Has anyone got a formula to work out what size water pump I need for my system? I have a 100 sq m house with two bathrooms and one kitchen. I have to supply two showers,two wash basins,two toilets in the bathrooms and cold and hot taps in the kitchen. This is a single storey house and the maximum distance from pump to tap would be 10 metres. There are many different pumps and I want to make sure the pump is big enough with a bit to spare.

Thanks in advance. Keith

The posting of the Mitsubishi water pump chart  to consider from Vocal Neal is a very good guideline. The OP might also have a better water pump installation experience in Thailand if he goes to a water pump shop where staff know the product and the owner will take a personal interest in the expat customer. I believe every province in Thailand has at least one better staffed and better stocked Mitsubishi water pump dealer. 

I have basically the same size house and setup as you. we live in a village with terrible water pressure and the water seemed to shut off daily for hours.

 

I bought the MITSUBISHI EP-255 Q5 250W CONSTANT PUMP at HomePro in Korat. I also installed a 700 liter water tank. The pump has been EXCELLENT. I wish I had bought a larger water tank.because the water from the village is so unreliable our tank ran dry one time.

 

HomePro gave me a diagram and all the parts I needed. My son-in-law and I installed the whole system in one afternoon and it has been the best investment I have made since being in Korat. We now have remodeled the bathroom and installed a rain shower and there will be no going back.

On 30/09/2017 at 11:38 AM, VocalNeal said:

 

That is an excellent chart but now a little dated it is missing the newer Mitsubishi  inverter and the multi stage series CMCH (constant pressure) UMCH (with pressure tank) MCH 

The chart under has the inverter but not the multi stage pumps 

 

 

Inverters are only a benefit if it is a constant state, which I do not believe is the case if flushing a toilet or having a 3 minute shower. The inverter circuit also uses power. 

 

Most of the so called "new" pumps listed would seem from a wattage point of view to be overkill? They would be OK for a very large house or a small apartment building. 

A person probably should go with approx a 250 watt pump for a two story home (or one story home) when wanting significantly more pressure and volume capability....the 250 watt point seems to be the point where most pumps take a very significant increase in pressure/volume capability compare to pumps rated below 250 watts..    See below post/thread for more info.