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Vetus Waste Water Tank System Installation


These instructions apply to the Vetus waste water tank system for black water.

Black water tank

A black water tank is used only for temporary collecting toilet waste.
A black water tank should be installed in accordance withe 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.


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.

Tolerances of +/- 2% apply to all tank dimensions!



Always empty the tank in accordance with environmental regulations.
There are some regions where direct discharges into the outside water are forbidden.

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 day, 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.
- The tank pump can be used for directly pumping out waste water overboard, provided it is lawful to do so.

The pump has a bore of dia. 38 mm.
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.
- Install a 38 mm dia. ventilation pipe.

After pumping the tank empty:
Rinse the tank with clean water, so that all the discharge hoses are filled with clean water.

During your absence

Flush the toilet several times to ensure the hose linking the toilet and the tank is filled with clean water to avoid smells when not in use.

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


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.


Several toilets may be connected to a single tank. Extra fittings are also available.

Position the tank as close as possible to the toilet to avoid dirty water flowing back into the toilet from the tank when the boat heels.

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

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. Attach the tank using the stainless steel rings supplied.

Inspection cover and fittings

The inspection cover and the fittings are pre-assembled in the upper section of the tank.

Use the tool provided to fit the fittings in the correct direction.

If required create additional holes on the top of the tank for extra fittings (43 mm dia.). Choose the position of the fittings so that when the ship is beached on its side, waste water cannot run back to the toilet, or flow outside via the tank air-relief.

Clean saw dust and drill shavings from inside the tank.

Assemble the fittings 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.

The sensor for a dirty water level meter is already fitted in the top of the tank.
The sensor can be connected only to a Vetus level indicator for waste water.

Option: Vacuum operated vent valve VRF56
In the top of the tank, drill the hole for the vent valve (dia. 57).

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:
   Specially for black water tanks:
   SAHOSE16, odour-proof waste water hose,
   16-mm (5/8") internal diameter
   SAHOSE19, odour-proof waste water hose,
   19-mm (3/4") internal diameter
   SAHOSE25, odour-proof waste water hose,
   25-mm (1") internal diameter
   SAHOSE38, odour-proof waste water hose,
   38-mm (1 ½") internal diameter.

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

Attach the discharge connection '5' to waste water pump '9'.
To assemble the valve correctly, consult the waste water pump manual.

Install hull outlet with valve '11'.

Install the suction hose '17' (38 mm. dia.) such that neither the tank, pump or deck cap are subject to any mechanical loads.

Fit the air-relief nipple '14' 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 '15' between the air-relief pipe and nipple.

Fit the air-relief pipe '18', internal diameter 16 mm (5/8"), between the air-relief nipple and the tank. When viewed from the tank, the air-relief pipe should run straight upwards.

Install a bend ventilator '10' 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.

If the suction connector '3' is not being used, close the suction pipe off with a plug.

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!
anti-freeze may be used.
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

Waste water tank system

Type : WWS42 WWS61 WWS88 WWS120
Capacity : 42 61 88 120 litres *)
9.2 13.4 19.4 26.4 Imp.gal.*)
11.1 16.1 23.2 31.7 US gal.*)
Weight : 12.5 14 16 18 kgs *)
28 31 35 40 lbs *)
Max. Pressure : 30 kPa (0.3 bar, 4 psi)
Material : Polyethylene, colour: black
Hose fittings
For filling hose : 38/35/25/19/16 mm dia.
For discharge hose : 38 mm dia.
For air relief : 19 mm dia.
For discharge : 38 mm dia.

Fittings for hose with suction tube
For Vetus waste water deck cap: 38 mm dia. (1 ½" dia.)

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

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