Bangkok Bank, the country's largest bank, announced that it arranges Bt45 billion for branches and ATMs nationwide.
The biggest cash reserve belongs to Krungthai Bank, at Bt57 billion.
Kasikornbank prepares Bt28.2 billion for the period, while Bank of Ayudhya sets aside Bt13.4 billion.
According to University of Thai Chamber of Commerce, spending during last year's water festival hit Bt103 billion, a new high in six years since 2007.
Kasikorn Research Centre's survey showed that Bangkokians will spend Bt31.5 billion during this year's festival.