He said the city’s drainage system - including water gates, pumping stations and water tunnels - had functioned efficiently.
The BMA had now cleaned out 97% of the city's drains and reduced water levels in canals in preparation for more rain.
Deputy city clerk Jumpol Sampaopon said Bangkok is situated on soft soil and on a low-lying plain. The land was subsiding at a rate of one centimetre to 10 centimetres each year.
The 100-130mm of rain this month caused a flood five to 20 centimetres deep in some low areas, partly because the influx of rainwater pushed up water levels in the canals and the floodwater on the roads could only drain off slowly.
The BMA will improve the water flow in canals which have only a low degree of slant that means the water runs out slowly, he said.
Meanwhile, Department of Corrections director-general Suchart Wong-anantchai said his department has 1,000 inmates ready to help dredge canals and clean drains in inner Bangkok to help combat any flooding.
Many main roads in the capital city were flooded on Tuesday after heavy rain, leaving many motorists stranded on roads for hours.
Pol Col Suchart Wong-anantchai, director-general of Department of Corrections, said the department would survey the spots which were flooded Tuesday to locate the problems.
If the problems were along the 3,500 kilometres of drains which had earlier been dredged, the department would send prison inmates to redo the job.
If the problems were found to be from drainage pipes being too small, the department would inform the Bangkok Metropolitan Administration and the government so they could take action to correct it.
The department had 1,000 inmates ready to help the BMA drain the water during heavy rain.
Pol Col Suchart said prisons nationwide been instructed to select well behaved inmates to perform public services, with a target of a total of 2,000 prisoners on stand by.