Maintenance of Drip Irrigation Systems The most common problem seen in drip irrigation applications is congestion of drippers. Drippers are usually congested because of furring or thin particles that pass through the filter system. Congestions due to furring can usually be postponed or prevented using chemical (phosphoric acid and nitric acid) substances, but congestions due to foreign materials in the filter system cannot be solved usually and changing the drip irrigation pipes with a higher cost can be possible. For this reason, it is important to use a quality filter system in the beginning which is able to back flush itself. It is necessary to wash the drip irrigation pipes twice a year using chemicals to prevent furring based congestions.