How to wash leakproof underwear (and what quietly kills the absorbent layer)

Leakproof underwear works because of what is inside it: a thin absorbent core that pulls moisture off your skin, holds it, and a barrier layer that stops it reaching your clothes. Every one of those layers is fabric, and fabric only lasts as long as the way you wash it. Look after the core and a pair is built for 100+ washes at 30°C. Treat it like a towel and you will feel the difference within a few months.

Here is the whole routine. It takes no more effort than your normal washing.

Before the first wear: wash it once

New absorbent fabric leaves the factory with a light finishing agent on it. It is harmless, but it slows the top layer down — a brand-new pair can take three to five seconds to start pulling moisture in, which feels like it is not working. One wash removes most of the finish; absorbency reaches full strength after two or three washes. So wash before you wear, and do not judge a new pair on its first day.

The routine

1. Rinse after wearing

Rinse the gusset under the cold tap until the water runs clear, give it a gentle squeeze, and drop it in the laundry basket. It stops anything settling into the fibres between wears. It does not need to soak, and it does not need to be washed the same day.

2. Machine wash at 30°C

Cold or 30°C, gentle cycle, in with your normal laundry. Ordinary detergent is fine. Heat is the enemy of the barrier layer, so never a hot wash — it slowly stiffens and cracks the waterproof layer, and once that goes, the pair is finished. A mesh laundry bag is a nice-to-have, not a must.

3. Dry inside out, in the air

Turn each pair inside out so the core faces the air, then hang it or lay it flat. Overnight is enough — it is ready by morning. Direct sun for a short while is fine; leaving it to bake all day is not.

4. Store it like normal underwear

Once dry it goes in the drawer with everything else. It looks the same as the rest, which is rather the point.

The four things that kill the absorbent layer

• Fabric softener. Softener works by coating fibres in a thin waxy film. On a towel that makes it feel soft; on an absorbent core it makes it waterproof — the opposite of what you want. Skip it every single time. If a pair has already had softener, a few plain washes will strip most of it out again.
• The tumble dryer. The heat does the same damage as a hot wash, faster. Air dry, always.
• Bleach. It weakens the barrier layer and the elastic. If you want extra freshness, a cold-water rinse straight after wearing does more than any chemical.
• Ironing. There is no reason to, and the plate temperature can damage the barrier in one pass.

“It smells” — what to do

A pair that is rinsed after wearing and washed at 30°C should come out fresh. If one does not, the usual cause is softener build-up or a pair that was left damp in the basket for days. Run it through a normal wash with a cup of white vinegar in the rinse compartment, then a second plain wash. That resets it.

How long does a pair actually last?

Washed this way, a pair is built for 100+ washes. In a rotation of three pairs where you wear one every day, that is comfortably over a year. Rotating means each pair rests between wears, which is gentler on the elastic and the core than wearing the same one back to back — which is why we recommend three pairs as a minimum.

The Calm Wear Women's Leakproof Brief is a high-waist bamboo brief with a four-layer core, sizes S–XL, delivered free in a plain bag anywhere in South Africa. One pair is R599; three pairs are R1,199 (buy 2, get 1 free). The full care instructions are also on our care guide page.

Not sure about your size? Message us on WhatsApp with your waist measurement before you order and we'll confirm it.