So ganas...   

People probably don't mean to sound like a herd of elephants; they just don't know it's a problem. Talk to them... or if paiseh leave them a polite note on their door (minus red paint) 

The noise is part and parcel of living in condos and other high-rises, your ceiling is somebody's floor.

Options available:-

Aggressive Approach

1) Tell them and they keep it down...

2) Gather evidence (recordings of the noise, neighbor testimony, etc) and get the police involved. Preferable when they have a party or function it's sure to be noisy and will bolster your case (diabolical muahahahaha) Nothing like having the cops bust up a function 

Pacifist Approach

3) They ignore your complains and you soundproof your ceiling... problem solved 

4) You move out and buy a landed house... 

wow, im surprise to read this even you have a 250mm thick fire wall seperate apart.

all your units come with pump? or else, u go outside , turn lower the water meter stopcock

i see, try my method, turn their water meter stop cock

sometime i also behtahan mine. something wrong with my one way valve to central water heater, always emit weird sound when open tap

but water pressure to high also can caused vibration. changing tap because there are sediment trap in faucet. yeah, better check with him. neighbour can be very nasty 

not sure, like my brother, my brother to a by pass the water tank directly to all bath room for better pressure.

mostly landed will do by pass like this since many installing own central main filter

it is stupid for syabas only allow direct main to kitchen tap and garden tap only.

Ya, my landed neighbor install a noisy water pump on the roof... Early morning already pumping