Grey and black water tanks

[keithgdg]

I am currently designing my grey and black tank system for cruising next year. I can find lots of info about fittings, pipe runs, Y valves, and the like but very little about tank sizing. I have a long encased keel so capacity storage space is not a problem. Anyone any tips on tank sizing????

 

[Bertramdriver]

Have a look at Vetus on line shop. You can tank until you drop!

 

[Tranona]

I am currently designing my grey and black tank system for cruising next year. I can find lots of info about fittings, pipe runs, Y valves, and the like but very little about tank sizing. I have a long encased keel so capacity storage space is not a problem. Anyone any tips on tank sizing?������

As big as you can! Minimum is 4l per person per day for black. So a 30l tank will just do a weekend for 2 people if you use it all the time. So, the larger your tank, the more independent you are of pumpouts or offshore discharge. Clearly you have to think of ways on minimising your use as well. You will need a pumped system if you are putting the tank in the bilge and you stand a chance of getting good capacity. Downside is probably lots of pipework. modern boats with shallow bilges often end up with space for only a miserly 60-70l! Good information on the Tek Tanks and Lee Sanitation sites.

 

[tri39]

Do you really want a large sewage tank in the bilge?! Where are you intending cruising? A small one with gravity drainage if poss is more like it.
Anecdotal evidence suggests that while many boats fit tanks, very few use them!

 

[RobbieW]

We have a 100l black tank used for #2s, #1s go through the other heads. For 2 people that really needs emptying every 5-6 days. Lavac head if that makes difference

 

[vyv_cox]

Grey tanks. The proposed insistence upon them by Turkey seems to have come to nothing. I have not heard that they are required elsewhere. For guidance, in motorhomes the grey tank is somewhat bigger than the total fresh water capacity, fairly logical. The biggest problem with them is that they become clogged with grease/fat and hair, mixed with bits of cooking or washing up debris, especially rice, which all requires removal from time to time. A large inspection hatch would be a good idea. On motorhomes they drain by gravity but you would need a pump that can cope with all sorts of solids, so a large diaphragm one seems most logical. A Henderson as used with a Lavac?

 

[charles_reed]

5 - 8 litres/day/person.
Most of the volume is flushing water, so having a handy changeover valve is a good idea.