JD on Facebook

Installing Blank Vetus Rigid Waste Water Tanks


These instructions apply to the Vetus rigid plastic waste water tanks for grey water and black water.

Grey water tank

A grey water tank should only be used for collecting water from the sink, shower, wash basin,air conditioning, etc..
The capacity of a waste water tank can never be too large.
Match the capacity to the amount of fresh water available; the capacity of the water tank(s).
Fit sink, shower, wash basin, etc. with a drain with sieve, so that coarse waste, such as hair etc., will be less likely to enter the grey water tank.

Black water tank

A black water tank is used only for temporary collecting toilet waste. A black water tank should be installed in accordance with the European Guidelines for Pleasure Boats (EGPB), ISO 8099 Standard.
The capacity of a waste water tank can never be too great.
The capacity should be calculated using the amount of flushing water (outside water) used by the toilet. Reckon on 7 to 14 litres of black water per person per day.
Use only water-soluble toilet paper to prevent unnecessary blockages. N.B: Sanitary towels and tampons in the toilet and black water tank will certainly cause blockages.

Clearing a blockage is an unpleasant job, make sure you have a pair of rubber gloves on board.


Grey water tank
Unpleasant odours will be produced in every grey water tank. Fit the sink, shower, wash basin, etc., with an S-bend (siphon or stink trap) and a plug.
Black water tank
Unpleasant smells caused by faeces will be produced in every blackwater tank. The use of sea water for flushing will increase the smell. The algae in sea water also produce unpleasant smells.
It is possible to add special additives to waste water tanks to reduce the smell, called tank deodorants. A simple way of reducing the smell is by using washing soda, which cleans and sterilizes.
Leaking hoses,hose fittings, tanks, tank covers, etc., can also cause a smell nuisance. So carry out a regular check of the whole system.

For dimensions, see drawing on page 25. Tolerances of +/- 2% apply to all tank dimensions!



The longer waste water remains in the tank, the greater the risk of smell. SO do not leave a waste water tank full unnecessarily. Pump the tank empty once a week, or whenever possible.
The tank can be pumped empty in two ways:
- A 'pump-out' system on the jetty is connected to the tank cap. This will empty the tank out.
- A pump on board the ship pumps the waste water out via the deck cap and a hose connected to it. This pump should have a passage of at least 38 mm (11/2") diameter.

When the tank is pumped empty by a high capacity pump, there is a risk of the tank collapsing due to the under-pressure. This problem occurs especially with 'pump-out' systems.In order to prevent the tank collapsing, one of the following measures can be taken:
- Open the tank inspection cover.
- Open a valve specially fitted in the tank for this purpose.
- Install an automatic relief valve.
- Open the rinse pipe deck cap, if fitted- see page 7 'Rinsing Pipe'.

During your absence

When sinks, wash basins, showers, etc. are not used for a long time, the water in the S-bends, fitted as a smell trap in the drain pipes, will evaporate. This will lead to a smell nuisance. So put plugs in all drains when the ship is not manned for a long time.

Clean and sterilize the tank and pipes at least once a year, preferably at the end of the season.


Grey water tank
Clean the inside of the tank with water and a good degreasing household cleaner. Use a brush or sponge on a rigid tank.
Rinse the tank with clean tap water.
Black water tank
Clean the inside of the tank with water and a good toilet cleaner, use household vinegar when there are scale deposits.
Use a brush or sponge on a rigid tank. Rinse the tank with clean tap water.

Sterilize the tank by filling with a solution of chlorine bleach in water (1 : 1000). Allow this solution to circulate through the waste water system. Remove the solution and rinse tank with clean tap water.



When choosing a place for the tank and for the deck filler cap, take the following into account:
The suction hose should be as short as possible, must go directly down to the tank and be as straight as possible.
The space in which the tank is placed should be properly ventilated.


Instead of just one grey water tank, it is also possible to distribute the total capacity required over two or more tanks.

Arrange the tanks, and thus the weight, evenly over the ship.

(F = Fuel, W = Water, WW = Waste Water)
Install the tank so that it is easily accessible for inspection.
Also ensure that there is sufficient free space over the top of the tank for the hose connections. These must be easily accessible during installation. The tank should be 1 cm. free all round from bulkheads or other tanks, to provide ventilation.
Make sure that the foundation for the tank is strong enough to locate it securely. The tank will increase in size slightly when filled. Take this into account when securing the tank.
Fix the tank in place with the straps from the connector kit, these will accommodate expansion of the tank.

Inspection cover and fittings

Always fit the inspection cover on the top of the tank!
Use the drill stencil supplied to make the hole for the cover. Finish the hole free of burrs.

Drill the holes for the fittings (43 mm (111/16") diameter) and suction tube (57 mm (21/4") diameter) in the top of the tank.
Choose the position of the fittings so that when the ship is beached on its side, waste water cannot run back to the shower, wash basin, toilet, etc., or flow outside via the tank air-relief.

