QUOTE(ozak @ May 19 2021, 09:06 AM)
If the pic is correct, and both tank at the same ground level, why need a pump ?
The solution is as simple as this.

Both tank will fill up at the same time. The pump is only pump water into the house. Don't need gadget or whatsoever thing to monitor.
The only way you can do for the low pressure is to complain to the Syabas if from Selangor. "the water for mains has to
travel like 3 m and climb 1.2m to the first tank." The water already travel more than 3m before reach your house.
QUOTE(mini orchard @ May 19 2021, 09:21 AM)
I think you misread his post.
1st tank is near the main with pump to 2nd tank.
2nd tank is on roof ...supply to kitchen and bathroom.
Usage faster than refill from main, hence need a controller to stop pump when water level is low. Certain hours of the day, there is no supply from main to refill tank 1.
Water pressure is poor at my area. The 1st pic is now the solution. Put a new tank lower than 2 feet (meter main water), let water flow into it. Then pump to existing tank (about 3m away). I don't want to pull water with a pump directly from the meter because it will result in expensive water bill. Like from RM20 to 80 (and that is only pulling 2 weeks at night for about 2 hours). I know people who pull constantly that get RM300+ in water bills. In severe cases when there is a water cut/ high community usuage of water, then water will not flow out at all. If not covid-19 time, usually if school holiday/any holiday in general, lots of people will come here and water will be scarce.
Thanks all again for the reply. Thread close for now.