It doesn't matter how many lengths you can do - or how fast you can do them - if your posture, strokes and breathing are all out of kilter. Veronique Mistiaen on how to make the most of your trips to the pool.

Worries about small boys peeing in the swimming pool or your mascara running pale into insignificance when you consider that the water you are swimming through, and perhaps even swallowing, could contain bacteria, viruses and parasites.