OP please please listen to the people saying don't have a child with him, and to leave him.
He thinks he gets a say in your private medical decisions and pain management!?
Even if you manage to get to a resolution on this issue, I would seriously reconsider building a life with someone with completely opposing views to me, that doesnt listen even when the issue affects me a million times more than it affects him.
Where and how to give birth is one of thousands of decisions you make as parents, and they only get more difficult as your children get older. Can you imagine if you have different views on something like breastfeeding, say if it didnt work and was extremely painful and you and the baby were suffering because he thought it was best for the baby so you should persevere (or you wanted to but he was against it for some reason). Or he thinks the baby should 'learn to self soothe' at a few weeks old and is adamant you leave them to cry when you know they actually really need feed and comfort? Or if he believes that physical punishment is the best way to discipline?
If he has an opinion that's different to you and you think his way of doing things is going to hurt your child, I promise you it's actually much worse than if you disagree and you think his way might hurt yourself.
If you insist on pro creating with someone who is ill informed, stubborn, arrogant, and doesn't give a shit about your opinion or health or best interests, then I'd advise going to NCT or visiting your local maternity ward.
For what it's worth you dont need to give birth in water, you can just labour in there if you want, but only a minority of people actually manage it (only very straightforward and relatively quick labours qualify and there are relatively few pools available at any one time normally). There are advantages and disadvantages (including labour often slows down in the water). I spent part of my labour in the water, and the pain relief aspect of it was amazing - I found it much more effective than gas and air.
Lastly you might want to bear in mind that one of the main factors in PND is an unsupportive or abusive partner