Grey / Black water holding tank capacity

[markspark7]

I have two 600 litres clean water tanks with a single point to fill them, both tanks are connected underneath so get 1200 litres in total.
I have however got no holding tank for grey black water . If I fit a holding tank what size would you recommend be fitted?? is there any official size based on clean water??

Big lazerette so space is not a problem.

Cheers in advance

 

[TonyR123]

I have 640 litres of water and 120 litres for black water (so only toilets go in this). Next boat I would want over 1000 litres for water and at least 200 litres for black water - maybe more. I probably have to empty black water every 3 days at best with 6 on board.

 

[jrudge]

I have 1000 ts and 200 lts of black water. That lasts a week with 2 of us on board and 3 days with a full boat.

 

[vas]

500 and 110 respectively. With 6+ up, black barely makes it 2 days, with 2up can do a week. Have a watermaker, so freshwater tank size doesn't mean much tbh

 

[Boater On Thames]

I have 100 gallon fresh water tank, 40 gallon black water tank.

 

[markspark7]

I'm looking to go to the Med at some point, is there a minimum requirement for how much black water I should be able to hold?

 

[jrudge]

No. Greece has ( I believe ) strict black and grey water regs but no one else
Many older or sail boats don’t have a tank at all. People also discharge at night into the marinas. You can tell as a boat with people on it that does not move for 4/5,days has no other option. Most marinas in Mallorca do not have pump out. I cannot name a single one.

 

[jrudge]

European Black and Grey Water Regulations | Noonsite