Your bathing suit is made from very special fabrics, usually polyamide, spandex and lycra are used to add stretch and shape. But they’re not made to stand up to machine washing. The best way to wash swimwear is by hand, in lukewarm water, using natural hand soap.  Gently massage and squeeze out excess water (never wring) and wrap it in a clean towel and gently press. Lay the suit flat in the shade and let it dry naturally.