While people are on boats they will need to go to the toilet. The waste that is collected in a toilet is called sewage. Most smaller boats will have no way of treating sewage for it to become completely harmless if emptied into the environment. If boat sewage is emptied into rivers, lakes, estuaries or close to shore, the water can become polluted.
Each Australian State and Territory has its own regulations about what can happen with boat sewage. Check with your State or Territory EPA for the local laws. For the environment, it is best to dump this sewage into a disposal facility on shore. However, when there are not enough of these facilities it can be a problem for people with boats.
Sewage cannot be dumped in sensitive areas, such as inland waters and around special environments like coral reefs. In Queensland a boat must be more than five kilometres from shore before boat owners can empty their boats' sewage. If a boat does have a fixed toilet on board, the toilet must have a built in machine that mashes all solid material going into the toilet.
Even if there is a sewage treatment system onboard, the places where treated sewage can be discharged into the water will be different depending on the grade of treatment. At the highest level of treatment (Grade A), there are no restrictions. For Grade B, a boat must be at least 700 m from sensitive areas. For Grade C, a boat must be at least 1km from sensitive areas.