Hello folks.I,Koma am the plumber in this chabura, and you are all guilty of “Mishtamesh b’tachsisei malchus. Tsk Tsk. About the basement bathrooms, a quality pump is worth its price, but still has limitations. They are designed to handle the waste, and just toilet paper. Nothing else should be flushed, and kitchen connections and laundry connections are risky because of the grease, and because of lint and the occasional lost sock. In a power outage, obviously it won’t pump, and the average installation can only store two or three flushes. They are also maintenance heavy.
In terms of psak for use on Shabbos, I have seen, in a long career psak from every angle and flavor. My own Rosh paskined not to use them at all, I saw in a RY’s house a shabbos clock with one pin in one pin out (plumbing roulette), in a shul of an adam gadol, there were two canisters, one flowing into the other, and some large mikve sized industrial setups in large shuls and yeshivas where the size made psik reisha a non issue.
The best solution I saw was someone holding by my RY. He lived in a basement and had no choice but to use the pump. He rigged a washing cup on a hinge, with a faucet dripping into it. When full, the cup tipped and spilled into the sink, pulling a string, which by means of small pulleys mounted on the ceiling and floor, pulled the flush handle to flush the toilet. The drip was timed to flush once an hour,and a counterbalance brought the cup back into the fill position. Mi K’amcha yisrael. Just not a conservationist, or EY solution.