# Homemade Laundry Detergent: Useful Recipes, Limits & Real Risks

> Does homemade detergent actually clean? Castile soap & baking soda recipes, real chemical limits, and machine build-up risk explained.

**Published :** 2026-02-26 · **Updated :** 2026-03-25

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**Résumé :** **In short:** Homemade laundry detergent can work for everyday
maintenance, but it is not a miracle solution. On lightly soiled clothes, it
may suffice. On greasy stains, dull whites, and hard water, its limits are
real. The key issue is not "homemade vs store-bought" — it is chemistry: soap

- limescale = deposits. This guide gives you recipes that work, what they
  cannot do, and how to prevent machine build-up.

## At a Glance

- **Yes, it can work** for light soiling with careful dosing.
- **No, it is not universal**: greasy stains and bright whites remain difficult.
- **Build-up risk is real**, especially in medium-hard to hard water.
- **Three useful recipes**: liquid Castile soap, liquid black soap, and a powder version.
- **Pragmatic approach**: alternate with a machine-formulated detergent when needed.

## Soap ≠ Detergent: Chemistry First

The debate around homemade detergent is often moralised, when really it is a matter of physical chemistry.

Soap and synthetic detergent both clean, but not in the same way — and not with the same tolerance for hard water.

- **Soap**: a fatty acid salt produced by saponification (lye + oil/fat).
- **Synthetic detergent**: industrially designed surfactants, often more stable in the presence of calcium and magnesium.

The central problem with classic soap-based homemade detergent has been known for a long time:

**soap + hard water → insoluble calcium stearate (soap scum).**

Simplified equation:

**Ca²⁺ + 2 C₁₇H₃₅COO⁻ → Ca(C₁₇H₃₅COO)₂↓**

The precipitate does not "disappear" — it gradually deposits.

Observable consequences over repeated cycles:

- greying of fabrics,
- fibres becoming stiffer,
- lingering odours,
- residue on the drum, seals, and hoses.

> The soap-limescale reaction is a chemistry textbook classic. User reports and
> comparative tests confirm the same reality: in hard water, a soap-based
> detergent demands more vigilance than a modern detergent formula designed for
> that environment.

For a formulated option when you would rather not improvise, see also our guide on how to choose the right detergent.

## Real Castile Soap: How to Identify It

The term "[Castile soap](https://amzn.to/48721mK)" is used broadly, sometimes misleadingly.

The "72% oil" marker is itself often misunderstood.

### What "72%" Really Means

"72%" refers to the total proportion of saponified fats in the finished soap.

It does not mean "72% olive oil."

### Useful Label Checks

- **Short ingredient list** — Look for mentions like sodium olivate (olive) or sodium palmate (palm), with sodium hydroxide for saponification.
- **Few additives** — A genuine traditional Castile soap avoids synthetic fragrances, colourants, and long lists of auxiliary agents.
- **Historic manufacturers** — The most commonly cited UPSM members: Marius Fabre, Savonnerie du Midi (La Corvette), Le Sérail, Fer à Cheval.

Many products labelled "Castile soap" are actually syndets (synthetic detergents) or blends.

That is not necessarily "bad" per se, but it is not the same raw material — nor the same behaviour in the wash.

> UFC-Que Choisir published a useful investigation into the naming and actual
> compositions:
> 
> Savons de Marseille: c'est du propre? (March 2021)
> 
> .

**Genuine Castile Soap: Checklist Before Buying**

Before purchasing, check the INCI list, the fatty-acid content (72%), the absence of unnecessary additives, and the manufacturer's origin.

## Recipe #1: Liquid Castile Soap

This is the most widespread homemade detergent recipe. It can suit everyday laundry that is lightly to moderately soiled.

### Exact Amounts

- **40 g** of grated Castile soap
- **1 L** of hot water
- **1 tbsp** of [washing soda](https://amzn.to/4rUGAN0) (level)

### Step-by-Step

1. Finely grate 40 g of soap.
2. Heat 1 litre of water (do not boil).
3. Add the grated soap, stirring until dissolved.
4. Mix in 1 level tablespoon of washing soda.
5. Stir for another 2 to 3 minutes.
6. Let the mixture cool slightly, then pour into a clean container.

### Machine Dosing

Start with around 80 to 120 ml per cycle, then adjust based on the actual result (smell, feel, cleanliness).

