This is so upsetting to read. Your son deserves to be cared for properly, to feel safe, be nourished and have a calm peaceful home in the care of people who love and cherish him.
The screaming, banging around, missed meals, no water, shit tip surroundings and stressed, angry, resentful, neglectful father are dangerous. He’s a small baby. His needs are so simple and to hear they’re not being met and he’s around so much horrible drama is appalling.
You know you’re making excuses for him. Have you ever forgotten to give your baby a drink? Why not? If you did wouldn’t you feel traumatised by guilt? You’re annoyed and concerned but you’re minimising the extent of his utter failing and still expecting too little.
Please leave him. Do whatever you have to to get your son and yourself safe and away from him. You need to tell someone, HV, GP, nursery, what’s going on so there’s a record somewhere of what he’s been like.