A mattress protector only works if you wash it. That sounds obvious, but a surprising number of people buy a protector, put it on the bed, and then wash it either far too rarely, or not at all until something goes obviously wrong.
The answer to how often you should wash a mattress protector is not complicated, but it does depend on a few factors: your household, what type of protector you have, and whether any specific events warrant an immediate wash. This guide covers all of it, plus exactly how to wash a mattress protector without damaging the waterproof membrane.
The Short Answer
For most households: every one to two months under normal use.
For households with young children, pets, or heavy sweaters: every two to four weeks.
After any spill, accident, or illness: immediately.
If your protector has been on the bed for longer than two months without washing, wash it now regardless of whether anything visible has happened. Sweat, skin oils, and dust mites accumulate invisibly, the protector looks clean long after it has stopped functioning as a genuine hygienic barrier.
Why Washing Frequency Matters
A mattress protector sits between your fitted sheet and your mattress. It is the last line of defence before moisture, sweat, and debris reach the mattress itself which cannot be washed. The average person perspires roughly a cup of fluid per night during sleep. That moisture passes through your sheets and into the protector. Over weeks, oils and salts from sweat build up in the fabric, reducing breathability, softening the waterproof membrane, and creating conditions that support dust mites and bacterial growth.
Regular washing removes this buildup and restores the protector’s function. A protector that is not washed regularly is not really protecting anything, it is just an extra fabric layer with diminishing hygiene value.
How Often to Wash: By Household Type
Standard household (adults, no pets, no young children)
Every one to two months. Your sheets are being washed weekly, which significantly reduces how much passes through to the protector, so monthly or bimonthly washing is sufficient.
Households with young children
Every two to four weeks, or immediately after any accident. Young children sweat more relative to body weight than adults, and bedwetting (even occasional) means the protector is doing real work. If your child has a wet night, wash the protector the same day. Do not let it sit damp, that is, moisture trapped between a waterproof layer and a mattress promotes mildew even if the protector technically contained the liquid.
Households with pets on the bed
Every two to four weeks. Pet dander, oils, and hair accumulate quickly. If your pet has an accident on the bed, wash the protector immediately.
Hot sleepers and heavy sweaters
Every two to four weeks. If you regularly wake up damp, your protector is absorbing significantly more moisture than average. More frequent washing prevents sweat residue from degrading the fabric face and membrane over time.
During or after illness
Wash immediately after recovery. Illness means bacteria and viral particles in respiratory droplets can reach your bedding. Wash the protector and your sheets at the end of an illness on a warm cycle.
How to Wash a Waterproof Mattress Protector
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Use warm water, not hot. The most common way to damage a waterproof mattress protector is washing it in hot water. Heat degrades the TPU membrane (the layer that actually provides waterproofing) causing it to delaminate from the fabric face over time. Warm (30–40°C) is sufficient to clean effectively.
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Use a mild, fragrance-free detergent. Harsh detergents, enzyme cleaners, and bleach all degrade both the cotton face fabric and the waterproof membrane.
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Skip fabric softener entirely. Fabric softener deposits a waxy coating on the fabric fibres that reduces breathability and compromises the surface water repellency over time.
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Gentle or normal cycle. Avoid heavy-duty or bulky cycles with high agitation.
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Wash alone or with bedding only. Do not wash with towels or items with zips and velcro that can snag and damage the membrane.
How to Dry a Waterproof Mattress Protector
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Tumble dry on low heat. High heat is the single fastest way to damage a waterproof membrane, it causes the TPU layer to delaminate, blister, or crack. Low heat or air-only is correct.
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Remove promptly. Do not let the protector sit in the dryer after it finishes.
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Air drying is fine and gentle. Hang it flat or over a wide surface rather than folded over a line, which can crease the membrane.
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Make sure it is completely dry before returning to the mattress. A damp protector placed on a mattress traps moisture, which can cause mildew. If in doubt, give it extra drying time.
How to Wash an Organic Cotton Mattress Cover (Non-Waterproof)
If your protector is a plain woven organic cotton cover without a waterproof membrane:
- Machine wash warm, gentle cycle.
- Mild, fragrance-free detergent.
- No fabric softener.
- Tumble dry low, or line dry.
- Wash every three to four weeks for most households, more frequently than a waterproof protector, since there is no membrane to contain moisture.
How to Know If Your Mattress Protector Needs Replacing
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The waterproof membrane no longer beads water. Pour a small amount of water on the surface. On a functional waterproof protector, water beads and rolls off. If it soaks in, the membrane has degraded.
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The membrane is visibly delaminating. Look for areas where the backing is separating from the face fabric, or where the surface has a crinkled, puckered, or uneven texture.
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Persistent odour that does not wash out. If the protector retains odour after washing, it is time to replace.
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Elastic skirt no longer holds the corners. A protector that pops off the mattress corners overnight is not protecting the mattress.
Quality organic cotton mattress covers last 5 or more years with regular washing. Waterproof protectors with TPU membranes typically last 3–5 years.
Stain Treatment
Treat stains before washing, not after. A stain that has been through a dryer cycle on heat is likely permanent.
For urine stains: cold water and detergent immediately. White vinegar diluted 1:1 with water is effective on urine odor. Apply, let sit for 15 minutes, then rinse and wash.
For blood stains: cold water only, never warm or hot. Hydrogen peroxide on white or light-coloured protectors works well; avoid it on coloured fabrics.
For sweat residue and yellowing: a paste of baking soda and water left on the area for 30 minutes before washing effectively lifts sweat residue without damaging the fibre.
How to Store a Mattress Protector Between Uses
- Make sure the protector is completely dry before storage.
- Store folded loosely in a breathable cotton bag or pillowcase, not in a sealed plastic bag.
- Avoid storing in direct sunlight for extended periods.
Frequently Asked Questions
Can you wash a mattress protector in a regular washing machine?
Yes — most mattress protectors are designed to be machine washed at home. Use warm water, a gentle or normal cycle, mild detergent, and no fabric softener. For king-size protectors, make sure your machine has enough capacity for the load to move freely.
Can you put a mattress protector in the dryer?
Yes, on a low heat or air-only setting. High heat is the most common cause of waterproof membrane damage. If your dryer does not have a reliable low-heat setting, air drying is the safer option.
How do you wash a mattress protector that has been peed on?
Remove it immediately and rinse under cold water to dilute the urine. Then wash the full protector on a warm gentle cycle with mild detergent and optionally a splash of white vinegar in the rinse cycle to neutralise odour. Dry thoroughly on low heat before returning to the bed.
Can you dry clean a mattress protector?
Not recommended. Dry cleaning solvents are harsh on TPU membranes and organic cotton alike. Machine washing at the correct temperature is the right method.
How often should you replace a mattress protector?
Every 3–5 years for a waterproof protector. Every 5+ years for a plain organic cotton cover with regular washing and no physical damage.
Does washing a mattress protector ruin the waterproofing?
Only if you use hot water, bleach, or high dryer heat. Washing on warm with mild detergent and drying on low preserves the waterproofing for the full life of the product.
Shop Whisper Organics GOTS-certified organic cotton mattress covers — breathable, PFAS-free, and machine washable.
