Automatic water lifting pump?

[perrybond]

I have a 500 litre water tank in the cellar, filled with rain water. It is on a plinth so I can mount an external pump 400mm below it's invert level
The pump would then have to lift the water about 2m to fill a toilet cistern.
It does not need to fill fast, so a high flow rate is not required, but it does need to be automatic.

Does anybody know a suitable pump?

Lift pumps I've looked at seem to work on a manual switch (or float valve for sumps)

Power shower pumps are automatic, but rely on a positive head pressure to work.

Thanks for any suggestions

 

[TicklyT]

There are negative head pumps available, which may meet your needs.

How about replacing the cistern float valve with a float operated switch to control a pump?

Or, to stop the pump running every flush, which may become annoying at night, put a water tank in the loft, filled by pumping the water from your basement and controlled by a float operated switch and a time clock?

 

[perrybond]

Thanks
"negative head pump" -It's much easier to find things on the internet when you have the right key words; I will try this.

If I can't find a pump. Your second suggestion is a cool alternative.

I have no loft, but as it is a shop, noise will not be a problem