How can we stop water from seeping through the walls of the cold room?

If it’s any consolation, you have a pretty common problem. It may be necessary to have the soil dug out around the foundation and extensive work done to stop the water, but before you go to this kind of massive trouble and expense, I have a suggestion.

According to Consumer Reports testing, a product called Drylok is a very effective waterproofer for use inside masonry walls. It tested far better than anything else, so don’t be discouraged by your lack of previous success with paint. From what I’ve seen, I expect Drylok will solve your problem. You do need to get back to bare masonry before applying it, though. You’ll also need to put the product on when the concrete isn’t oozing water. Lots of places sell Drylok, though many store clerks don’t know it. Ask them to do a computer search before they dismiss your request.