I'm on a roll 
Here's the info about water and why it's so important, which is from the FAQ thread (here: https://www.mumsnet.com/talk/low_carb_bootcamp/4049535-Low-Carb-Bootcamp-FAQs?reply=118903269:
14. Why is water so important?
When your body stores carbs, which is what is happening when we eat a high carbohydrate diet, it holds onto water. For every 1 gram of carbs you store, you’ll store an average of 4 grams of water. Once these carbs are removed from your diet, water will come along with it, so it’s important to maintain proper fluid levels when you’re low carbing. Dehydration can make you feel quite poorly, making you feel tired, as if you’re going down with something, and can lead to headaches.
15. Why you should drink more water when low carbing
Your body goes through major metabolic transitions as you become a fat burner. Here’s why adequate fluid levels are crucial:
1.you need to replace lost water
As mentioned previously, your body stores water when carbohydrates are present. When carbs are eliminated, water is also flushed out.
2. it curbs cravings and regulates appetite
Often, when you experience hunger pangs or sugar cravings when you’re low carbing, it’s most likely because you’re dehydrated. Make it a habit to reach for a glass of water instead of a sugary treat when these cravings arise.
3. it puts less stress on your kidneys
Ketones are acidic and some of these ketone bodies are flushed out instead of used for fuel to ensure they don’t accumulate in the body. Drinking more water supports the kidneys’ role of filtering out any unnecessary toxins that may be lingering.
4. water helps fat metabolise faster
The process of beta oxidation (where fats are broken down) requires water molecules. Burning fat costs more water during the process compared to carbs which means more water consumption will help your body break fats down more effectively.
(adapted from //www.carbmanager.com)
Finally, one other benefit of keeping your water intake up is that it helps to prevent constipation!
16. What counts towards my water intake?
Ideally, just plain water! However, that can get boring quickly, and other fluids will clearly help to keep you hydrated, so you can include tea and coffee – just be aware that if you like milk in your tea and/or coffee, you can very quickly rack up a lot of carbs. So try, as far as possible, to drink them black. Remember there’s also caffeine in tea and coffee, so it is preferable to aim to get your water intake mainly from plain water.
If you find plain, cold water boring, try adding slices of lemon or lime, or cucumber – or even fruit like strawberries or raspberries (just don’t eat them!). Sparkling water adds texture which can make it more interesting, and there are lots of flavoured waters on the market too – just be careful to avoid those that contain sugar and sweeteners.
There are also many cold fruit infusions on the market now, as well as fruit and herb teas if you want something hot.
As well as cold water, try drinking it hot– it’s very soothing, and lovely with a slice of lemon and/or ginger.
17. How can I make sure I drink all the water I need?
If you have a lot of weight to lose, you’re going to need to drink a lot of water, and that can seem really daunting. But if you spread it through the day, it will be easier.
Some tips:
• drink a couple of glasses of water as soon as you wake up. Your body is most dehydrated after a full night’s rest, so drinking water as soon as you wake up is a great way to start your day hydrated.
• buy a new water bottle if you don't have one, or perhaps a nice glass. Figure out if you prefer large glasses or if that actually over-faces you. Perhaps a small one topped up by a bottle is better for you?
• if you’re sitting at a desk all day, make sure you always have a bottle of water on the desk
• try the elastic band trick – let’s say you have to drink 4 litres of water per day. Break that down into a smaller number of glasses, e.g. 8 x 500cl glasses. On your water bottle, put 8 elastic bands. Each time you finish a glass of water, take one of the elastic bands off.
• try using a hydration app – for example Waterlogged; you can photograph all your different bottles/mugs/glasses in regular use and add their sizes and log as you drink