I have developed a water activated timing device that can discharge water at intermittent intervals without using any electricity. Your water pressure is all you need to power the system. Water pressure builds up in the water valve and is intermittently released by permanent magnets. Frequency rates are fully adjustable by the flow rate it is opened at.
It can be used for normal irrigation and also for hydroponics. It uses less water than conventional watering methods because the water discharge rates can be timed to match the natural assimilation rate the plants can take up the water.
It is fully automatic and can grow plants in any medium, including sand, and at great savings of water. The website is at www.spritzwiz.com