u can first break fast with water then eat later noproblem on parana day of ekadasi fast

 If one finds himself in difficult circumstances and cannot break the Ekadasi fast properly on Dvadasi, one can break it by drinking water, and then one is not at fault if he eats again after that.

https://iskconreading.org/utpanna-ekadasi/

one may break the fast at the right time by drinking water if eating is difficult to arrange.

https://www.salagram.net/ekadasi-page.htm#Ekadasi%20Meditation

If you have observed a complete fast (without even water), you do not need to break it with grains. 

You can break it with caranamrita or fruit. 

Those devotees who fasted all day and took nothing other than air, it is advised to drink a mixture of 50 - 50 hot milk and water, sweatened with rock candy sugar after the sun has risen at the appropriate time.

The effects of this loosen the mala (stools) in the intestine where all the toxins from the fast have been absorbed, and expell it all within about half an hour. 

Then take a light lunch, eating only once on the dwadasi. ither way, this is also a good reason to expell the toxic waste malas (stools) collected in the intestine, this is done on the dwadasi morning with the aide of the sweet nectar mixture of hot milk and water of a ratio 50/50 and very sweet with rock candy (yellow lump - available Chinese stores) after sun-rise. 

If one has fasted completely there's no point in trying to pass when one first rises, as we normally do as there will be no issue due to no intake of food or water on the previous day. 

However, half an hour after taking the drink the mallas will be expelled from the body https://www.salagram.net/ekadasi-page.htm#Mahadwadasi. KAmikA EkAdasii - from BrahmA Vaivarta PurANa: https://www.salagram.net/ekadasi-17.htm about each ekadasi https://www.salagram.net/ekadasi-16.htm