Do not overdose "just to be safe" — overdosing increases residue and makes rinsing harder.

### Storage

Store for 1 to 2 months maximum.

The texture thickens at rest — that is normal. Shake before use.

To understand why some stains persist despite this recipe, see our tough stain solutions guide.

## Recipe #2: Liquid Black Soap

A simpler version to dissolve, useful for those who want quick preparation.

### Exact Amounts

- **2 tbsp** of soft black soap
- **1 L** of hot water
- **1 tbsp** of baking soda

### Method

Mix the black soap into the hot water, then add the baking soda.

Stir until homogeneous, let it cool, and bottle.

### What Works Well

- Everyday maintenance of lightly soiled clothes.
- Quick preparation with no grating step.
- Generally more stable texture than some grated soap recipes.

### Limits to Know

- Reduced performance on embedded grease stains,
- variable effectiveness on dull whites,
- results depend on water hardness.

## Recipe #3: Powder Version (No Water)

This version avoids the storage issues of liquid recipes and simplifies keeping.

### Exact Formula

- **200 g** of washing soda
- **100 g** of [sodium percarbonate](https://amzn.to/4lR6akp)
- **100 g** of baking soda

Mix dry in an airtight, dry jar.

### Dosing

Use **1 to 2 tbsp** per machine load depending on the load size and soil level.

### Advantages

- 🫙 **Good stability** — No water = long shelf life as long as the container stays dry.
- ⚖️ **Easy dosing** — Simple spoon measurement — no shaking a thickened liquid.
- 🧺 **Versatile on cotton** — Can suit sturdy household linen and non-delicate white cotton.

### Fabric Warning

This formula is alkaline. It is **not recommended for wool, silk, or delicate fabrics**.

If your goal is whiter whites, percarbonate can help — especially from 40 °C upwards. Details here: how to whiten yellowed laundry.

## Honest Comparison: Homemade vs Store-Bought

The useful point is not to declare a universal winner, but to know when each option is appropriate.

| Criterion            | Homemade                            | Store-bought                      |
| -------------------- | ----------------------------------- | --------------------------------- |
| Light stain removal  | ✅                                   | ✅                                 |
| Grease stain removal | ❌                                   | ✅                                 |
| Bright whites        | ❌                                   | ✅                                 |
| Cost per wash        | ✅ (usually lower)                   | ❌ (usually higher)                |
| Environmental impact | ⚠️ depends on ingredients and usage | ⚠️ depends on formula and dosing  |
| Build-up risk        | ⚠️ real risk with soap + hard water | ✅ formulated to minimise deposits |

Key references:

- **UFC-Que Choisir (March 2023, stain remover test)**: baking soda was among the least effective options on grease stains — sometimes "even worse" than commercial stain removers depending on the scenario.
- **UFC-Que Choisir (March 2021)**: warning about the "Castile soap" label and the actual composition of products.

For a broader environmental comparison (machines, energy, dosing, cycles), see also eco-friendly laundromat technologies.

## Build-Up: The Real Risk

This is the most underestimated topic in "magic recipe" content.

Calcium stearate does not just float in the water — it ends up depositing.

Affected areas:

- tub and drum,
- seals,
- hoses,
- detergent tray.

In many regions, water hardness can easily reach **15-20 gpg** (grains per gallon), qualifying as moderately hard to hard water.

That is enough to significantly increase the risk of deposits with soap-based detergents if machine maintenance is neglected.

> If you use a soap-based homemade detergent, run at least one empty hot cycle
> monthly at 90 °C (194 °F), with a visual check of the seal and detergent tray.
> You can supplement with a white vinegar cycle as needed depending on the
> machine's condition.

Step-by-step guide: how to clean your washing machine.

## Washing Soda, Baking Soda, Percarbonate: The Differences

> This page covers the **homemade detergent** logic. If your
> question is mainly about the product itself, see also
> 
> our complete guide to sodium percarbonate for laundry
> 
> . For white vinegar in the rinse, see
> 
> white vinegar and laundry: useful applications, limits, and mistakes to
> avoid
> 
> .

