Shower gel in the washing machine: the money-saving hack dividing opinion

Shower gel in the washing machine: one euro versus four

A bottle of shower gel costs less than a euro. A dedicated laundry detergent, four and change. The difference is so obscene that someone decided to test whether the former could do the latter's job. The result, according to their experience: clean clothes that squeak, with a splash of vinegar as the only addition. The same gel, they say, works for washing dishes and replacing branded dishwasher detergent. And the chemical explanation they offer is that both share the same foaming agent, sodium laureth sulfate, although shower gel doesn't contain surfactants that are harsh on fabrics.

The idea quickly found an audience. One person promised to mention it to their partner, who spends a fortune on branded detergent. Another recalled that storing the bottle upside down in the soap dish guarantees several extra washes. And a third contributed their own recipe: laundry powder made from grated Lagarto soap plus bicarbonate of soda, which comes out dirt cheap.

What doing the laundry really costs

The most repeated calculation is simple: the cheapest shower gel is around a euro, branded laundry gel tops four. Those who defend the hack claim a dessert spoonful per load is enough and that the consequences for the washing machine are nil, because after all it's soap. Vinegar, added to the dispenser tray, acts as fabric softener and neutralises the foam.

The rebuttal came quickly. A dessert spoonful is either enough for clean clothes or clothes that come out dirty, one sceptic summed up. In that case, don't add anything at all. Work clothes, they argued, aren't washed with that measly amount of gel, or soap. And the technical problem is real: shower gel produces loads of foam, so much it can overflow the washing machine. No wonder the first dedicated detergents boasted of controlled foam.

Some dismiss the whole idea outright as unnecessary. For three euros and change you can buy a multi-litre jug of own-brand laundry detergent, and for one euro, a regular dishwasher detergent. The comparison, they argue, is being made against posh brands, not against the reality of the shelf.

Vinegar: cheap fabric softener and its risks

Vinegar is the other star of the show. It replaces fabric softener, which is seen as a rip-off that doesn't make clothes much softer, whose smell fades quickly and which worsens dermatitis by lingering after the rinse. The chemical version: it's acidic, disinfects in a different pH range and improves detergent rinsing. In hard water areas, it softens.

But not just any vinegar will do. It has to be white vinegar, not the dark cooking kind. And there's a serious warning: not all washing machine seals can withstand its pH, which is highly acidic. It also shouldn't be mixed with soap in the same cycle, because soap works at a more neutral pH and the acid neutralises it. If you use it, better in a pre-wash or on its own.

Good old-fashioned soap wins again

The conversation drifted into older territory. Castile soap flakes, dissolved in hot water with bicarbonate of soda, work out at around fifteen cents per wash according to a detailed calculation doing the rounds. It doesn't foam, it's suitable for washing machines and it protects clothes. Lagarto soap, at 1.60 euros for a pack of three bars, is championed for the skin: some claim dermatologists shun it because it's too cheap to generate commissions.

The most radical option is making it at home. With used cooking oil and caustic soda at 2.85 euros a kilo, a litre of liquid soap costs about five cents and produces little foam. One kilo of caustic soda yields 75 litres. The premium version uses extra virgin olive oil and retains the glycerine, which is what cleans best and which the industry removes to sell separately.

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The question isn't whether shower gel washes. The question is how much of what we pay for a dedicated detergent is chemistry and how much is marketing. And that, at these prices, still has no reassuring answer.