The trend of DIY is everywhere, and homemade laundry "detergent"—often made from grated bar soap, borax, and washing soda—has captured the imagination of those seeking to save money and reduce chemicals. While the intention is admirable, the reality is that homemade laundry soap can be detrimental to your laundry, your washing machine, and your long-term budget.
Here is a deep dive into why this popular home hack falls short and why it's wise to stick with tested, commercially formulated laundry products.
1. It’s Soap, Not Detergent: A Crucial Chemistry Lesson
This is the most critical difference. What most DIY recipes produce is a soap, not a detergent.
Soap is traditionally made from natural fats and oils combined with an alkali (saponification).
Detergent is a synthetic, scientifically formulated cleaning agent.
Why does this matter? Detergents contain highly effective surfactants and specialized ingredients like enzymes and chelating agents. These components are essential for:
Lifting and suspending dirt in the water, ensuring it rinses completely away.
Working efficiently in modern washing machines (especially High-Efficiency/HE models) that use less water.
Preventing the redeposition of grime back onto your clothes.
Homemade soap lacks this precision and power, which leads to a host of problems.
2. The Soap Scum and Residue Problem
The biggest offender in the homemade soap saga is soap scum build-up.
Damage to Clothes
When soap interacts with the minerals in hard water (calcium and magnesium), it forms a waxy, sticky, insoluble residue—soap scum. This residue doesn't fully rinse away and clings to your fabrics. Over time, this build-up can cause:
Fading and Dullness: Whites turn grey or yellow, and colours look muted.
Stiffness and Roughness: Clothes feel rough, stiff, and scratchy, and towels lose their absorbency.
Unpleasant Odours: The soap scum traps body oils, dirt, and bacteria, leading to a persistent, musty, or "wet dog" smell, especially in athletic wear. This means your clothes are getting dirtier, not cleaner.
Damage to Your Washing Machine
That same sticky residue builds up inside your washing machine's mechanics, pipes, and drum, which is often unseen but causes significant long-term issues:
Clogs and Blockages: The build-up can clog hoses and drainage systems.
Mould and Mildew: The waxy film is a perfect environment for mould and mildew growth inside the machine, contributing to those bad smells.
Voiding Your Warranty: Appliance manufacturers design and test their machines using commercial detergents. Using homemade soap may void your warranty, leading to expensive repair bills.
3. Inconsistent and Subpar Cleaning Power
Commercial laundry detergents contain a complex blend of active ingredients to tackle different stain types and conditions. Homemade recipes simply cannot compete:
| Commercial Detergent | Homemade Soap |
| Enzymes break down specific stains (protein, starch, fat). | Lacks stain-fighting enzymes. |
| Chelating Agents manage hard water minerals for optimal performance. | Inconsistent performance in hard water, leading to scum. |
| Low-Suds Formulas work well in HE machines with minimal water. | Often creates too many suds, confusing HE machine sensors and hindering rinsing. |
| pH-Balanced formulas protect fabric dyes and integrity. | Ingredients like borax and washing soda are highly alkaline (high pH), which can be harsh on fabric fibers and cause colours to fade by stripping the dye. |
In the end, you may find yourself re-washing loads or needing to "strip" your laundry to remove residue, nullifying any perceived savings in time or money.
4. Risks to Fabric Integrity
The harsh, alkaline nature of common homemade soap ingredients (like washing soda and borax) can actively damage clothes over time.
Erosion of Fibres: The ingredients can gradually erode fabric fibers, causing garments to wear out faster, develop holes, or lose their elasticity (common in synthetics like spandex).
Damage to Delicates: Natural fibers like wool and silk are particularly vulnerable to high-pH cleaners, which can cause irreversible damage, such as shrinking or felting.
The Smarter Path to Eco-Friendly, Cost-Effective Laundry
If your motivation for using homemade laundry soap is sustainability or savings, there are much better, safer alternatives:
Look for High-Efficiency (HE) Certified Detergents: These are designed to perform optimally with less water and leave minimal residue.
Use Eco-Friendly Commercial Brands: Many reputable brands now offer biodegradable, plant-based, and non-toxic formulas that have been scientifically validated for effective cleaning. Look for transparent ingredient lists.
Use Less Detergent: Most people overestimate the amount of commercial detergent needed. Follow the directions carefully—using less is better for your wallet and the environment.
The cost of replacing ruined clothes and repairing a damaged washing machine far outweighs the small savings from a homemade batch. For effective cleaning, longevity of your garments, and the health of your appliance, the science is clear: skip the DIY laundry soap.