How it Works

What is a Self-Cleaning Strainer?

A self-cleaning strainer (or self-cleaning filter) is a type of water filter which utilizes system pressure to clean itself. Forsta self-cleaning strainers will remove unwanted particles from a water source in the 5-4,000 micron range and at flow rates ranging from 10gpm up to many thousands of gpm in large applications. Self-cleaning strainers save users money on water, energy, maintenance and equipment replacement. They are often referred to as automatic self-cleaning strainers because unlike many systems, the technology requires no routine maintenance. For example, an automatic self-cleaning strainer, will not require constant change outs and system shutdowns like a bag or cartridge filter. Click here to compare self-cleaning strainers to other filter technologies including sand filters and separators. In a self-cleaning strainer, basic bi-annual or annual inspection (depending on particle load) replaces the need for daily, weekly or monthly shutdowns.

Forsta self-cleaning strainers are used to protect pipes and a wide range of downstream equipment. Without adequate filtration, pipes acquire scale buildup causing an increase in the energy required to pump system water.

Clogged pipes need strainer

Even city water without adequate filtration will cause buildup and eventually clog pipes.


As pipe orifices become smaller, more energy is required to pump the same volume of water. Effects of pumping dirty water through a piping system include excessive scale buildup, contaminant settling, and clogged/fouled equipment which all contribute to poor pump performance. Implementing a Forsta self-cleaning water strainer prevents these consequences and saves energy.

The Nuts and Bolts of a Self-Cleaning Strainer

How it works schematic


In a self-cleaning strainer, a rigid cylinder screen strains particles from a water source, trapping debris on the inside. This layer of buildup causes differential pressure across the inlet and outlet. A controller monitors the filter and opens a flush valve when it senses adequate differential pressure. This creates rapid flow through the internal cleaning apparatus, which vacuums buildup from the screen and expels it.

Automatic Backwash Does Not Interrupt System Flow

A unique characteristic of self-cleaning strainers is that the backwash cycle does not require the entire system flow to stop and reverse, as is the case for many other types of filters. Instead, a point-of-suction backwash reverses flow across the screen only directly in front of suction nozzles. This allows the cleaning mechanism to scan and clean the screen incrementally without disrupting the main flow through the filter.

Basic Startup and Shutdown Procedures

Review basic startup and shutdown procedures for your 180 Series self-cleaning water filter in this <2 minute video.

Once Your Self-Cleaning Filter is Installed

There are a few checkpoints that ensure success in self-cleaning filter operation. The video below provides a detailed explanation of how to check these critical parameters.

Performance Checklist in Action

Watch an installation review addressing the performance checklist on a D8-LP180 model filter.

Automatic self cleaning strainers are used in a variety of applications where continuous water flow is crucial, including equipment protection in industrial water filtration, nozzle protection in irrigation filtration systems, membrane protection in municipal water filtration systems and much more.

We encourage you to collaborate with Forsta engineers to save your company valuable time, money and resources. We’ll make sure you get the best self-cleaning strainers for your industrial, irrigation and municipal water filtration applications. Call us today at 310-837-7177 or fill out our quote form and we’ll respond right away to help you find the best filter for the job.