If you have renter's insurance, it should pay to put you up in a hotel. If you don't have it, get it. It's only around $15/month. Make sure it has a clause where the insurance will pay for your displacement costs (hotel, etc.) if you have to move out temporarily. I have this in my renter's insurance, up to $3,000, and my renter's insurance is only $15/month.
Otherwise, if you can afford to move into a hotel temporarily, do so, and inform the landlord you expect him to pay for it until you and your child can live in place that is not flooded with sewage (and use those words).
Take photos.
Generally, if the issue is a habitability issue, the landlord has to fix it asap. If he gets it fixed in a couple days, that would probably be fast enough according to the courts. Especially if he could show he couldn't get anyone out to fix it for a couple days. But, the court might make him pay for your hotel room.
To get your deposit back, you'll probably have to do it right - tell the landlord about the problem, give him the appropriate time to fix it, etc., before you can terminate the lease without penalty. Here's the link to the laws that were mentioned by someone else above:
http://www.peoples-law.org/special-landlord-tenant...