This is an easy, cheap, non-moving parts, DIY water pump.
Since it has no moving parts, it can hardly break down.
It is based on the air-lift effect.
It is a very old system, I just found a cheap and easy way to build it with a T junction.
No glue, no welding required.
I use it in hydroponic projects and water fountains.
Can also be used for irrigation, with a bicycle pump fitted with a non return valve.
All parts I use are aquarium parts, and can be found in aquarium or pet shops.
You can also use a compressor for a higher flow.

List of parts;
a 10mm T junction
an aquarium air pump (the stronger PSi you can buy, the better)
an air tube for the aquarium pump 4mm
a 10 mm tube

When i say 10mm T junction , it is the inner measurement of the tube.
A regular T from Hazelock 1/2" can be used, as Hazelock gives the outside measurements.
I use the inner measures, because i fit my tube inside the T junction.
See later why.

Step 1: Slip the Air Hose Into the T

Slip the 4mm air hose into the10mm T junction.
To do that, the easy way is to start inserting the air hose into the shorter end of the T.
Then use a pencil (but the blunt side) to help push it trough.
This is the toughest part of the project.
Then pull the air hose all the way, till you leave about 1 inch or 30mm sticking out of the
short side of the T.

Step 2: Diameter of the Water Hose

The diameter of the water hose is critical.
The system works by injecting air into the T.
Air bubbles will push the water upside, so do not use a too wide tube, otherwise it will not work.

Troubleshooting; these are possible causes;
T must be immersed in minimum 5 inches of water.
Airflow is not strong enough, not enough pressure.
Diameter of the hose is too big.

Step 3: Attach the Air Pump

No picture, i guess you know how to attach the air pump.

Step 4: Blurping Water Out

On my hydroponic projects, i attach a timer to the air pump.
This is an amarillys in a colander and a bucket, but this is another instructable.
The pump will only work if there is enough water in the bucket.
This system has a slow but constant flow.
The only disadvantage of this system is a slight blurping noise.