Usually, I turn it off when not in use.

As long as I had been living in my old DSH before I sold it.years later.

Thks for this. Pumps can be smaller capacity if judiciously connected to needed outlets that require the desired flow rate.

This can also be achieved during renovation, where the plumbing for WC inlet refill are separated in each bathroom from cold supply to each bathroom. A separate dedicated distribution pipe of sufficient diameter and slope and an appropriate reducing (e.g. 1" or 3/4" to 0.5") outlet to each WC should offset the pressure loss and yet achieve satisfactory refill time though not as fast as the pumped assisted rate. This also avoid water hammer issues or leaking toilet refill valves overwhelmed by persistent and eventual wear from pump pressure. The inlet point at the wall will of course terminate at a higher distance from the toilet floor eg 12-24" vs the usual 6-12" which is shared with the cold plumbing line to basin or bath/ shower depending on bath layout. It also avoid the nightmarish scenario of a leaky flush valve that will empty the tangki in minutes and causing the pump to run dry but some models will have dry run protection.

Combine this with low flow rate but high pressure wash basin aerators and shower head e.g. Takagi Kimochii or the 200 holes Korean fine spray type, the required overall flow rate can be reduced somewhat thus allowing a smaller pump with that flow rate to be used.

This post has been edited by halcyon27: Jul 18 2020, 07:07 PM

I for one would isolate the ground floor pipe circuit from the pump meaning upper floor bathroom are pump driven only. The lower floor should be able to live without it unless:
1. Centralised hot water storage tank for all 3 bathrooms
2. old pipes with blockages restricting normal flow downstairs.
The pressure issue is clearly with upper floor. I had bad experience with occasional leaky toilet flush valves that empty my tangki. Problem lessened but still occur if I had continue living in my old DSH unless using high quality flush valves on downstairs toilet. Human habit in not switching off main switch on the water pump at times coupled with leaky flush valves can harm the pump.

You might want to check this post out. The poster should be able to elaborate. Put into context from his technique, if bypassing, it's only meant for ground floor pipes to kitchen and laundry only.
Summary, isolate with two outlets from tangki:
1. Pump driven for upper floor only unless exception mentioned.
2. Lower floor kitchen and laundry can consider bypass like shown in linked post plus its design input further discussed here.

This post has been edited by halcyon27: Dec 15 2020, 07:00 PM