Sorry you're going through this. Can you tell if the water is dirty? If it has come through a ceiling in the UK it would be likely to be. If it is and you don't want it to stain, you need to clean whatever has got wet. It maybe that staining isn't that important in the big picture.
Air flow is your biggest friend in this situation. Open all windows and doors, pull anything like curtains out of the way. If you have a fan and electricity and can afford it, then aim the fan at things and keep moving it.
Wipe down all wood etc as best you can and anything seriously wet try and get closer to the window/s and if possible sunlight.
Fabric sofas chairs or chair pads; dry out manually by squeezing against towels, and again get as close to windows and direct sun as you can.
Wiping with a VERY MILD (very mild is capitalized) bleach solution will help prevent mold and doesn't have to use more than a cup of water if it isn't too precious for that use.
I have never been to Greece (sadly) but live in multi culture land including a Greek/Turkish Cypriot community and lots of tinned and jarred Greek food. I'm vegetarian so a bit limited, but I believe there is a specialty chicken soup in tins.
I am assuming a language problem and or lack of help in supermarkets, as well as visual issues, so if not forgive me for writing this with that assumption.
When water is scarce, lick your plates and any pan used for sauce, clean, before wiping! A spatula can be used to remove as much oil etc as possible.
If you can get loo roll and kitchen paper, do. I would also in your position look for cling film and plastic bags, including dog poo bags and disinfectant. If your toilet isn't working plentiful supplies of newspapers and bags are going to become important.
Wine would be my first go to, assuming you mat be able to get it- you can cook a great deal in wine, as well as just drink it and thank the Gods!
I'm not aware of our Greek supermarkets here having cider, but it will also do nicely for cooking. I've never tried beer.
Pasta, rice, and potatoes, if you can get any, can all be cooked in wine. The trick is to heat it to nearly boiling and with a lid on simmer at low heat. Breaking up pasta, crushing rice, and very thinly slicing potatoes all help with cooking with limited fluid.
You can also, once simmered a bit, take the pot off the stove and wrap the pan in if possible foil first, a large towel or anything similar, and it will continue to cook and soften, (If you have a heavy duty cooking pot it is particularly effective) if your capabilities allow it.
The texture may not be perfect but after you've made the sauce from the wine, you really wont care. You do need to balance out any alcohol content with food or you will speed up dehydration.
Rose water tends to be small bottles but it is cheap and may have been overlooked in any scramble.
Tins of stuffed peppers and stuffed vine leaves, okra, chicory, onions dishes, spinach giant beans, and aubergine come in tins about 3 to 4 inches high, by 5 to 6 wide. Many are in a sauce. Add any sauteed fresh veg you can get to them.
Most foods I have found in these sized tins are vegetarian. However I believe fish may also come in similar tins. I do know there are small flatish oblong ones that are sardines, and similar but with rounded corners are likely to be mackerel or herring.
If the shelves haven't been cleared out, I'd also expect to find peppers, olives, capers, vine leaves and other vegetables, and sun dried tomatoes, in jars with fluid which can be used as a base for a sauce and liquid intake. Beware of mistaking tomatoes with jars of chili!
Tomatoes, are usually in oil, vine leaves and peppers may be in oil or vinegar, the rest are usually vinegar. Sugar and a little orange juice, or even honey or marmalade added to any vinegar solution, will give you a basic sweet and sour liquid to cook in or make into a sauce if you have flour, or you can reduce fluid by cooking.
Stale bread can be dried and turned to crumbs and used to bulk, or ground down to a form of flour replacement.
Rice can be cut and crushed and also ground down.
Tinned chick peas and butter beans and similar, you can mash finely and add tahini and preferably lemon or lime juice to them, to make hummus, which will also add fluid to your intake.
Six sided jars are likely to contain sweet preserves. You can use them as a sauce base with vinegary fluids.
I hope the supermarkets aren't bare, and this is some use.