One of the most important point to consider when installing pump to your existing water lines is whether the plumbing is strong enough to withstand the pump's pressure. Although the pump have auto pressure sensing ie auto off, it may exert very strong pressure just before shutting down and that will cause havoc- causing leaks - worst still if the joints are inside the walls!

Leaks also cause the pump to run intermittently as pressure drop. Another problem is WC toilet has a very simple/fragile stop valve, a few drips is common even when wc is already full, but the pump will be sensitive enough to sense a pressure drop and again you have the pump running - and during midnight , it can be annoying.