Selecting a Filter for Low Volume Irrigation Systems
by Stuart Spaulding,
CLIA Certified Landscape Irrigation Auditor Training & Communications Manager at DIG Corp.
Selecting the correct size and type of filter for a low-volume system is a critical decision that should be made with forethought and begins by acquiring some knowledge of the quality of the water that is being supplied. It’s essential to know what the primary contaminants are in the water supply so the correct type of filter can be selected.
There are 2 main types of Y filters available for use with landscape drip irrigation systems. It is an important component of the head assembly, and its function is to prevent emitters, drip line and micro sprinklers from clogging by keeping the water supply clean and relatively free of organic and inorganic contaminants.
The most common type are screen filters, which force the water through a cylindrical screen element. The foreign matter collects on the inside of the removable screen element. The screen material can be polyester or stainless steel (preferable), and is available in many different mesh sizes. These filters are primarily designed to remove inorganic contaminants and hard particulates such as sand. Organic, non-solid contaminants can clog these screens quickly, and they can be quite difficult to remove from the screen material. These filters are usually readily available in sizes from ¾”-2”. Models with a manual flush valve allow for quick flushing of the screen element with removing it from the filter body. Most drip systems require a filter of 120 mesh minimum.
A better choice if the water supply contains organic contaminants like algae or non-solid materials is the disk filter. Disk filters force the water through a set of stacked round disks, and the foreign matter collects on the outside of the disks. They have a larger surface area of filtration than screen filters and also do a good job removing inorganic contaminants. These filters can be cleaned manually by removing the disk set from the filter body, or by back-flushing it through the flush port.
All drip systems filters should be checked periodically and cleaned if necessary. It’s important to remember that landscape drip irrigation filters do not remove dissolved compounds, salts, and/or minerals commonly present in “hard” water.