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Installing Vetus Rigid Waste Water Tanks with Connection Kits


This manual is for the Vetus (rigid) plastic waste water tanks (for 'gray water' and 'black water'). See the drawings on page 28 for dimensions. Tolerances of + or - 2% apply to all dimensions!

These tanks are made from low pressure polythene and therefore have the following properties: they are algae resistant, hardly any condensation is formed, the material is insulating, the surface is very smooth, the plastic is indestructible and very environmentally friendly and there are no electrolysis problems.



The longer polluted water has been in the tank the greater the risk of nuisance from smell. Therefore, never leave a waste water tank filled unnecessarily long, but pump the tank empty or have it pumped empty once a week, or whenever possible. Pumping empty can be done in two ways:
  1. by connecting a shore pump-out system to the deck cap to pump the tank empty.

  2. by using a pump present on the ship to pump out the waste water through the deck cap and a hose connected to this. This pump must have internal diameter of minimum dia. 38 mm (1½ inch).

If the tank is pumped empty by a high capacity pump there is a risk of the tank collapsing due to the reduced pressure caused. This problem occurs particularly when using the pump-out systems. The following measures can be taken to prevent collapsing from occurring:

  • open the inspection cover on the tank
  • open a shut-off valve fitted to the tank for this purpose
  • install an automatically working blow valve.

During your absence

The water in the siphons can evaporate when no use is made of washbasins, showers etc. for a long time (siphons act as smell traps in the pipes). This causes smell nuisance. Therefore, place plugs in all drains when the ship is not to be manned for a longer period.

Disinfect the tank and pipes at least once a year preferably at the end of the sailing season.


'Gray water' tank
Clean the inside of the tank with water and a good degreasing household cleaner; use a brush or a sponge for 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; add cleaning vinegar if there are lime deposits; use a brush or a sponge for a rigid tank. Rinse the tank with clean tap water.


Disinfect the tank by filling it with a solution of bleach in water (1: 1000). Circulate this disinfecting mixture through the waste water system. Remove the solution and rinse the tank with clean tap water.

'Gray water' tank

A 'gray' water tank is only to be used for collecting water from a sink, shower, washbasin, air conditioning, etc. and not for toilet waste. The capacity of a waste water tank can never be too large. Choose the capacity of the tank to suit the quantity of fresh water, that is the capacity of the water tank(s). Fit a drain with a sieve to the sink, shower, washbasin etc, so that as little as possible coarse waste such as hairs and similar can collect in the tank.

'Black water' tank

A 'black' water tank is to be used exclusively for the temporary collection of toilet waste. In order to comply with the European Recreational Craft Directive it must be possible to see the quantity of "black water" in the tank from outside of this or a float must be fitted that is connected to an indicator positioned in an easily accessible place. A "black water" tank must be installed in accordance with the European Recreational Craft Directive (ERCD), standard ISO 8099.

The capacity of a waste water tank can never be too large, and must be geared to the quantity of water used (external water) to flush the toilet. Allow for 7 to 14 liters (2 to 4 Gallon) of black water per person per day. Only use toilet paper that will dissolve in water in order to prevent unnecessary blockages from occurring. N.B. Sanitary towels in the toilet or "black water" tank will inevitably result in blockages!
Solving blockages is an unpleasant task. Make sure that you have a pair of rubber work gloves or surgeon's gloves on board.


'Gray water' tank
Unpleasant smells are produced in all 'gray water' tanks. Fit the sink, shower, washbasin etc. with a siphon (smell trap) and a plug.

'Black water' tank
Unpleasant smells are produced from the feces in all 'black water' tanks. The amount of smell produced is increased by the use of salt water for flushing (because of the algae present in salt water). Special substances, so-called tank deodorants, can be added to a waste water tank if necessary to reduce the smell. A simple way of reducing the smell is to use soda that both cleans and disinfects. Leaking hoses, hose fittings, tanks, tank cover etc. can also be the cause of smell nuisance. Therefore, carry out regular checks of the complete system.



Take the following into account when choosing a position for the tank and the deck filler cap: the filler hose must be as short as possible, must slope down continuously from the deck cap to the tank and must be as straight as possible. There must be sufficient ventilation in the space in which the tank is positioned. The height difference between the tank and the filler cap may a maximum of 2 metres (6'8") (the maximum excess pressure in the tank is 0.2 bar (3 psi) !)

Tank fittings
Spare parts (supplied with the tank) The inspection cover with backing ring is already fitted in the tank.
Fitting spanner
Position the fitting using the spanner supplied. Never use a pipe wrench.

Suction pipe
The suction pipe with right-angled fitting is also already fitted in the tank.
Float for a tank gauge sender
The tank is prepared ready for rapid fitting of a float connected to a tank contents sender with SAE cartridge (see page 9 for a summary of float and meters).
Fitting the filler pipe
A hole dia. 42 mm (1 5/8) is already made in the tank for the input of waste water (4). See page 9 for the correct fitting for the chosen filler pipe diameter. See the drawings on page 28 for the main dimensions of the fittings.


