@PotteringAlong
I don’t think 11 month old babies need water! Mine were having some with meals at that stage but I never pushed it - milk was by far and away their main fluid.
Also, I don’t think lack of water makes you constipated. More water = more wee, nothing to do with your bowels. I don’t think you will cure constipation by increasing his water intake.
Definitely don’t give your 11 month old squash!
Sorry @ PotteringAlong, but our bowels have everything to do with water, in fact I can't think of anything in the body that doesn't need water to work. Depending on our general health and the weather, an adult can live for about a week with no water coming into their bodies in any form. However, if you were not getting any water you would not want to live for a whole week!
Our bowels need so much water to function that one of the things that would kill you from lack of water would be your bowel seizing up. Constipation is actually when the faeces have had up to almost all their water content withdrawn. If something makes the passage of faeces slow down, the the absorbation of water from the bowel actually increases. In a healthy well nourished human when our stomachs process certain nutrients with the help of stomach acids - the acids break down the food into smaller and smaller pieces so that they can be absorbed by the body. This starts in the mouth with enzymes, and is the main reason (apart from choking hazards) why we should chew all our food thoroughly before swallowing (and why certain tablet medications have enteric coatings which we should swallow whole to stop the digestion process starting in the mouth, and help progress the tablet through the stomach without dissolving in its very strong stomach acids, to the bowel where those particular tablets can then work safely without causing an ulcer to establish in the stomach) - if you have ever vomited you can see, feel (the burn of the acids), and taste the digestion process at work. Anyway, what enters the first part of the bowel is like a thick, mainly liquidised soup, one which during the continued digesting process in the bowel (large and small intestines) leaches out the liquid as it progresses along the bowel. If we get certain viruses, food poisoning, or even a shock, the opposite to constipation happens, as everything is suddenly moved through the bowel at a much faster rate (maybe because the body knows it needs to expell something nasty, and hence maybe why we also vomit - I don't know the working of the body in that much detail as I was a student mentsl health nurse when I learned about the alimentary canal?), and in going so fast hardly any of the liquid (still mainly water based) gets absorbed, leading therefore to diarrhoea, and our anus' can get slightly burned too from any remaining acids. For that essay/exam I didn"t need to cover the bladder as it is not actually part of the alimenary canal, but I think that it must get it's waste water from absorbed liquid.
If you are reading this OP it is not intended to frighten you, if you are still getting plenty of wet (with a pale stain, not a dark one), and normal pooey nappies, then I don't think you have much to worry about, but if you are still concerned then please talk to your health visitor, or if you have noticeably dryer or dark stained nappies, and/or very firm poos, then talk to a Dr straight away.
On a personal note from being a mother of small babies a very long time ago, if your baby does have some dehydration, and you are already giving him a lot of high water content foods, then I would give him any non-alcoholic (obviously) and no-added sweetner, sugar or caffeine drinks that he will tolerate, and then very gradually dilute them until they are mainly, if not solely water - but tjis last paragraph is not due to any medical training, so please don't take that into account. Good luck OP, you sound like a great mum!