Water Pump

[SteveD]

In her garden, my daughter has one of those 1000 litre plastic water reservoirs in a tubular metal frame which catches rainwater.  She wants to find a pump with enough oomph to attach to it or immerse in it to which she could fit a 20 metre hose in order to water the garden.

Any ideas what she should search for online (any links?). What specifications should she look for (flow rate, pressure etc)?

 

Thanks in advance for any help.