12.1 Blackwater system

The blackwater system collects sewage from the toilet and transfers it to a separate holding tank. Depending on the boat’s configuration, the toilet flushes using either sea water or fresh water.

  • Drain the blackwater tank when leaving port by using the port’s drainage equipment. The drain fitting on the deck is indicated with the text BLACK WATER.
  • You can also drain the tank into the sea by using the sea drainage valve. Keep the valve closed under normal conditions. The valve can be sealed.
  • It is recommended to keep the toilet's seawater flushing intake valve closed when the toilet is not in use.
Figure 1. Blackwater system components

1

Freshwater tank

5

Blackwater tank

2

Toilet flushing water line*

6

Blackwater tank sea drainage valve

3

Toilet

7

Blackwater tank vacuum drain fitting

4

Toilet flushing water intake valve**

8

Blackwater tank breather through fitting

* Available only when the boat is equipped with a fresh water flushing toilet.

** Available only when the boat is equipped with a sea water flushing toilet.

Parent topic: Toilet and septic tanks