How to Wash a Mattress Protector Without Ruining It

When a waterproof protector stops being waterproof, people usually assume it wore out. It rarely did. In most cases it was cooked.

The barrier inside a modern protector is a thin polyurethane film bonded to the fabric. Fabric tolerates heat. Film does not. Get the temperature right and the protector will outlast several sets of sheets.

How often

Every two months is enough for most beds. Move to monthly if someone in the house has allergies, if a pet sleeps on the bed, or in hot weather when you're sweating more at night. Wash it immediately after a spill — the protector did its job, but liquid left sitting on it will still stain and smell.

Washing

• Cold or warm water, on a normal or gentle cycle. Nothing above 40 °C / 105 °F.
• Mild detergent, and less than you think. Excess detergent leaves a residue on the membrane that stiffens it over time.
• Wash it on its own or with sheets. Never with towels — lint works into the fabric — and never with anything that has a zipper or hook that could nick the film.

Three things that will destroy it

• Bleach. It breaks down the film directly. Chlorine bleach is the fastest way to turn a waterproof protector into a regular sheet.
• Fabric softener. It coats fibres to make them feel soft, and that coating clogs the pores the membrane breathes through. You end up with a protector that traps heat.
• High heat. Hot washes, hot dryers and irons all soften and crack the film. This is the one that catches most people.

If you remember one rule: keep it off high heat, and keep softener away from it.

Drying

Tumble dry on low or air-dry. Low heat is genuinely fine and it's what most manufacturers specify — it's sustained high heat that does the damage. Line drying works too, though direct sun for hours will age the film, so a shaded line is better.

Take it out while it's still very slightly damp and put it straight on the bed. It finishes drying in place and you skip the wrinkles. Don't iron it, and don't dry clean it.

Between washes

Air the bed for fifteen minutes before making it in the morning. Pulling the covers straight up traps overnight moisture against the protector, which is what eventually causes odour. Ideally, keep a second protector in the cupboard so the bed is never unprotected on laundry day — the night a mattress is bare is invariably the night something gets spilled on it.