Is it permissible for a husband to continue his work in a company that purifies water, knowing that the purified water will be used in a factory for producing beer, and if he leaves the job, he will be fired?

It is not permissible to assist in drinking alcohol in any way, due to the hadith: "Allah has cursed alcohol, its drinker, its server, its seller, its buyer, its presser, the one for whom it is pressed, its carrier, and the one to whom it is carried." Working on establishing a unit to supply a factory that produces intoxicating beer is considered assisting in drinking it. Therefore, it is not permissible for your husband to work on establishing this unit, and he must request a transfer to another permissible job. "And whoever fears Allah – He will make for him a way out and will provide for him from where he does not expect."