What is hydram?

The hydraulic ram pump is an automatic device which works on the principle of water hammer. Hydraulic ram pump uses the kinetic energy of falling water to lift the small fraction of supply flow to a much greater height than the source, i.e. it uses a larger flow of water falling through small head to lift small flow of water to the much higher location. Generally, the sizes of the pumps are in the range of 1” to 6” and can pump between 1,500 to 72,000 litres of water a day, lifting it up to 200 meters vertically . It does not need any energy input other than water falling from higher point to lower point. It requires a reasonable flow of water falling from at least 1m head.

Where is it appropriate?

Hydram is particularly useful for mountain communities as it saves people long, daily journeys to water sources over dangerous mountain paths. It requires a high volume water source to work, as it can only lift a fraction of the water that powers it.

Why is hydram innovative?

  • Once a pump has been set up it is virtually cost free to operate, as its power comes from the water it provides.
  • People have easier access to more water for very little cost, allowing them to irrigate land and grow and sell more crops.
  • We can build parts of the systems by recycling everyday objects. We make old car tyres into valves, and use door hinges to move those valves.
  • Provided community members know how to maintain and operate hydram pumps, and we always ensure that they do, there’s really no downside!

Where have we used them?

We have installed hydram pumps in Dhading, Syangja and Achham districts in Nepal. These have improved the household annual income through the mobilization of water for increased production; increased the educational attendance and performance of children, especially girls through the reduction of time for water collection for girls; improved the health outcomes, especially women and children through the provision of more nutritious food produced in their home garden.

Dhading Hydram pumps

“We do not have to worry any more about falling down and breaking hands and legs on the path to the spring during the monsoon.” – Mrs Sita Dawadi, Treasurer of the Water Users Committee at Sunaula Bazaar.

Remote, marginalised villages in Nepal’s Dhading district are now being supplied with water using hydram pumps. Hydram is a technology ideally suited for supplying water to remote mountain villages. It uses the energy of falling water to pump it up high above its source, and has no operating costs.

The increased access to water improves hygiene and makes increased crop yields possible, and it frees the community from the burden of travelling huge distances for their water.

Tomatoes grown in Dhading thanks to Hydram and drip irrigation systems

Tomatoes grown in Dhading thanks to Hydram and drip irrigation systems

How does it work?

A hydram pump works by using the momentum of falling water to pump a small quantity of that water high above its source.

  • The pump is placed below a water source (such as a hillside pond) and connected to it with a pipe, called a drive pipe. Gravity feeds the water down the drive pipe to a chamber in the pump.
  • Two valves provide possible exits to the chamber. These are the waste valve and the delivery valve. The waste valve is set up so that it will normally be open, but high pressure in the chamber will force it shut. The delivery valve is set up so that it will normally be closed, but high pressure in the chamber will force it open.
  • Water flows into the chamber and flows out freely though the waste valve. This free flow allows the water to build up speed.
  • As more and more water flows faster and faster through the chamber, it exerts more and more pressure on the waste valve until the waste valve slams shut.
  • The water now has no exit from the chamber, but more water is still entering it at high speed. The pressure increases rapidly.
  • The increased pressure forces the delivery valve to open. The water flows through the delivery valve into a chamber full of compressed air, which sits at the bottom of a second pipe, called the delivery pipe.
  • The compressed air exerts pressure on the water, forcing it up the delivery pipe, which carries the water up to its destination.
  • With the water forced out of the pump, the pressure drops. The delivery valve closes, and the waste valve reopens.
  • The cycle repeats.


Practical Action, 2014 Hydraulic Ram Pumps [online] Avaliable here [Accessed 7th November 2014]

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