A gravity irrigation system is a cheap and efficient way to supply water to a smaller crop area. This would be particularly cost-effective if the climate of the area can provide sufficient rainfall to keep the reservoir refilled using rainwater harvesting methods. The basic irrigation system is very simple, consisting of a raised tank with a pipe at the bottom that feeds water to the main drip irrigation system , which is controlled either by hand or by a very efficient battery-powered timer that regulates the rate at which crops are watered.
The following components are required
Photo from https://www.israel21c.org/new-gravity-watering-system-saves-resources-and-raises-yields/
It must hold at least one day's worth of water, the larger the tank's capacity, the more often it needs to be filled. The difficulty with a very large tank is that it needs to be raised above the crops, and filling a very high tank is more work, the tank needs to be raised because it increases the pressure, which must be constant at the drip line feed point to distribute the water evenly.
A structure that holds a water tank
Can be made of anything that can support the weight of the tank when filled with water and must be able to withstand external forces, for example an 880 gal tank full of wind weighs 4 tons.
At the base of the tank, there should be a pipe through which the water flows out, and if the tank capacity is more than one day's water, it is useful to have a shut-off valve at this connection point. If the timer method is used, the pipeline supplies water through the filter. In order to increase the pressure, different sizes of pipelines should be used This is done by gradually reducing the size of the pipelines used.
Timer and filter
There are many models of battery-operated timers that can be set up and used throughout the season. These timers regulate the frequency of water discharge into the drippers. A filter must be installed in the water line before the timer valves, this prevents the smaller lines from clogging
Valves and drip lines
Shut-off valves should be installed between the tank pipes and watering pipes and before the timer valves Drip lines are medium lines and sprinklers that can be purchased at any garden supply store