Agree with above with regard to weights and carrying 125 litres of water. That's a couple of adults in the back.
However, I doubt that your handbook or door pillar will give you a payload for your car as someone else has advised.
During the time I worked for Citroen, all payloads for vans were freely available, but not for the Berlingo Multispace. I had to contact the factory's technical dept for that info.
The Citroen Berlingo van in those days was 600 or 800 kgs but the Multispace was about 450kgs (drivers weight and full tank of fuel considered.) The suspension was 'softer' so it gave a more comfortable ride, hence the lower carrying capacity.
Is see that the Peugeot 206 panel van has a payload of 526 kgs which I am very surprised about (driver and fuel weight will reduce that), but the car won't be as much as that.
Spruce