The code requires brokers to establish a trust account when they receive money on behalf of another person for their services, with some exceptions.
It requires brokers to act in good faith and to place the interests of the client before the interests of an intermediary or a related party.
The code also requires brokers to not disclose confidential information.
The code is being introduced in phases, with some requirements starting from July 1 and the others from October 1.
The ACCC said the phased approach gives intermediaries the time they need to be compliant.
The ACCC is responsible for enforcing the code and monitoring compliance and taking enforcement action when appropriate.
The code only applies to intermediaries in the Murray-Darling Basin.
The association representing water brokers already has a code applying to members, and president of the Australian Water Brokers Association, Andrew Martin, said the association had long been arguing for an industry code.
Mr Martin said the requirements should not be any surprise for brokers who were members and acting in the best interests of clients.
However, the code is legally enforceable and the final details were only concluded in June, so brokers have been scrambling to ensure their documents and compliance were up to date.
The association has secured legal advice of its own which has been distributed to members.
The new code will only apply to the Murray-Darling Basin, but most trading activity is likely to occur within the basin.
“But if you are working in Northern Territory or far north Queensland, and you are not a member of our association, you are not covered by a code,” Mr Martin said.
Water company, H2OX, notes that from October 1, all intermediaries must publish their fees on their website, which it says is a welcome change and a definite improvement for transparency in the market.