Somehow this just appeared in my notifications. Not sure why so late...sorry.

They have him tablets, and he mixes his glasses of water, about three a day, plus tea, etc, with some salted tomato juice to make the water more appealing.

Your husband will need monitoring. It's not enough for him to take sodium tablets in perpetuity and not know if his blood pressure rises as a result, or if he's getting too little. I would urge you to ask for a two-month follow-up, and than another at six months just to keep tabs on his levels.