Many houses in Bangkok have these huge tanks for water. At first, I presumed they were in case there was a shortage or problem witrh the mains, but that is highly unlikely in the capital. The other day I realised that maybe they're to ensure good pressure when pumped into the house.

What's the truth, please?

Both of the above. Some districts in Bangkok have very poor water pressure due too many people for so little water. The majority of the time our townhouse only gets sufficient water during the wee hours of the night. Also it is a bad idea to pump water out of the government supply as you may end up sucking up water from unclean sources. Called flow-back or something like that where external water can be sucked back up through a hose and into the system if there is negative pressure on the system.

Both of the above. Some districts in Bangkok have very poor water pressure due too many people for so little water. The majority of the time our townhouse only gets sufficient water during the wee hours of the night. Also it is a bad idea to pump water out of the government supply as you may end up sucking up water from unclean sources. Called flow-back or something like that where external water can be sucked back up through a hose and into the system if there is negative pressure on the system.

yepp, both, and all over the country

the pressure from supply is often low, and certanly does not reach 3rd floor or higher. Flow is also low even when pressure is adequate, as most supply pipes and meters are 1/2 inch.

Tank and domestic pump solves it

Thanks, that seems to make sense.

is there a recommended minimum pump strength for a regular two-storey town house with a tank? It's just that we have a 150, will soon be moving and if I need stronger I may as well get it from the start. I appreciate that the stronger the betteer, but...

Thanks, that seems to make sense.

is there a recommended minimum pump strength for a regular two-storey town house with a tank? It's just that we have a 150, will soon be moving and if I need stronger I may as well get it from the start. I appreciate that the stronger the betteer, but...

Mitsu 150 installed at groundfloor is to small for 2 nd level, at least if you have an instant hotwaterheater shower 2nd level. I would choose a 305Q. 150 on the roof could work

None of the well pumps will give more than about 30psi so if you want good flow through point of use shower you might want to get one of the 60psi type pumps (such as Grundfos). But be aware it can test your water pipe connections as often Thai do not cement joints well. Best used with external pipes.

I have a Hitachi 200 which replaced a 250 unit that after 10 years needed replacement. The unit is more than strong enough for a 2 story application. My pump services both my house and my guest house with no flow or pressure problems.

Edit - be very careful with high pressures. As one of the posts above indicates it can cause havoc with your plumbing if to strong. And you bum gun can become a lethal weapon.

None of the well pumps will give more than about 30psi so if you want good flow through point of use shower you might want to get one of the 60psi type pumps (such as Grundfos). But be aware it can test your water pipe connections as often Thai do not cement joints well. Best used with external pipes.

Grundfos also has excellent pumps at max 2,8 bar, with flow 3 times the flow of Mitsu 305. at double the price

I have a Hitachi 200 which replaced a 250 unit that after 10 years needed replacement. The unit is more than strong enough for a 2 story application. My pump services both my house and my guest house with no flow or pressure problems.

until the groundfloor washingmachine, dishwasher and kitchensink is used at the same time. No upstairs water pressure left with a 200. Barely with a 300.

I have a Hitachi 200 which replaced a 250 unit that after 10 years needed replacement. The unit is more than strong enough for a 2 story application. My pump services both my house and my guest house with no flow or pressure problems.

Edit - be very careful with high pressures. As one of the posts above indicates it can cause havoc with your plumbing if to strong. And you bum gun can become a lethal weapon.

I know exactly what you mean

And you bum gun can become a lethal weapon.

Not if you put an adjustable tap on it as most places do. Then set it for the flow you want. They only cost about 30 baht.

I have a Hitachi 200 which replaced a 250 unit that after 10 years needed replacement. The unit is more than strong enough for a 2 story application. My pump services both my house and my guest house with no flow or pressure problems.

until the groundfloor washingmachine, dishwasher and kitchensink is used at the same time. No upstairs water pressure left with a 200. Barely with a 300.

Sounds like a capacity problem and not a pressure problem.

I have a Hitachi 200 which replaced a 250 unit that after 10 years needed replacement. The unit is more than strong enough for a 2 story application. My pump services both my house and my guest house with no flow or pressure problems.

until the groundfloor washingmachine, dishwasher and kitchensink is used at the same time. No upstairs water pressure left with a 200. Barely with a 300.

Sounds like a capacity problem and not a pressure problem.

without measuring I would guess both, and still no water in upstairs hot water shower

Different pumps have different flow capacities, as the overall rate of flow is directly related to the pump capacity. If your household has a 10-gallon per minute demand, there will be trickling water if the pump will only supply five gallons per minute.

A simple test would be to turn off all water points and test the pressure of the upstairs unit. If it still is not sufficient than there is still the possibility of an inline obstruction in your piping.

Sorry, just don't see how a 200 unit does not have enough pressure to service a second story.

Different pumps have different flow capacities, as the overall rate of flow is directly related to the pump capacity. If your household has a 10-gallon per minute demand, there will be trickling water if the pump will only supply five gallons per minute.

A simple test would be to turn off all water points and test the pressure of the upstairs unit. If it still is not sufficient than there is still the possibility of an inline obstruction in your piping.

Sorry, just don't see how a 200 unit does not have enough pressure to service a second story.

inline obstruction indeed, inside every on demand hotwater heater. Cold water no problem

I own a number of buildings, and 305Q on groundlevel is barely sufficient for 2 or 3 storey if you have hotwater on demand. Even a 2 storey (with hotwatertank and 8 bathrooms), 305Q replaced with high flow Grundfos. So in this building not really a pressure problem as Grundfos is also set at 2,8 bar, but a flow problem when many taps used same time.

Why dont they just put a water tank in the roof and let gravity do it like in the UK and Ireland ?