These three powders are often confused. They do not have the same pH nor the same use.

| Product             | Approx. pH               | Main Use                                    | Precautions                                        |
| ------------------- | ------------------------ | ------------------------------------------- | -------------------------------------------------- |
| Baking soda         | 8.5                      | Deodorise, lightly buffer alkalinity        | Limited cleaning action on grease stains           |
| Washing soda        | 11.4                     | Degrease and boost the detergent            | Avoid on wool, silk, and delicate fabrics          |
| Sodium percarbonate | Alkaline + active oxygen | Whiten/oxygenate, active from 40 °C upwards | Test on colour-sensitive items, protect eyes/hands |

- 🧴 **Baking soda** — More of a deodoriser than a powerful cleaner. Good complement, poor full replacement.
- 🧪 **Washing soda** — Strong on grease, but more aggressive. Respect dosages and compatible fabrics.
- ✨ **Percarbonate** — Oxygen-based whitening agent. Its activity increases with temperature.

To choose the right temperature based on fabric type and the chemistry you are using, see our washing temperature guide.

## Skin Impact: Think About Residue Too

Another angle often overlooked in homemade recipes is skin tolerance.

A "natural" formula is not automatically "neutral" for all skin types.

The real lever remains: correct dosing + sufficient rinsing + suitable fabric.

If you have reactive skin, see our full guide: detergent residue and sensitive skin.

## What About the Laundromat?



## Why Online Recipes Often Fail

Forums and social media are full of enthusiastic testimonials about homemade detergent — but also disappointed feedback a few months later. The gap comes down to two factors most recipes never mention.

### Hard Water Neutralises the Soap

Water hardness varies considerably from one area to another. A recipe that works in a soft-water region (approx. 5 gpg) can fail completely in a moderately hard area (approx. 15 gpg) or a hard-water zone (approx. 20+ gpg). In hard water, soap reacts with calcium to form calcium stearate — an insoluble deposit that cleans nothing and accumulates in fibres and in the machine. The recipe author may live in a soft-water area without realising it. Check your water hardness on your utility company's website or with a TH test strip (available at pet shops or online, approx. $5) before committing.

### Build-Up Is Gradual and Invisible

The second problem is that homemade detergent can seem to work fine for 2-3 months before the first signs appear. Soap deposits accumulate cycle after cycle in the drum, seals, and hoses. Symptoms arrive gradually: greying fabrics, a musty smell in the machine, less absorbent towels. At that point, the build-up requires deep cleaning (hot cycle at 90 °C + white vinegar, or even disassembling the detergent tray). Many users blame these symptoms on the machine or the fabrics — not the detergent.

**The right approach**: if you make your own detergent, schedule a monthly maintenance cycle at 90 °C (194 °F) with a machine-formulated detergent, and watch for three warning signs — drum odour, greying whites, and "cardboard-stiff" towels.

## When to Alternate with Store-Bought Detergent

The most pragmatic approach is not to pick a side (homemade or commercial), but to alternate based on need. Homemade detergent works well for lightly soiled everyday laundry: t-shirts, sheets, indoor clothes. For whites that need refreshing, stubborn stains (grease, blood, wine), or sportswear with a heavy bacterial load, a detergent formulated with enzymes and bleaching agents will deliver better results.

A workable rhythm: homemade for 3 out of 4 cycles, store-bought for 1 out of 4 (for whites or heavier loads). This regular cycle with a machine-formulated detergent also helps limit the gradual build-up described above.

Also consider testing your water every 6 months with a TH test strip (available at pet shops or online). If your water gets harder — which can happen after a source change by your utility — adjust your recipe or increase the alternation frequency.

## Common Mistakes

> **Warning:**
> - **Equating natural with universal**: a homemade recipe can be useful without being suited to every fabric.
> - **Using fake Castile soap**: the label alone does not guarantee a traditional composition.
> - **Overdosing to "wash better"**: this increases deposits, makes rinsing harder, and causes machine odours.
> - **Ignoring water hardness**: in medium-hard to hard water, the risk of soap scum increases.
> - **Using alkaline powder on wool/silk**: risk of fibre damage.
> - **Never running machine maintenance**: without a periodic hot cycle, deposits accumulate.

## Sources

- UFC-Que Choisir, "Savons de Marseille: c'est du propre?", March 2021: quechoisir.org
- UFC-Que Choisir, stain remover test, March 2023 (performance comparison, including baking soda)
- Standard soap chemistry principles: precipitation of calcium fatty acid salts in hard water

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