Water pressure and pipe friction calculation - help!

Hi

I'm setting up a eco-friendly, comunity-based lodge in a remote part
of South Africa (see www.bulungula.com). I'm trying out various
designs for a solar water heater and have found the simplest to be
leaving 160m of 40mm black plastic irrigation pipe in the sun for a
few hours and then to turn on the tap which fills the pipe with cold
water and pushes the hot water out the end into an insulated water
container. This works fine in the city where I have municipal water
and thus good water pressure. However, the lodge will be situated in
an area where there is no running water, so I'll be using a solar pump
to pump water to 10 000 litre tanks (about 2 500 gallons). The tank is
3m high and will be standing on ground level.

Does anyone know how to calculate whether the pressure of these 10
tons of water will be sufficient to overcome the friction in 160m of
pipe and result in water flowing out the end at a rate of at least 2
liters per minute?

I realise the pipe specifications are crucial, the info I have is:
diameter: 40mm (1 3/4 inch)
length: 160m  (170 yards)
pipe material: polythene I think ("normal" grade 3 (3mm) black
irrigation pipe)

As mentioned above, the water tank is 3m tall with a tap about 30 cm
from the base.

Any help with this would be much appreciated - I'm not in a position
to test this beforehand, and it will be quite difficult to resolve
this once I'm out in the bush.

Thanks
Dave