Looking for a gym/health club

Hmmm not a good place to live if you're after facilities. Hard to think of anywhere near that is a health club with a pool too.
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If you're in the north of the gemeente, then Hofstade will be your nearest swimming pool.
http://www.bloso.be/centra/hofstade/Pages/Home.aspx
If you're in the south of the gemeente, Zaventem swimming pool will be the nearest.
http://www.zaventem.be/zwembad.html
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There is Castle Club in Wezembeek-Oppem
http://www.sports-valley.be/
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Or there is this spa, not sure if you can become a member, it has a year round outdoor pool. Very near to Steenokkerzeel village.
http://www.thermae-boetfort.be/EN/Home