Clean saw dust and drill shavings from inside the tank. Fit the inspection cover in the tank using the gasket supplied. Screw the cover tight against the backing ring using the screws supplied.⇒

Assemble the fittings and the suction tube with the gasket rings supplied. Tighten the nuts using the wrench, never with water-pump pliers.
Do not tighten the nuts excessively.
After 2 days check that the connector nuts are still tight, tighten more securely if required.
Repeat this after 4 days.

To prevent blockages caused by hairs and coarse waste in particular, all fittings should have burrs removed internally, local narrowing should be reduced to a minimum and any changes in pipe diameter should be done using conical adapters or large radii.

Fit the sender for a waste water level meter, if fitted

Tank connections

Connect the tank with a good quality reinforced hose. Avoid sharp bends and kinks or sagging in the hose.

Bracket the hose at not too far apart, regular points, to prevent the hose sagging. Deposits will collect in these sags, causing a blockage after time.

The reinforced hose should be an odour-proof waste water hose and resistant to a limited underand over-pressure of 0.3 bar (0.3 kgf/cm2, 4 psi).
Vetus supplies a hose suitable for waste water.
Article Code:
WWHOSE08, waste water hose, 8 mm (5/16") internal diameter
WWHOSE16, waste water hose, 16 mm (5/8") internal diameter
WWHOSE19, waste water hose, 19 mm (3/4") internal diameter
WWHOSE25, waste water hose, 25 mm (1") internal diameter
WWHOSE38, waste water hose, 38 mm (11/2") internal diameter
Specially for black water tanks: SAHOSE25, odour-proof waste water hose, 25 mm (1") internal diameter
SAHOSE38, odour-proof waste water hose, 38 mm (11/2")internal diameter.

Fit every hose connection with a good stainless steel hose clip.

Install pump '13' and hull outlet with valve '15'.

Install the suction hose(s) '21' and/or '22' (38 mm. dia.) such that neither the tank, pump or deck cap are subject to any mechanical loads.

Fit the air-relief nipple '18' as high up as possible above the level of the top of the tank. Choose a place for the nipple where rain or other outside water cannot enter. If required, fit an odour filter '19' between the airrelief pipe and nipple.

Fit the air-relief pipe '23', internal diameter 16 mm (5/8"), 25 mm (1") or 38 mm (11/2") between the air-relief nipple and the tank. When viewed from the tank, the air-relief pipe should run straight upwards.

Discharge pump

A non-priming waste water pump must be fitted lower than, or at the same height as the underside of the tank.
A self-priming pump can be mounted at any height in relation to the tank.

Install a bend ventilator '14' in the discharge pipe between pump and hull outlet when the waste water tank is below the water line and the hull outlet is also below the water line.

Rinsing pipe

In order to rinse out the tank easily with clean water, and extra fitting can be made in the deck connected to an extra deck cap. Clean water can be poured in through this pipe.

Preparation for winter

The tank, pipes, pump, etc., should always be drained.
Never add anti-freeze to the tank or other parts of the waste water system to protect against frost damage. Anti-freeze is very poisonous!
Clean the tank according to the cleaning procedure.


Regularly check the air-relief nipple and clean its sieve if necessary.
Regularly check the hoses and hose connections for possible leaks and fit new hoses and/or hose clips when necessary.
Also check the tank for damage caused by abrasion. Replace a damaged tank immediately.
At the end of the cruising season, carry out the cleaning and sterilizing procedures as described under 'Use'.
A tank and installation which is seriously polluted with algae can be cleaned by thoroughly rinsing out the tank, pump and pipes with chlorine.

Technical Data

Rigid waste water tanks for grey water/black water

Capacity: 42 61 88 110 137 170 215 litres *)
9.2 13.4 19.4 24.2 30.1 37.4 47.3 Imp.gal.*)
11.0 16.1 23.2 29.0 36.2 44.9 56.8 US gal.*)
Weight: 3 4 6.7 7.5 9.25 11.4 13.6 kgs *)
6.6 8.8 14.8 16.6 20.5 25.2 30.0 lbs *)
Max. Pressure: 30 kPa (0.3 bar, 4 psi)
Material : Polyethylene, colour: black

Hose fittings : For grey water tanks/black water tanks
For filling hose : 16 mm, 25 mm, 35 mm and 38 mm dia.
5/8", 1", 13/8" and 11/2" dia.
For discharge hose : 38 mm (13/8") dia.
For air relief : 16 mm, 25 mm and 38 mm dia.
5/8", 1" and 11/2" dia.
Fittings for hose
with suction tube :
For grey water tanks/black water tanks
For pump connection : 38 mm (13/8") dia.
For Vetus waste water deck cap : 38 mm (13/8") dia.

*) Nominal values are given for capacity and weight. Slight deviations are possible.

TotalBoat Blogs Live Tech Support