You do not need to be able to swim to benefit from aquatic therapy. Your head does not go under the water. People with poor water confidence can also benefit as the pool varies in depth and you will only work in an area where you are comfortable.
For some treatments it may be beneficial to lie on your back and floatation devices can be used to support you in a relaxed, comfortable position. The therapists will check how confident you feel in the water and can tailor your treatment programme around you.