Day time it's 1.2 bar (as shown in outdoor water filter that's newly installed so it's not clogging issue), on some lucky days it's 1.4 bar. But at night, after 11pm, somehow it drops to 0.2 bar or lower and this has been going on for years.

Complained to air selangor, they closed aduan without doing anything.
Complained again, followed with general question to ask how they can close my aduan.
Guess what? They closed the complain on the same day without doing anything, then answered the general question by "you can make aduan".

Brain fried..

Anyone has idea how to solve this?

p/s: i'm based in shah alam. Double storey, old house >20 yrs.

Update:
Complained like 5 times to Air Selangor.
On 4th time, they detected leaking pipe problem.. so they dug a hole at my front car porch, broke those nice tiles then tampal balik with cement.
And guess what?? NO CHANGE at all to water pressure!
On 5th complaint they said they checked and nothing is wrong. They can't do anything.

So yeah.. all problems remain here. Just gotta buy a pump.