to heat the water. Only a tiny 10% is used to actually power the motor and tumble your clothes.

When you switch from a hot cycle to a warm one, you cut that energy use in half. When you switch to cold, you virtually eliminate it. Over the course of a year, this simple flick of the wrist can save you up to $60 or more on your utility bills and prevent hundreds of pounds of carbon emissions from entering the atmosphere.

That’s a huge win. But it only matters if the clothes actually get clean.

The Science: Why Cold Water Works Now

The reason hot water was once necessary is because old-school detergents were basic soaps that needed heat to effectively break down grease and grime. Modern detergents are a whole different ballgame.

The secret lies in cold-water enzymes.

As we explored in our guide on whether eco-friendly detergents actually work, high-quality modern detergents are formulated with specialized enzymes. These a re not just soaps; they are targeted proteins designed to attack specific stains at a molecular level, and crucially, they are engineered to be most effective at temperatures below 68°F (20°C).

• Using hot water can actually "cook" protein stains like blood or grass, setting them permanently.

• Using cold water allows these enzymes to do their job perfectly, breaking down the stains without damaging the fabric.

Your detergent is doing the heavy lifting, not the heat. The only thing hot water is guaranteed to do is run up your energy bill.

The Unseen Benefit: Saving Your Clothes

Beyond saving energy, washing with cold water is one of the best things you can do for the longevity of your clothes. Hot water is harsh. It causes:

• Fading: It breaks down dyes in fabrics, causing your vibrant colors to look dull and worn out.

• Shrinking: It can cause natural fibers like cotton and wool to constrict and shrink.

• Damage: It can damage delicate fabrics and elastics, reducing the lifespan of your favorite garments.

Cold water is gentler on fibers, keeping your clothes looking newer for longer. It’s like choosing a gentle hand-wash over a power-scrub.

The Exception to the Rule: When to Use Hot Water

Being a savvy, sustainable launderer means knowing when to break the rules. While cold water is the best choice for 9 5% of your laundry, there are two key times when hot water is still the right call:

1. Sanitizing After Illness: If someone in your household has been sick, a hot water wash (at least 140°F / 60°C) is effective at killing bacteria and viruses on bedding and towels.

2. Tackling Heavy Grease: For intensely greasy items, like a mechanic’s work clothes, the heat can help break down heavy-duty oils more effectively.

For everything else? The cold path is the clear winner.

Embrace the Cold

Making the switch to cold water is a powerful, simple change. It’s a core tenet of a truly sustainable laundry routine that saves you money, extends the life of your clothes, and dramatically reduces your carbon footprint, all without sacrificing a deep, genuine clean.

Ready to embrace the cold? Pair the smart habit with a smarter detergent designed to excel in it.

Shop Our Cold-Water Optimized Laundry Powder