Position the tank in such a
way that it is readily accessible
for inspection. Also make
sure that there is sufficient
free space
above the tank
for the hose connections.
These must be easily accessible
during fitting. There
must be free space with no
bulkheads or other tanks of
about 1 cm ( 3/8" ) all round
the tank to allow ventilation.

Ensure that there is a sufficiently
solid foundation for
placing and fixing the tank
The size of a tank increases
slightly when it is full.

Take this into account when
fixing the tank in place.

Fitting in sailing ships
When fitting remember that the filler
hose must always be positioned
on the same side of the ship as the
This prevents too high a pressure
from possibly occurring in the tank
when sailing at an angle.

Connecting the tank

Use good quality hose to connect the tank. Avoid sharp kinks or sagging in the hose when doing this.

Support the hose with brackets at regular distances not too far apart. Sediment will collect where the hose sags and can lead to blockages after a time.

The reinforced hose must be a smell-proof waste water hose and at least resistant to a small increased or reduced pressure of 0.3 bar (0.3 kgf/cm2) (4,2 psi).

Vetus supplies a hose that is suitable for waste water. Use a good quality stainless steel hose clamp for all hose connections.

Install the pump '13' and the hull lead-through with shut-off valve '15'.

Install the suction hose(s) '21' and/or '22' dia. ( 38 mm) (1½") in such a way that neither the tank, the pump nor the deck cap is mechanically stressed.

Fit the vent nipple '18' as high as possible, above the level of the top of the tank. Choose a suitable place for the vent nipple so that rain or water from outside cannot penetrate. If desired fit a smell filter '19' between the vent pipe and the vent nipple.

Fit the vent pipe '23' internal diameter 19 mm (¾"), between the vent nipple and the tank. The vent pipe must be fitted so that it is continuously sloping upwards as seen from the tank.

Suction pump

A non-self-priming waste water pump must be positioned lower than or at the same height as the bottom of the tank. A self-priming waste water tank may be positioned at any height relative to the tank.

Install the bend aerator '14', in the discharge pipe between the pump and the hull lead-through, if the waste water tank is positioned below the waterline and the hull lead-through is also below the waterline.

Rinsing pipe
In order to be able to rinse out the tank easily with clean water an extra fitting can be made in the top of the tank that can be connected to an extra deck cap through which clean water can be added.

Fit a discharge hose A, internal diameter 38 mm ( 1½" ), between the deck cap (5) and the tank. Install this hose so that neither the tank nor the deck cap is mechanically stressed. Take the maximum excess pressure of 0.2 bar (3 psi) into account; i.e. the filler cap may not be fitted more than 2 meters (6' 8") higher than the tank.

Fit the vent nipple 1 as high as possible above the level of the top of the tank. Choose a suitable place for the vent nipple so that rain or water from outside cannot penetrate.

Fit the vent pipe B, internal diameter 19 mm, between the vent nipple (1) and the tank connection (2). It is very advisable to fit a smell filter type NSF19 in the pipe. This prevents unpleasant smells from the vent nipple.
The vent pipe must be fitted so that it is continuously sloping upwards as seen from the tank.

Making ready for winter

The tank, pipes, pump etc. must always be drained completely. Never put anti-freeze in the tank or other parts of the drinking water system to protect it against freezing, anti-freeze is very poisonous!


Check the vent nipple regularly and clean the sieve of the vent nipple if necessary. Check the hoses and hose connections for possible leaks annually and fit new hoses and/or hose clamps as necessary.

Also check the tank for damage as a result of chafing. Replace a damaged tank immediately. Carry out the disinfection procedures described under 'Use' at the beginning of the sailing season; see page 6. A tank and installation that is strongly contaminated by algae can be cleaned by rinsing the tank, the pump and pipes with chlorine water.

It is advisable to grease the seal with Vaseline on both sides at every service.

Scope of delivery

- 1 rigid waste water tank (40, 60 or 80 l)
- fitting connection dia. 19 mm ( ¾ ") for vent hose
- suction pipe with fitting connection for dia. 38 mm (1½") hose
- inspection cover with counter ring
- 2 fixing belts
- fitting spanner

Technical details

Material of suction pipe: Pa 6
Right-angled fittings: 360° rotating
Capacity: 40 l (8,8 Imp.gal, 10,6 US.gal),
60 l (13,2 Imp. gal,15,9 US gal),
88 l (19,4 Imp. gal, 23,2 US gal)
Wall thickness of tanks: 7 mm ± 1.5 mm (¼ " ± 1/16")
Material of tanks: LLDPE

(Linear Low Density Polyethylene) foodstuffs quality Maximum permitted pressure: 1.2 bar (17 psi)

Properties of LLDPE:
algae resistant
hardly any condensation (important for fuel tanks)
insulating material, very smooth surface
indestructible plastic
most environmentally-friendly plastic
has no electrolysis problems unlike stainless steel

Dimensions of fittings:

  • Suction hose: dia. 12 mm ( ½ ")
  • Vent hose: dia. 19 mm ( ¾ ")
  • Filler hose: dia. to be determined by user (i.e. dia.16 (5/8 ") , 19 ( ¾ ") , 25 (1 "), 35 (1 3/8") or 38 mm (1½")

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