Homemade washing-up liquid: three-ingredient mix with black soap, bicarbonate of soda and soda crystals

Supermarket shelves are lined with brightly coloured bottles of washing-up liquid: Ultra, Power, Sensitive, Citrus. What hardly anyone pays attention to is the reality inside: a blend of chemical surfactants, fragrances and dyes that can pollute waterways, comes packaged in plastic, and often irritates the skin. For that reason, more and more people are switching to a straightforward homemade mixture - and suddenly stop buying washing-up liquid altogether.

Why conventional washing-up liquid can become a problem

Commercial washing-up liquids are designed to do two things well: cut through grease aggressively and smell “fresh”. To achieve that, several groups of ingredients typically end up in the bottle.

• Synthetic surfactants dissolve grease fast, but they do not always break down completely in the environment.
• Fragrances and colourants create a “freshness” impression, yet they are often unnecessary and can increase the risk of allergic reactions.
• Preservatives extend shelf life, but they add to the load on waterways and wastewater treatment.
• Plastic packaging is only partly recyclable; a large share ends up in general waste or is incinerated.

There is also the way many people use it: out of habit, large quantities go into the bowl. A high head of foam looks reassuring, but it says little about how well something cleans. The result is extra chemicals down the drain - and more contact with your skin.

"Choosing a homemade washing-up liquid saves plastic and money, while also reducing the amount of chemicals used in your own kitchen."

The simple mix: three ingredients instead of a chemical cocktail

This household alternative relies on three basic ingredients that you can buy in any chemist and that have been used at home for decades:

• Black soap (liquid)
• Sodium bicarbonate (bicarbonate of soda)
• Soda crystals

Liquid black soap provides the base and most of the cleaning power. Traditionally it is made from plant oils such as olive or linseed oil and does not rely on problematic additives. It removes grease without drying out the skin as harshly as many industrial products.

Bicarbonate of soda has a gentle abrasive effect and helps neutralise odours. Dried-on food comes away more easily without scratching non-stick pans or glassware. Soda crystals tackle grease more directly: they help turn fats into soap - meaning they become water-soluble - a classic technique borrowed from soap making.

How to mix your own washing-up liquid

To make around half a litre of homemade washing-up liquid, you only need small amounts of the three components. The version described here is easy to recreate:

1. Put 1 tablespoon of bicarbonate of soda into an empty, clean bottle.
2. Add 1 tablespoon of soda crystals.
3. Pour in liquid black soap to a depth of about 2 cm as the base.
4. Top up with hot tap water, leaving a little space at the top for shaking.
5. Close the bottle tightly and shake hard until the crystals have dissolved.

You end up with a mild yet very effective cleaner. If you like, you can add a few drops of essential oil - for example lemon or lavender. This is optional, but it can help remove unpleasant smells from plastic food containers or pans.

Version with grated household soap

In a more elaborate variation, you also add a traditional bar of plain household soap with no added extras. This produces a thicker, more strongly foaming washing-up liquid:

• 800 ml hot water
• 1 tablespoon black soap
• 1 tablespoon soda crystals
• 1 tablespoon bicarbonate of soda
• about 50 g finely grated household soap

Put all the dry ingredients into a bowl along with the black soap, pour over the hot water, and stir thoroughly until the soap has largely dissolved. Leave the mixture overnight, then dilute with a little cold water the next day if needed and decant into a bottle. The result is a viscous, foaming cleaner that can be used in much the same way as standard washing-up liquid.

How well does the homemade mix really clean?

At first, many people worry that a homemade cleaner cannot compete with the aggressive products sold in supermarkets. After several months of use, the experience tends to show the opposite: plates, cutlery and glasses come out clean and grease-free, and pots shine without leaving a smeary film.

One point stands out: this mixture produces noticeably less foam than familiar branded liquids. That can feel strange initially, but it does not reflect poorer performance. Foam is mainly created by particular surfactants and air - not by “extra cleanliness”.

"What matters is whether grease and food residue disappear - not how high the foam sits in the bowl."

A further benefit many households notice is that pipes seem to block more slowly. Soda helps dissolve grease inside the plumbing, reducing build-up. If you already rinse through with hot water regularly, you can take ongoing pressure off your kitchen drain.

Financial benefits: washing up for a few pence per litre

The ingredients for this homemade washing-up liquid are among the cheapest items on the chemist’s shelf. A packet of bicarbonate of soda, a pack of soda crystals and a bottle of black soap will make many litres of cleaner. When you work it out per bottle, the cost comes to only a few pence.

By comparison, branded washing-up liquids can cost several pounds per litre. On top of that come special offers, scented variants and “premium” versions that largely reflect marketing mark-ups. Mixing your own avoids that price spiral.

Less plastic, fewer chemicals, fewer irritations

Another change people often notice only over time is how their hands feel. Red patches, tightness or itching can ease when harsh chemicals are removed from daily washing up. Gloves are still sensible for long sessions at the sink, but many people find the homemade mix far gentler.

At the same time, plastic use drops. Instead of buying a new bottle every few weeks, you can refill a sturdy dispenser or an old bottle again and again. Buying larger packs of the base ingredients can also reduce packaging further.

Where homemade washing-up liquid reaches its limits

The mix is not perfect in every situation. For heavily baked-on dishes or burnt pans, an extra step often helps: soak overnight, optionally sprinkle a little baking powder or salt, and pour over hot water. Afterwards, the grime usually lifts far more easily.

For very delicate materials - such as natural-stone worktops or certain wooden surfaces - it is worth checking the manufacturer’s care instructions. Soda is alkaline and, in high concentrations, can attack some finishes. In the normal dilution used in washing-up water this is not an everyday issue, but concentrated solutions should not be left to dry on sensitive surfaces.

Practical tips for everyday use of homemade washing-up liquid

• Give the bottle a quick shake before each use so the ingredients redistribute evenly.
• If you have very hard water, add a splash of vinegar to the washing-up bowl now and then to prevent limescale marks.
• For glasses, a small squirt is often enough - less really is more.
• Wipe very greasy pans with kitchen paper first, then wash up. This saves cleaner and is kinder to your pipes.
• Once a month, flush the drain with hot water and 1 teaspoon of soda to help keep the pipe clear.

What the key ingredients actually do

Bicarbonate of soda is a household all-rounder: it neutralises odours, reacts mildly alkaline, and is also used for cleaning ovens, fridges or trainers. In this washing-up mixture, it helps loosen food residue and removes unpleasant smells.

Soda crystals are not the same as bicarbonate of soda: they are more strongly alkaline and much more powerful at dissolving grease. For that reason, they should be kept away from children and should not be inhaled. Used at the right dose in washing-up water, however, they are extremely effective against greasy films.

Black soap brings plant-based cleaning substances to the mix. Unlike many brightly coloured branded products, it generally avoids optical brighteners and problematic fragrances. Many versions are more readily biodegradable and are gentler on skin.

Once you understand what these three building blocks do, it becomes clear why many households stop repurchasing conventional washing-up liquid. The homemade mixture cleans reliably, costs very little, is kinder to the environment - and can be mixed again in minutes when the bottle is empty.