Waste water capacity is a hull volume decision that must be made before the interior is designed. Holding tank volume follows guest count multiplied by trip length, and it competes with fuel, fresh water and accommodation for the same space. Vessels built with a token tank end up with an operational problem they cannot solve except by doing something they should not do inside a conservation area.
Why this matters more here
Komodo National Park is a managed conservation area and the anchorages are enclosed, shallow and biologically sensitive. Discharge of untreated sewage into these waters is not acceptable, and enforcement attention on vessel waste has increased as visitor numbers have grown. Beyond the regulatory position there is a commercial one: guests are paying to visit a marine conservation area, and operators whose waste practice is visibly poor are increasingly called out for it.
Sizing the holding capacity
The calculation is guests plus crew, multiplied by daily production per person, multiplied by the days between opportunities to discharge legally or pump ashore. The trap is that production per person on a liveaboard is high — showers after every dive, and the water you produce with the watermaker becomes waste water within hours. Generous fresh water production without matching waste capacity simply moves the problem downstream.
Separate grey and black tankage is worth considering. Grey water — showers, basins, galley — is produced in far greater volume than black water, and mixing them means a single tank fills fast. Segregating allows different handling strategies for each, and grey water is the flow most often forgotten entirely at design stage.
Treatment options
Holding only is the simplest arrangement: everything goes in a tank and is discharged where permitted or pumped ashore. It needs the most volume and depends on shore facilities or legal discharge opportunities being available.
Treatment systems process sewage aboard to a treated standard. They reduce, but do not eliminate, the need for holding capacity, and they add a machine that needs power, consumables, service and crew competence. On a vessel operating in a conservation area, a properly maintained treatment system plus adequate holding is the arrangement that gives you the most operational freedom.
Vacuum systems reduce flush water volume substantially compared with conventional systems, which directly reduces holding volume required. They cost more and add complexity, but on a boat where tank volume is the constraint they can be the decisive choice.
Shore disposal reality
Plan for what actually exists rather than what should. Pump-out and waste reception facilities in the Labuan Bajo area are limited relative to the size of the fleet, and capacity has not necessarily kept pace with visitor growth. Solid waste and used oil disposal require a working relationship with a shore contractor and a crew habit of separating and landing waste rather than accumulating it. Build these arrangements before you need them — see yard and shoreside logistics.
Design details that decide whether the system is actually used
- Tank level indication that crew can read easily. A system whose state is unknown gets managed by guesswork.
- Tank venting routed so odour does not reach the accommodation or deck spaces, which is the single most common reason crews want to empty tanks early.
- Discharge and pump-out connections accessible and standard, so a shore facility can actually connect.
- Access for cleaning and service, because tanks and macerators need maintenance and an inaccessible tank does not get it.
- Pump redundancy, since a failed discharge pump with a full tank mid-trip is a genuinely bad situation.
- Bilge and oily water separation kept entirely separate from this system and handled properly.
Retrofit is expensive — get it right first
Adding meaningful holding capacity to an existing vessel means finding volume that is currently doing something else, usually fuel, water or accommodation, and it means new plumbing runs through finished joinery. It is one of the least glamorous and most disruptive refit items. On conversions of non-passenger hulls it is a major scope line and it interacts with the certification path — see the refit page and compliance guide.
Requirements are administered locally and do change; confirm current rules with the park authority and harbour master before finalising a design. The full specification chain sits on the specification guide.
Frequently asked questions
Can a yacht discharge sewage in Komodo National Park?
Discharging untreated sewage inside the park is not acceptable and enforcement attention has increased. Vessels need holding capacity matched to guest count and trip length, and in many cases an onboard treatment system, with waste landed ashore where facilities allow. Confirm current rules with the park authority.
How big should a liveaboard’s holding tanks be?
Guests plus crew, times daily production per person, times the days between legal discharge or pump-out opportunities. Liveaboard production is high because guests shower after every dive, so generous watermaker capacity without matching holding volume simply moves the problem.
Should grey and black water be held separately?
Usually yes. Grey water from showers, basins and the galley is produced in far greater volume than black water, so combining them fills a single tank quickly. Segregation allows different handling strategies and stops grey water being forgotten at design stage.
Talk to the build desk
Send the vessel details or the operating profile you want to run and we will tell you what has to be established before a number means anything. Quotations in USD. Construction, repair, refit and vessel-sale contracts are issued by PT Komodo Galangan Nusantara.