Does anyone know about some nice lake near Bangkok where i could go with my family during weekends?

Best regards.

Over & Out.

total entertainment aka te wake and ski.

http://tewake-ski.com/

little restaurant on the lake, plenty of room for the kids to play, operated by an american and if you want to ski or wakeboard excellent boats and coaches.

well worth the trip

About an hour's drive north of Bangkok, it seems:

https://maps.google.com/maps?saddr=Sathon+Nuea+Road+Bangkok+Thailand&daddr=tewake+ski+thailand&hl=en&ll=13.864747,100.546875&spn=0.729297,1.234589&sll=13.911407,100.515289&sspn=0.72915,1.234589&geocode=FZZf0QAd0_H9BSlPO3ZCzZjiMDHrTz_UKEBPHQ%3BFYNe1wAd7Ff9BSGPG69uvcvxoClDC9bjWXziMDGPG69uvcvxoA&oq=sathon+road,+bangkok&mra=ltm&t=m&z=10

this reservoir right in Bangkok behind Seacon Sq. on Srinakharin Road

has plenty of watersport from sailing to windsurfing, and it's run by Bangkok City hall, which is cheap compared to private business