As a landlord, I agree that your landlord should ensure the plumbing is in proper working order at the time you rent it. If however it becomes clogged after you rent it, its actually your responsibility. And the sump pump is just like your stove, its the renters job to ensure he operates it properly. On the flip side of the coin, its the landlords property, a long term investment. It should be in his best interest to make sure you are informed of the proper operation of the pump and also make you aware of any past clogging issues due to leaves and such so you know what to look out for. That being said, I usually take care of plumbing issues on my dime, simply because I dont want an un-qualified person messing with my plumbing. You may find your landlord isnt as worried about his place and hasn't told you these things or he didnt know himself. But anyway, I hope your stuff isnt damaged badly and I hope your landlord feels some responsibility if he realizes he didnt inform you properly. I know I would and I would do my best to help you out, had I not properly informed you..... Good luck though, either way!