Tomato plants in a modern glass greenhouse are irrigated by a drip irrigation system. This system is composed of several parts:

• Fresh water tanks;
• Irrigation unit with fertilizer tanks and a mixing tank;
• High pressure main pipelines from the irrigation unit to the growing area;
• Irrigation valve sets;
• Semi lines;
• Drip hoses;
• Drippers;

Fresh water tanks are usually made out of corrugated steel sheets, with special liners within the tank which makes the tank water tight and also protect the tank from damage from rocks and any type of contact damage. They are usually filled with well water and with rain water. There is an overflow system, so in case of heavy rain or any type of problem with the filling of the tank, the excess water will go through this system and outside the greenhouse. We usually use 120 m3 (31700 gal) tanks for 1ha (2.5 acres)  greenhouse for a daily supply. But sometimes water tanks with a volume of 2 or 3 day supply are delivered. Just to be on a safe side in case of any kind of water supply shortage.

The main danger to the fresh water tank is acid. Nitric acid is usually used in greenhouses for cleaning UV lamps and other purposes. If this acid comes into contact with a fresh water tank, it can cut the steel tank sheets like a razor knife. The damage from 340 or more tones of water suddenly bursting out of the tank and flooding the working/technical area is huge. So it is advisable to take all and any measures available to separate nitric acid and the tanks, so they never come in contact by any means.

Irrigation units are the heart of the irrigation system. There are several types, and here is covered a “mixing tank” type which has proven to be very reliable and easy to maintain. This type of irrigation unit has a fertilizer tank for A fertilizers, another fertilizer tank for B fertilizer, and a special smaller tank for a Lye or Acid solution. This one is used for setting the freshwater ph. All these fertilizers are mixed in the mixing tank and then the fertilizer solution is pumped to the growing area. Irrigation units of 60 m3/h (15850 gal/h) is big enough for a standard 2ha (5 acres) tomato greenhouse.

In the growing area the fertilizer solution is transported to the valve sets which open and close the flow towards the irrigation  semi lines and drip hoses.

Drip hoses are located along the growing gutters and drippers themselves are delivering the irrigation mixture to the plants.