I will stay in Madrid for a couple of weeks in july. I was wondering if there are public swimmingpools where I can go when the weather is hot. Can anyone give me some addresses of outdoor swimmingpools?

Try this link. It should take you to a list of all the pools around town. Your best bet is probably the municipal pool at Lago, in the Casa de Campo. Cheap and cheerful. For a quieter day out, fewer children and so on, try the private pool called Stella, in Arturo Soria. It's more expensive. And if you really want to splash out, head for the spectacular roof-top pool in the Hotel Emperador on the Gran Via. It's really expensive.

http://www.guiademadrid.com/guia/n_deporte/base.asp?Tipo=piscinas