I don't recall the exact numbers but I was given a program - based largely on my weight. It was an increase in intake over a period, not just a bunch starting at once... I forget if there was a cutting back day or not. Worked well though.

I've heard you can go to some naturopaths (maybe docs too) that will help you rehydrate with an introvenus (spel?)

I certainly wouldn't drink straight water to rehydrate - if nothing else I'd make a home made "sports" type drink... I'd have to research it but I would at minimum add unprocessed sea salt if nothing else for some electrolytes, likely some raw sugar or a bit of fresh squeezed juice.

"clean" water (city, demineralized etc) in the loading as well in rehydrating is a problem because without trace minerals (eating fruit helps too) your water to electrolyte balance gets out of wack and this is very very important to the body. If there are not enough electrolytes in relation to the water the body won't hold onto the water because its dangerous without the electrolytes. So to hydrate, and get the water in it helps loads to have some trace minerals.

Unprocessed sea salt and/or a squeeze of lime helps with the mineral content as well as positively adjusting the pH levels etc etc (salt is also very important on hydrating on a cellular level)

So in loading you want to to stay in and obviously in re hydrating... something to look at in my opinion.