Thailand has monsoon rains 6 months of the year. It is a big part of life living in a tropical climate like Thailand.
It rains hard and water can build up 2+ feet deep in the streets in an hour.
Thai people are use to this happening and have learned to live with it.
You should too, if you plan to live in Thailand.
As with any flooding, cautions should always be taken when driving or walking through deep water.
The flood waters are very polluted and best to be avoided.
If you hate the rain, Thailand is not the place for you!