船舶水污染防治技术政策解读：灰水管控与法律缺失

In addition, in the 'Technical Policy for the Prevention and Control of Ship Water Pollution,' both blackwater and greywater are considered sewage, and it also requires the gradual implementation of greywater management. It states that in water areas where domestic sewage is not allowed to be discharged, such as drinking water source protection zones, measures should be taken to collect and store domestic sewage in corresponding on-board facilities and close drainage valves to prevent domestic sewage from entering the environment water bodies. The relevant control measures should be recorded according to regulations. However, this document is only a guiding document and lacks legal enforceability.