Are there any rules regarding waste water disposal- not sewage?

A new block of rooms has just been completed near us, and all the waste water outlets discharge directly into an open drain that passes by our house.

Fine when it rains a lot, but in the dry season there is virtually no water flow, so the stench of 20 rooms waste will be powerful as it stagnates beside us.

Thanks for replies by those that know.

That's a good question OP, and I would be interested to the answers.

When the contractor build my house, he build a tunnel through my front garden so all the grey water goes into the soi.

I dug a little channel to divert the water from going directly on to the street, as we haven't got main drains, but instead drain in a near by field.

When I queried his actions I was told this is perfectly legal in Thailand.

Still not happy with the situation but I have to live with it.