The SRT is looking to private firms to build more toilets at the market in exchange for free ads at the toilets, Paisal Suprungrote, the acting chief of the market, said on Wednesday.
The most popular market for Thais and tourists has eight toilet locations, most of them old, and that is not enough to cope with users, especially on weekends.
Officials have surveyed new locations for toilets to be built and the construction will begin soon, the SRT official said.
The railway office, which controls the market, has an extra 70 million baht in this fiscal year's budget to improve other Chatuchak facilities, including roads and the electricity and drainage systems, he added.
About 8,480 vendors rent booths at the market from the SRT and their contracts are due to expire at the end of this month.
More than 2,000 vendors have renewed their leases for another five years for 3,154 baht a month.
Mr Paisal suggested the rest do it by the deadline falling next Tuesday. ''When the contracts expire on March 4, the SRT will not extend them,'' he warned.